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STM32L051x6, x8 Datasheet

STMicroelectronics

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Datasheet

This is information on a product in full production.
May 2018 DS10184 Rev 9 1/132
STM32L051x6 STM32L051x8
Access line ultra-low-power 32-bit MCU Arm
®
-based Cortex
®
-M0+,
up to 64 KB Flash, 8 KB SRAM, 2 KB EEPROM, ADC
Datasheet - production data
Features
Ultra-low-power platform
1.65 V to 3.6 V power supply
-
40 to 125 °C temperature range
0.27 µA Standby mode (2 wakeup pins)
0.4 µA Stop mode (16 wakeup lines)
0.8 µA Stop mode + RTC + 8 KB RAM retention
88 µA/MHz in Run mode
3.5 µs wakeup time (from RAM)
5 µs wakeup time (from Flash memory)
Core: Arm
®
32-bit Cortex
®
-M0+ with MPU
From 32 kHz up to 32 MHz max.
0.95 DMIPS/MHz
Memories
Up to
64 KB Flash memory with ECC
–8KB RAM
2 KB of data EEPROM with ECC
20-byte backup register
Sector protection against R/W operation
Up to 51 fast I/Os (45 I/Os 5V tolerant)
Reset and supply management
Ultra-safe, low-power BOR (brownout reset)
with 5 selectable thresholds
Ultra-low-power POR/PDR
Programmable voltage detector (PVD)
Clock sources
1 to 25 MHz crystal oscillator
32 kHz oscillator for RTC with calibration
High speed internal 16 MHz factory-trimmed RC
(+/- 1%)
Internal low-power 37 kHz RC
Internal multispeed low-power 65 kHz to
4.2 MHz RC
PLL for CPU clock
Pre-programmed bootloader
USART, SPI supported
Development support
Serial wire debug supported
Rich Analog peripherals
12-bit ADC 1.14 Msps up to 16 channels (down
to 1.65 V)
2x ultra-low-power comparators (window mode
and wake up capability, down to 1.65 V)
7-channel DMA controller, supporting ADC, SPI,
I2C, USART, Timers
7x peripheral communication interfaces
2x USART (ISO 7816, IrDA), 1x UART (low
power)
Up to 4x SPI 16 Mbits/s
2x I2C (SMBus/PMBus)
9x timers: 1x 16-bit with up to 4 channels, 2x 16-bit
with up to 2 channels, 1x 16-bit ultra-low-power
timer, 1x SysTick, 1x RTC, 1x 16-bit basic, and 2x
watchdogs (independent/window)
CRC calculation unit, 96-bit unique ID
All packages are ECOPACK
®
2
Table 1. Device summary
Reference Part number
STM32L051x6
STM32L051C6,
STM32L051K6,
STM32L051R6,
STM32L051T6
STM32L051x8
STM32L051C8,
STM32L051K8,
STM32L051R8,
STM32L051T8
UFQFPN32
5x5 mm
LQFP32 7x7 mm
LQFP48 7x7 mm
LQFP64 10x10 mm
Standard and thin
WLCSP36
2.61x2.88 mm
TFBGA64
5x5 mm
FBGA
www.st.com
Contents STM32L051x6 STM32L051x8
2/132 DS10184 Rev 9
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1 Device overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
2.2 Ultra-low-power device continuum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3 Functional overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 Low-power modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 Interconnect matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.3 Arm® Cortex®-M0+ core with MPU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4 Reset and supply management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.4.1 Power supply schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.4.2 Power supply supervisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.4.3 Voltage regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.5 Clock management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.6 Low-power real-time clock and backup registers . . . . . . . . . . . . . . . . . . . 24
3.7 General-purpose inputs/outputs (GPIOs) . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.8 Memories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.9 Boot modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.10 Direct memory access (DMA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.11 Analog-to-digital converter (ADC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.12 Temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.12.1 Internal voltage reference (VREFINT) . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.13 Ultra-low-power comparators and reference voltage . . . . . . . . . . . . . . . . 27
3.14 System configuration controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.15 Timers and watchdogs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.15.1 General-purpose timers (TIM2, TIM21 and TIM22) . . . . . . . . . . . . . . . . 28
3.15.2 Low-power Timer (LPTIM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.15.3 Basic timer (TIM6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.15.4 SysTick timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.15.5 Independent watchdog (IWDG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.15.6 Window watchdog (WWDG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
DS10184 Rev 9 3/132
STM32L051x6 STM32L051x8 Contents
4
3.16 Communication interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.16.1 I2C bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.16.2 Universal synchronous/asynchronous receiver transmitter (USART) . . 31
3.16.3 Low-power universal asynchronous receiver transmitter (LPUART) . . . 31
3.16.4 Serial peripheral interface (SPI)/Inter-integrated sound (I2S) . . . . . . . . 32
3.17 Cyclic redundancy check (CRC) calculation unit . . . . . . . . . . . . . . . . . . . 32
3.18 Serial wire debug port (SW-DP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4 Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5 Memory mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.1 Parameter conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.1.1 Minimum and maximum values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.1.2 Typical values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.1.3 Typical curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.1.4 Loading capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.1.5 Pin input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.1.6 Power supply scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.1.7 Current consumption measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.2 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6.3 Operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
6.3.1 General operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
6.3.2 Embedded reset and power control block characteristics . . . . . . . . . . . 53
6.3.3 Embedded internal reference voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 54
6.3.4 Supply current characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.3.5 Wakeup time from low-power mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
6.3.6 External clock source characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6.3.7 Internal clock source characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.3.8 PLL characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
6.3.9 Memory characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
6.3.10 EMC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.3.11 Electrical sensitivity characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.3.12 I/O current injection characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.3.13 I/O port characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
6.3.14 NRST pin characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Contents STM32L051x6 STM32L051x8
4/132 DS10184 Rev 9
6.3.15 12-bit ADC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.3.16 Temperature sensor characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.3.17 Comparators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.3.18 Timer characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.3.19 Communications interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
7 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.1 LQFP64 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.2 TFBGA64 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.3 LQFP48 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.4 Standard WLCSP36 package information . . . . . . . . . . . . . . . . . . . . . . . .111
7.5 Thin WLCSP36 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . .114
7.6 LQFP32 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116
7.7 UFQFPN32 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119
7.8 Thermal characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
7.8.1 Reference document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
8 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
DS10184 Rev 9 5/132
STM32L051x6 STM32L051x8 List of tables
6
List of tables
Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. Ultra-low-power STM32L051x6/x8 device features and peripheral counts. . . . . . . . . . . . . 11
Table 3. Functionalities depending on the operating power supply range . . . . . . . . . . . . . . . . . . . . 15
Table 5. Functionalities depending on the working mode
(from Run/active down to standby) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 4. CPU frequency range depending on dynamic voltage scaling . . . . . . . . . . . . . . . . . . . . . . 16
Table 6. STM32L0xx peripherals interconnect matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 7. Temperature sensor calibration values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 8. Internal voltage reference measured values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 9. Timer feature comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 10. Comparison of I2C analog and digital filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 11. STM32L051x6/8 I2C implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 12. USART implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 13. SPI/I2S implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 14. Legend/abbreviations used in the pinout table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 15. STM32L051x6/8 pin definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 16. Alternate function port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Table 17. Alternate function port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Table 18. Alternate function port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 19. Alternate function port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 20. Voltage characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Table 21. Current characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 22. Thermal characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 23. General operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 24. Embedded reset and power control block characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 25. Embedded internal reference voltage calibration values . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 26. Embedded internal reference voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 27. Current consumption in Run mode, code with data processing running from Flash. . . . . . 56
Table 28. Current consumption in Run mode vs code type,
code with data processing running from Flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Table 29. Current consumption in Run mode, code with data processing running from RAM . . . . . . 58
Table 30. Current consumption in Run mode vs code type,
code with data processing running from RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 31. Current consumption in Sleep mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Table 32. Current consumption in Low-power run mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Table 33. Current consumption in Low-power sleep mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Table 34. Typical and maximum current consumptions in Stop mode . . . . . . . . . . . . . . . . . . . . . . . . 62
Table 35. Typical and maximum current consumptions in Standby mode . . . . . . . . . . . . . . . . . . . . . 63
Table 36. Average current consumption during Wakeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Table 37. Peripheral current consumption in Run or Sleep mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Table 38. Peripheral current consumption in Stop and Standby mode . . . . . . . . . . . . . . . . . . . . . . . 65
Table 39. Low-power mode wakeup timings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Table 40. High-speed external user clock characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Table 41. Low-speed external user clock characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Table 42. HSE oscillator characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Table 43. LSE oscillator characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table 44. 16 MHz HSI16 oscillator characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Table 45. LSI oscillator characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
List of tables STM32L051x6 STM32L051x8
6/132 DS10184 Rev 9
Table 46. MSI oscillator characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Table 47. PLL characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Table 48. RAM and hardware registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Table 49. Flash memory and data EEPROM characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Table 50. Flash memory and data EEPROM endurance and retention . . . . . . . . . . . . . . . . . . . . . . . 75
Table 51. EMS characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Table 52. EMI characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Table 53. ESD absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Table 54. Electrical sensitivities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Table 55. I/O current injection susceptibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Table 56. I/O static characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Table 57. Output voltage characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Table 58. I/O AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Table 59. NRST pin characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Table 60. ADC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Table 61. RAIN max for fADC = 16 MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Table 62. ADC accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Table 63. Temperature sensor calibration values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Table 64. Temperature sensor characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Table 65. Comparator 1 characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Table 66. Comparator 2 characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Table 67. TIMx characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Table 68. I2C analog filter characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Table 69. SPI characteristics in voltage Range 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Table 70. SPI characteristics in voltage Range 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Table 71. SPI characteristics in voltage Range 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Table 72. I2S characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Table 73. LQFP64 - 64-pin, 10 x 10 mm low-profile quad flat
package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Table 74. TFBGA64 – 64-ball, 5 x 5 mm, 0.5 mm pitch thin profile fine pitch ball grid array package
outline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Table 75. TFBGA64 recommended PCB design rules (0.5 mm pitch BGA). . . . . . . . . . . . . . . . . . . 106
Table 76. LQFP48 - 48-pin, 7 x 7 mm low-profile quad flat package mechanical data. . . . . . . . . . . 109
Table 77. Standard WLCSP36 - 2.61 x 2.88 mm, 0.4 mm pitch wafer level chip scale
mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Table 78. Standard WLCSP36 recommended PCB design rules. . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Table 79. Thin WLCSP36 - 2.61 x 2.88 mm, 0.4 mm pitch wafer level chip scale
package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Table 80. WLCSP36 recommended PCB design rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Table 81. LQFP32 - 32-pin, 7 x 7 mm low-profile quad flat package mechanical data. . . . . . . . . . . 117
Table 82. UFQFPN32 - 32-pin, 5x5 mm, 0.5 mm pitch ultra thin fine pitch quad flat
package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Table 83. Thermal characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Table 84. STM32L051x6/8 ordering information scheme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Table 85. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
DS10184 Rev 9 7/132
STM32L051x6 STM32L051x8 List of figures
8
List of figures
Figure 1. STM32L051x6/8 block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 2. Clock tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 3. STM32L051x6/8 LQFP64 pinout - 10 x 10 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 4. STM32L051x6/8 TFBGA64 ballout - 5x 5 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 5. STM32L051x6/8 LQFP48 pinout - 7 x 7 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 6. STM32L051x6/8 WLCSP36 ballout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 7. STM32L051x6/8 LQFP32 pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 8. STM32L051x6/8 UFQFPN32 pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 9. Pin loading conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 10. Pin input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 11. Power supply scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Figure 12. Current consumption measurement scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Figure 13. IDD vs VDD, at TA= 25/55/85/105 °C, Run mode, code running from
Flash memory, Range 2, HSE, 1WS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Figure 14. IDD vs VDD, at TA= 25/55/85/105 °C, Run mode, code running from
Flash memory, Range 2, HSI16, 1WS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Figure 15. IDD vs VDD, at TA= 25/55/ 85/105/125 °C, Low-power run mode, code running
from RAM, Range 3, MSI (Range 0) at 64 KHz, 0 WS . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 16. IDD vs VDD, at TA= 25/55/ 85/105/125 °C, Stop mode with RTC enabled
and running on LSE Low drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Figure 17. IDD vs VDD, at TA= 25/55/85/105/125 °C, Stop mode with RTC disabled,
all clocks OFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Figure 18. High-speed external clock source AC timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Figure 19. Low-speed external clock source AC timing diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Figure 20. HSE oscillator circuit diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Figure 21. Typical application with a 32.768 kHz crystal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Figure 22. HSI16 minimum and maximum value versus temperature . . . . . . . . . . . . . . . . . . . . . . . . . 71
Figure 23. VIH/VIL versus VDD (CMOS I/Os) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Figure 24. VIH/VIL versus VDD (TTL I/Os) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Figure 25. I/O AC characteristics definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Figure 26. Recommended NRST pin protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Figure 27. ADC accuracy characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Figure 28. Typical connection diagram using the ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Figure 29. Power supply and reference decoupling (VREF+ not connected to VDDA) . . . . . . . . . . . . . 89
Figure 30. Power supply and reference decoupling (VREF+ connected to VDDA). . . . . . . . . . . . . . . . . 90
Figure 31. SPI timing diagram - slave mode and CPHA = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Figure 32. SPI timing diagram - slave mode and CPHA = 1(1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Figure 33. SPI timing diagram - master mode(1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Figure 34. I2S slave timing diagram (Philips protocol)(1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Figure 35. I2S master timing diagram (Philips protocol)(1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Figure 36. LQFP64 - 64-pin, 10 x 10 mm low-profile quad flat package outline . . . . . . . . . . . . . . . . 101
Figure 37. LQFP64 - 64-pin, 10 x 10 mm low-profile quad flat recommended footprint . . . . . . . . . . 103
Figure 38. LQFP64 marking example (package top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Figure 39. TFBGA64 – 64-ball, 5 x 5 mm, 0.5 mm pitch thin profile fine pitch ball
grid array package outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Figure 40. TFBGA64 – 64-ball, 5 x 5 mm, 0.5 mm pitch, thin profile fine pitch ball
,grid array recommended footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Figure 41. TFBGA64 marking example (package top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
List of figures STM32L051x6 STM32L051x8
8/132 DS10184 Rev 9
Figure 42. LQFP48 - 48-pin, 7 x 7 mm low-profile quad flat package outline . . . . . . . . . . . . . . . . . . 108
Figure 43. LQFP48 - 48-pin, 7 x 7 mm low-profile quad flat recommended footprint . . . . . . . . . . . . 109
Figure 44. LQFP48 marking example (package top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Figure 45. Standard WLCSP36 - 2.61 x 2.88 mm, 0.4 mm pitch wafer level chip scale
package outline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Figure 46. Standard WLCSP36 - 2.61 x 2.88 mm, 0.4 mm pitch wafer level chip scale
recommended footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Figure 47. Standard WLCSP36 marking example (package top view) . . . . . . . . . . . . . . . . . . . . . . . 113
Figure 48. Thin WLCSP36 - 2.61 x 2.88 mm, 0.4 mm pitch wafer level chip scale
package outline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Figure 49. Thin WLCSP36 - 2.61 x 2.88 mm, 0.4 mm pitch wafer level chip scale
package recommended footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Figure 50. LQFP32 - 32-pin, 7 x 7 mm low-profile quad flat package outline . . . . . . . . . . . . . . . . . . 116
Figure 51. LQFP32 - 32-pin, 7 x 7 mm low-profile quad flat recommended footprint . . . . . . . . . . . . 117
Figure 52. LQFP32 marking example (package top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Figure 53. UFQFPN32 - 32-pin, 5x5 mm, 0.5 mm pitch ultra thin fine pitch quad flat
package outline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Figure 54. UFQFPN32 - 32-pin, 5x5 mm, 0.5 mm pitch ultra thin fine pitch quad flat
recommended footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Figure 55. UFQFPN32 marking example (package top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Figure 56. Thermal resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
DS10184 Rev 9 9/132
STM32L051x6 STM32L051x8 Introduction
32
1 Introduction
The ultra-low-power STM32L051x6/8 are offered in 7 different package types: from 32 pins
to 64 pins. Depending on the device chosen, different sets of peripherals are included, the
description below gives an overview of the complete range of peripherals proposed in this
family.
These features make the ultra-low-power STM32L051x6/8 microcontrollers suitable for a
wide range of applications:
Gas/water meters and industrial sensors
Healthcare and fitness equipment
Remote control and user interface
PC peripherals, gaming, GPS equipment
Alarm system, wired and wireless sensors, video intercom
This STM32L051x6/8 datasheet should be read in conjunction with the STM32L0x1xx
reference manual (RM0377).
For information on the Arm®(a) Cortex
®
-M0+ core please refer to the Cortex
®
-M0+ Technical
Reference Manual, available from the www.arm.com website.
Figure 1 shows the general block diagram of the device family.
a. Arm is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.
Description STM32L051x6 STM32L051x8
10/132 DS10184 Rev 9
2 Description
The access line ultra-low-power STM32L051x6/8 microcontrollers incorporate the high-
performance Arm
®
Cortex
®
-M0+ 32-bit RISC core operating at a 32 MHz frequency, a
memory protection unit (MPU), high-speed embedded memories (
64
Kbytes of Flash
program memory,
2
Kbytes of data EEPROM and
8
Kbytes of RAM) plus an extensive range
of enhanced I/Os and peripherals.
The STM32L051x6/8 devices provide high power efficiency for a wide range of
performance. It is achieved with a large choice of internal and external clock sources, an
internal voltage adaptation and several low-power modes.
The STM32L051x6/8 devices offer several analog features, one 12-bit ADC with hardware
oversampling, two ultra-low-power comparators, several timers, one low-power timer
(LPTIM), three general-purpose 16-bit timers and one basic timer, one RTC and one
SysTick which can be used as timebases. They also feature two watchdogs, one watchdog
with independent clock and window capability and one window watchdog based on bus
clock.
Moreover, the STM32L051x6/8 devices embed standard and advanced communication
interfaces: up to two I2C, two SPIs, one I2S, two USARTs, a low-power UART (LPUART), .
The STM32L051x6/8 also include a real-time clock and a set of backup registers that
remain powered in Standby mode.
The ultra-low-power STM32L051x6/8 devices operate from a 1.8 to 3.6 V power supply
(down to 1.65 V at power down) with BOR and from a 1.65 to 3.6 V power supply without
BOR option. They are available in the -40 to +125 °C temperature range. A comprehensive
set of power-saving modes allows the design of low-power applications.
DS10184 Rev 9 11/132
STM32L051x6 STM32L051x8 Description
32
2.1 Device overview
Table 2. Ultra-low-power STM32L051x6/x8 device features and peripheral counts
Peripheral STM32
L051K6
STM32L
051T6
STM32
L051C6
STM32
L051R6
STM32
L051K8
STM32L
051T8
STM32
L051C8
STM32
L051R8
Flash (Kbytes) 32 64
Data EEPROM (Kbytes) 22
RAM (Kbytes) 88
Timers
General-
purpose 33
Basic 11
LPTIMER 11
RTC/SYSTICK/IWDG/
WWDG 1/1/1/1 1/1/1/1
Communi-
cation
interfaces
SPI/I2S 3(2)(1)/0 3(2)(1)/0 4(2)(1)/1 4(2)(1)/1 3(2)(1)/0 3(2)(1)/0 4(2)(1)/1 4(2)(1)/1
I2C1 222 1 222
USART 22
LPUART 0 111 0 111
GPIOs 27(2) 29 37 51(3) 27(2) 29 37 51(3)
Clocks:
HSE/LSE/HSI/MSI/LSI 0/1/1/1/1 0/1/1/1/1 1/1/1/1/1 1/1/1/1/1 0/1/1/1/1 0/1/1/1/1 1/1/1/1/1 1/1/1/1/1
12-bit synchronized ADC
Number of channels
1
10
1
10
1
10
1
16(3)
1
10
1
10
1
10
1
16(3)
Comparators 22
Max. CPU frequency 32 MHz
Operating voltage 1.8 V to 3.6 V (down to 1.65 V at power-down) with BOR option
1.65 V to 3.6 V without BOR option
Operating temperatures Ambient temperature: –40 to +125 °C
Junction temperature: –40 to +130 °C
Packages
LQFP32,
UFQFPN
32
WLCSP
36 LQFP48
LQFP64
TFBGA
64
LQFP32,
UFQFPN
32
WLCSP
36 LQFP48
LQFP64
TFBGA
64
1. 2 SPI interfaces are USARTs operating in SPI master mode.
2. LQFP32 has two GPIOs, less than UFQFPN32 (27).
3. TFBGA64 has one GPIO, one ADC input and one capacitive sensing channel less than LQFP64.
Description STM32L051x6 STM32L051x8
12/132 DS10184 Rev 9
Figure 1. STM32L051x6/8 block diagram
CORTEX M0+ CPU
Fmax:32MHz
SWD
MPU
NVIC
GPIO PORT A
GPIO PORT B
GPIO PORT C
GPIO PORT D
GPIO PORT H
Temp
sensor
RESET & CLK
FLASH
EEPROM
BOOT
RAM
DMA1
AHB: Fmax 32MHz
CRC
BRIDGE
A
P
B
2
FIREWALL
DBG
EXTI
ADC1
SPI1
USART1
TIM21
COMP1
LSE
TIM22
BRIDGE
A
P
B
1
TIM6
I2C1
I2C2
USART2
LPUART1
SPI2/I2S
TIM2
IWDG
RTC
WWDG
LPTIM1
BCKP REG
HSE HSI 16M
PLL
MSI
LSI
PMU
REGULATOR
VDD
VDDA
VREF_OUT
NRST
PVD_IN
OSC32_IN,
OSC32_OUT
OSC_IN,
OSC_OUT
WKUPx
PA[0:15]
PH[0:1]
PD[2]
PC[0:15]
PB[0:15]
AINx
MISO, MOSI,
SCK, NSS
RX, TX, RTS,
CTS, CK
2ch
2ch
INP, INM, OUT
IN1, IN2,
ETR, OUT
SCL, SDA,
SMBA
SCL, SDA,
SMBA
RX, TX, RTS,
CTS, CK
RX, TX, RTS,
CTS
MISO/MCK,
MOSI/SD,
SCK/CK, NSS/
WS
4ch
SWD
MS33389V2
COMP2 INP, INM, OUT
DS10184 Rev 9 13/132
STM32L051x6 STM32L051x8 Description
32
2.2 Ultra-low-power device continuum
The ultra-low-power family offers a large choice of core and features, from 8-bit proprietary
core up to Arm
®
Cortex
®
-M4, including Arm
®
Cortex
®
-M3 and Arm
®
Cortex
®
-M0+. The
STM32Lx series are the best choice to answer your needs in terms of ultra-low-power
features. The STM32 ultra-low-power series are the best solution for applications such as
gaz/water meter, keyboard/mouse or fitness and healthcare application. Several built-in
features like LCD drivers, dual-bank memory, low-power run mode, operational amplifiers,
128-bit AES, DAC, crystal-less USB and many other definitely help you building a highly
cost optimized application by reducing BOM cost. STMicroelectronics, as a reliable and
long-term manufacturer, ensures as much as possible pin-to-pin compatibility between all
STM8Lx and STM32Lx on one hand, and between all STM32Lx and STM32Fx on the other
hand. Thanks to this unprecedented scalability, your legacy application can be upgraded to
respond to the latest market feature and efficiency requirements.
Functional overview STM32L051x6 STM32L051x8
14/132 DS10184 Rev 9
3 Functional overview
3.1 Low-power modes
The ultra-low-power STM32L051x6/8 support dynamic voltage scaling to optimize its power
consumption in Run mode. The voltage from the internal low-drop regulator that supplies
the logic can be adjusted according to the system’s maximum operating frequency and the
external voltage supply.
There are three power consumption ranges:
Range 1 (VDD range limited to 1.71-3.6 V), with the CPU running at up to 32 MHz
Range 2 (full VDD range), with a maximum CPU frequency of 16 MHz
Range 3 (full VDD range), with a maximum CPU frequency limited to 4.2 MHz
Seven low-power modes are provided to achieve the best compromise between low-power
consumption, short startup time and available wakeup sources:
Sleep mode
In Sleep mode, only the CPU is stopped. All peripherals continue to operate and can
wake up the CPU when an interrupt/event occurs. Sleep mode power consumption at
16 MHz is about 1 mA with all peripherals off.
Low-power run mode
This mode is achieved with the multispeed internal (MSI) RC oscillator set to the low-
speed clock (max 131 kHz), execution from SRAM or Flash memory, and internal
regulator in low-power mode to minimize the regulator's operating current. In Low-
power run mode, the clock frequency and the number of enabled peripherals are both
limited.
Low-power sleep mode
This mode is achieved by entering Sleep mode with the internal voltage regulator in
low-power mode to minimize the regulator’s operating current. In Low-power sleep
mode, both the clock frequency and the number of enabled peripherals are limited; a
typical example would be to have a timer running at 32 kHz.
When wakeup is triggered by an event or an interrupt, the system reverts to the Run
mode with the regulator on.
Stop mode with RTC
The Stop mode achieves the lowest power consumption while retaining the RAM and
register contents and real time clock. All clocks in the VCORE domain are stopped, the
PLL, MSI RC, HSE crystal and HSI RC oscillators are disabled. The LSE or LSI is still
running. The voltage regulator is in the low-power mode.
Some peripherals featuring wakeup capability can enable the HSI RC during Stop
mode to detect their wakeup condition.
The device can be woken up from Stop mode by any of the EXTI line, in 3.5 µs, the
processor can serve the interrupt or resume the code. The EXTI line source can be any
GPIO. It can be the PVD output, the comparator 1 event or comparator 2 event
(if internal reference voltage is on), it can be the RTC alarm/tamper/timestamp/wakeup
events, the USART/I2C/LPUART/LPTIMER wakeup events.
DS10184 Rev 9 15/132
STM32L051x6 STM32L051x8 Functional overview
32
Stop mode without RTC
The Stop mode achieves the lowest power consumption while retaining the RAM and
register contents. All clocks are stopped, the PLL, MSI RC, HSI and LSI RC, HSE and
LSE crystal oscillators are disabled.
Some peripherals featuring wakeup capability can enable the HSI RC during Stop
mode to detect their wakeup condition.
The voltage regulator is in the low-power mode. The device can be woken up from Stop
mode by any of the EXTI line, in 3.5 µs, the processor can serve the interrupt or
resume the code. The EXTI line source can be any GPIO. It can be the PVD output, the
comparator 1 event or comparator 2 event (if internal reference voltage is on). It can
also be wakened by the USART/I2C/LPUART/LPTIMER wakeup events.
Standby mode with RTC
The Standby mode is used to achieve the lowest power consumption and real time
clock. The internal voltage regulator is switched off so that the entire VCORE domain is
powered off. The PLL, MSI RC, HSE crystal and HSI RC oscillators are also switched
off. The LSE or LSI is still running. After entering Standby mode, the RAM and register
contents are lost except for registers in the Standby circuitry (wakeup logic, IWDG,
RTC, LSI, LSE Crystal 32 KHz oscillator, RCC_CSR register).
The device exits Standby mode in 60 µs when an external reset (NRST pin), an IWDG
reset, a rising edge on one of the three WKUP pins, RTC alarm (Alarm A or Alarm B),
RTC tamper event, RTC timestamp event or RTC Wakeup event occurs.
Standby mode without RTC
The Standby mode is used to achieve the lowest power consumption. The internal
voltage regulator is switched off so that the entire VCORE domain is powered off. The
PLL, MSI RC, HSI and LSI RC, HSE and LSE crystal oscillators are also switched off.
After entering Standby mode, the RAM and register contents are lost except for
registers in the Standby circuitry (wakeup logic, IWDG, RTC, LSI, LSE Crystal 32 KHz
oscillator, RCC_CSR register).
The device exits Standby mode in 60 µs when an external reset (NRST pin) or a rising
edge on one of the three WKUP pin occurs.
Note: The RTC, the IWDG, and the corresponding clock sources are not stopped automatically by
entering Stop or Standby mode.
Table 3. Functionalities depending on the operating power supply range
Operating power supply range(1)
Functionalities depending on the operating power
supply range
ADC operation Dynamic voltage scaling
range
VDD = 1.65 to 1.71 V ADC only, conversion time
up to 570 ksps
Range 2 or
range 3
VDD = 1.71 to 1.8 V(2) ADC only, conversion time
up to 1.14 Msps Range 1, range 2 or range 3
VDD = 1.8 to 2.0 V(2) Conversion time up to 1.14
Msps Range1, range 2 or range 3
Functional overview STM32L051x6 STM32L051x8
16/132 DS10184 Rev 9
VDD = 2.0 to 2.4 V Conversion time up to 1.14
Msps Range 1, range 2 or range 3
VDD = 2.4 to 3.6 V Conversion time up to 1.14
Msps Range 1, range 2 or range 3
1. GPIO speed depends on VDD voltage. Refer to Table 58: I/O AC characteristics for more information about
I/O speed.
2. CPU frequency changes from initial to final must respect "fcpu initial <4*fcpu final". It must also respect 5
μs delay between two changes. For example to switch from 4.2 MHz to 32 MHz, you can switch from 4.2
MHz to 16 MHz, wait 5 μs, then switch from 16 MHz to 32 MHz.
Table 4. CPU frequency range depending on dynamic voltage scaling
CPU frequency range Dynamic voltage scaling range
16 MHz to 32 MHz (1ws)
32 kHz to 16 MHz (0ws) Range 1
8 MHz to 16 MHz (1ws)
32 kHz to 8 MHz (0ws) Range 2
32 kHz to 4.2 MHz (0ws) Range 3
Table 3. Functionalities depending on the operating power supply range (continued)
Operating power supply range(1)
Functionalities depending on the operating power
supply range
ADC operation Dynamic voltage scaling
range
Table 5. Functionalities depending on the working mode
(from Run/active down to standby) (1)
IPs Run/Active Sleep
Low-
power
run
Low-
power
sleep
Stop Standby
Wakeup
capability
Wakeup
capability
CPU Y -- Y -- -- --
Flash memory O O O O -- --
RAM Y Y Y Y Y --
Backup registers Y Y Y Y Y Y
EEPROM O O O O -- --
Brown-out reset
(BOR) OOOOOOOO
DMA O O O O -- --
Programmable
Voltage Detector
(PVD)
OOOOOO-
Power-on/down
reset (POR/PDR) YYYYYYYY
DS10184 Rev 9 17/132
STM32L051x6 STM32L051x8 Functional overview
32
High Speed
Internal (HSI) OO----
(2) --
High Speed
External (HSE) OOOO-- --
Low Speed Internal
(LSI) OOOOO O
Low Speed
External (LSE) OOOOO O
Multi-Speed
Internal (MSI) OOYY-- --
Inter-Connect
Controller YYYYY --
RTC O O O O O O O
RTC Tamper O O O O O O O O
Auto WakeUp
(AWU) OOOOOOOO
USART O O O O O(3) O--
LPUART O O O O O(3) O--
SPI O O O O -- --
I2C O O -- -- O(4) O--
ADC O O -- -- -- --
Temperature
sensor OOOOO --
Comparators O O O O O O --
16-bit timers O O O O -- --
LPTIMER O O O O O O
IWDG O O O O O O O O
WWDG O O O O -- --
SysTick Timer O O O O --
GPIOs O O O O O O 2 pins
Wakeup time to
Run mode 0 µs 0.36 µs 3 µs 32 µs 3.5 µs 50 µs
Table 5. Functionalities depending on the working mode
(from Run/active down to standby) (continued)(1)
IPs Run/Active Sleep
Low-
power
run
Low-
power
sleep
Stop Standby
Wakeup
capability
Wakeup
capability
Functional overview STM32L051x6 STM32L051x8
18/132 DS10184 Rev 9
3.2 Interconnect matrix
Several peripherals are directly interconnected. This allows autonomous communication
between peripherals, thus saving CPU resources and power consumption. In addition,
these hardware connections allow fast and predictable latency.
Depending on peripherals, these interconnections can operate in Run, Sleep, Low-power
run, Low-power sleep and Stop modes.
Consumption
VDD=1.8 to 3.6 V
(Typ)
Down to
140 µA/MHz
(from Flash
memory)
Down to
37 µA/MHz
(from Flash
memory)
Down to
8 µA
Down to
4.5 µA
0.4 µA (No
RTC) VDD=1.8 V
0.28 µA (No
RTC) VDD=1.8 V
0.8 µA (with
RTC) VDD=1.8 V
0.65 µA (with
RTC) VDD=1.8 V
0.4 µA (No
RTC) VDD=3.0 V
0.29 µA (No
RTC) VDD=3.0 V
1 µA (with RTC)
VDD=3.0 V
0.85 µA (with
RTC) VDD=3.0 V
1. Legend:
“Y” = Yes (enable).
“O” = Optional can be enabled/disabled by software)
“-” = Not available
2. Some peripherals with wakeup from Stop capability can request HSI to be enabled. In this case, HSI is woken up by the
peripheral, and only feeds the peripheral which requested it. HSI is automatically put off when the peripheral does not need
it anymore.
3. UART and LPUART reception is functional in Stop mode. It generates a wakeup interrupt on Start. To generate a wakeup
on address match or received frame event, the LPUART can run on LSE clock while the UART has to wake up or keep
running the HSI clock.
4. I2C address detection is functional in Stop mode. It generates a wakeup interrupt in case of address match. It will wake up
the HSI during reception.
Table 5. Functionalities depending on the working mode
(from Run/active down to standby) (continued)(1)
IPs Run/Active Sleep
Low-
power
run
Low-
power
sleep
Stop Standby
Wakeup
capability
Wakeup
capability
Table 6. STM32L0xx peripherals interconnect matrix
Interconnect
source
Interconnect
destination Interconnect action Run Sleep
Low-
power
run
Low-
power
sleep
Stop
COMPx
TIM2,TIM21,
TIM22
Timer input channel,
trigger from analog
signals comparison
YY Y Y -
LPTIM
Timer input channel,
trigger from analog
signals comparison
YY Y Y Y
TIMx TIMx Timer triggered by other
timer YY Y Y -
DS10184 Rev 9 19/132
STM32L051x6 STM32L051x8 Functional overview
32
3.3 Arm® Cortex
®
-M0+ core with MPU
The Cortex-M0+ processor is an entry-level 32-bit Arm Cortex processor designed for a
broad range of embedded applications. It offers significant benefits to developers, including:
a simple architecture that is easy to learn and program
ultra-low power, energy-efficient operation
excellent code density
deterministic, high-performance interrupt handling
upward compatibility with Cortex-M processor family
platform security robustness, with integrated Memory Protection Unit (MPU).
The Cortex-M0+ processor is built on a highly area and power optimized 32-bit processor
core, with a 2-stage pipeline Von Neumann architecture. The processor delivers exceptional
energy efficiency through a small but powerful instruction set and extensively optimized
design, providing high-end processing hardware including a single-cycle multiplier.
The Cortex-M0+ processor provides the exceptional performance expected of a modern 32-
bit architecture, with a higher code density than other 8-bit and 16-bit microcontrollers.
Owing to its embedded Arm core, the STM32L051x6/8 are compatible with all Arm tools and
software.
RTC
TIM21 Timer triggered by Auto
wake-up YY Y Y -
LPTIM Timer triggered by RTC
event YY Y Y Y
All clock
source TIMx
Clock source used as
input channel for RC
measurement and
trimming
YY Y Y -
GPIO
TIMx Timer input channel and
trigger YY Y Y -
LPTIM Timer input channel and
trigger YY Y Y Y
ADC Conversion trigger Y Y Y Y -
Table 6. STM32L0xx peripherals interconnect matrix (continued)
Interconnect
source
Interconnect
destination Interconnect action Run Sleep
Low-
power
run
Low-
power
sleep
Stop
Functional overview STM32L051x6 STM32L051x8
20/132 DS10184 Rev 9
Nested vectored interrupt controller (NVIC)
The ultra-low-power STM32L051x6/8 embed a nested vectored interrupt controller able to
handle up to 32 maskable interrupt channels and 4 priority levels.
The Cortex-M0+ processor closely integrates a configurable Nested Vectored Interrupt
Controller (NVIC), to deliver industry-leading interrupt performance. The NVIC:
includes a Non-Maskable Interrupt (NMI)
provides zero jitter interrupt option
provides four interrupt priority levels
The tight integration of the processor core and NVIC provides fast execution of Interrupt
Service Routines (ISRs), dramatically reducing the interrupt latency. This is achieved
through the hardware stacking of registers, and the ability to abandon and restart load-
multiple and store-multiple operations. Interrupt handlers do not require any assembler
wrapper code, removing any code overhead from the ISRs. Tail-chaining optimization also
significantly reduces the overhead when switching from one ISR to another.
To optimize low-power designs, the NVIC integrates with the sleep modes, that include a
deep sleep function that enables the entire device to enter rapidly stop or standby mode.
This hardware block provides flexible interrupt management features with minimal interrupt
latency.
3.4 Reset and supply management
3.4.1 Power supply schemes
VDD = 1.65 to 3.6 V: external power supply for I/Os and the internal regulator. Provided
externally through VDD pins.
VSSA, VDDA = 1.65 to 3.6 V: external analog power supplies for ADC reset blocks, RCs
and PLL. VDDA and VSSA must be connected to VDD and VSS, respectively.
3.4.2 Power supply supervisor
The devices have an integrated ZEROPOWER power-on reset (POR)/power-down reset
(PDR) that can be coupled with a brownout reset (BOR) circuitry.
Two versions are available:
The version with BOR activated at power-on operates between 1.8 V and 3.6 V.
The other version without BOR operates between 1.65 V and 3.6 V.
After the VDD threshold is reached (1.65 V or 1.8 V depending on the BOR which is active or
not at power-on), the option byte loading process starts, either to confirm or modify default
thresholds, or to disable the BOR permanently: in this case, the VDD min value becomes
1.65 V (whatever the version, BOR active or not, at power-on).
When BOR is active at power-on, it ensures proper operation starting from 1.8 V whatever
the power ramp-up phase before it reaches 1.8 V. When BOR is not active at power-up, the
power ramp-up should guarantee that 1.65 V is reached on VDD at least 1 ms after it exits
the POR area.
Five BOR thresholds are available through option bytes, starting from 1.8 V to 3 V. To
reduce the power consumption in Stop mode, it is possible to automatically switch off the
DS10184 Rev 9 21/132
STM32L051x6 STM32L051x8 Functional overview
32
internal reference voltage (VREFINT) in Stop mode. The device remains in reset mode when
VDD is below a specified threshold, VPOR/PDR or VBOR, without the need for any external
reset circuit.
Note: The start-up time at power-on is typically 3.3 ms when BOR is active at power-up, the start-
up time at power-on can be decreased down to 1 ms typically for devices with BOR inactive
at power-up.
The devices feature an embedded programmable voltage detector (PVD) that monitors the
VDD/VDDA power supply and compares it to the VPVD threshold. This PVD offers 7 different
levels between 1.85 V and 3.05 V, chosen by software, with a step around 200 mV. An
interrupt can be generated when VDD/VDDA drops below the VPVD threshold and/or when
VDD/VDDA is higher than the VPVD threshold. The interrupt service routine can then generate
a warning message and/or put the MCU into a safe state. The PVD is enabled by software.
3.4.3 Voltage regulator
The regulator has three operation modes: main (MR), low power (LPR) and power down.
MR is used in Run mode (nominal regulation)
LPR is used in the Low-power run, Low-power sleep and Stop modes
Power down is used in Standby mode. The regulator output is high impedance, the
kernel circuitry is powered down, inducing zero consumption but the contents of the
registers and RAM are lost except for the standby circuitry (wakeup logic, IWDG, RTC,
LSI, LSE crystal 32 KHz oscillator, RCC_CSR).
3.5 Clock management
The clock controller distributes the clocks coming from different oscillators to the core and
the peripherals. It also manages clock gating for low-power modes and ensures clock
robustness. It features:
Clock prescaler
To get the best trade-off between speed and current consumption, the clock frequency
to the CPU and peripherals can be adjusted by a programmable prescaler.
Safe clock switching
Clock sources can be changed safely on the fly in Run mode through a configuration
register.
Clock management
To reduce power consumption, the clock controller can stop the clock to the core,
individual peripherals or memory.
System clock source
Three different clock sources can be used to drive the master clock SYSCLK:
1-25 MHz high-speed external crystal (HSE), that can supply a PLL
16 MHz high-speed internal RC oscillator (HSI), trimmable by software, that can
supply a PLLMultispeed internal RC oscillator (MSI), trimmable by software, able
to generate 7 frequencies (65 kHz, 131 kHz, 262 kHz, 524 kHz, 1.05 MHz, 2.1
MHz, 4.2 MHz). When a 32.768 kHz clock source is available in the system (LSE),
the MSI frequency can be trimmed by software down to a ±0.5% accuracy.
Auxiliary clock source
Two ultra-low-power clock sources that can be used to drive the real-time clock:
Functional overview STM32L051x6 STM32L051x8
22/132 DS10184 Rev 9
32.768 kHz low-speed external crystal (LSE)
37 kHz low-speed internal RC (LSI), also used to drive the independent watchdog.
The LSI clock can be measured using the high-speed internal RC oscillator for
greater precision.
RTC clock source
The LSI, LSE or HSE sources can be chosen to clock the RTC, whatever the system
clock.
Startup clock
After reset, the microcontroller restarts by default with an internal 2 MHz clock (MSI).
The prescaler ratio and clock source can be changed by the application program as
soon as the code execution starts.
Clock security system (CSS)
This feature can be enabled by software. If an HSE clock failure occurs, the master
clock is automatically switched to HSI and a software interrupt is generated if enabled.
Another clock security system can be enabled, in case of failure of the LSE it provides
an interrupt or wakeup event which is generated if enabled.
Clock-out capability (MCO: microcontroller clock output)
It outputs one of the internal clocks for external use by the application.
Several prescalers allow the configuration of the AHB frequency, each APB (APB1 and
APB2) domains. The maximum frequency of the AHB and the APB domains is 32 MHz. See
Figure 2 for details on the clock tree.
DS10184 Rev 9 23/132
STM32L051x6 STM32L051x8 Functional overview
32
Figure 2. Clock tree
MSv34747V1
Legend:
HSE = High-speed external clock signal
HSI = High-speed internal clock signal
LSI = Low-speed internal clock signal
LSE = Low-speed external clock signal
MSI = Multispeed internal clock signal
Watchdog LS
LSI RC
LSE OSC RTC
LSI tempo
@V33
/ 1,2,4,8,16
HSI16 RC
Level shifters
HSE OSC
Level shifters
LSU
1 MHz Clock
Detector
LSD
/ 8
LSE tempo
MSI RC
Level shifters
/ 2,4,8,16
/ 2,3,4
Level shifters
PLL
X
3,4,6,8,12,16,
24,32,48
AHB
PRESC
/ 1,2,…, 512
Clock
Source
Control
@V33
@V33
@V33
@V33
@V18
@V18
@V18
@V18
I2C1CLK
LPUART/
UARTCLK
LPTIMCLK
LSE
HSI16
SYSCLK
PCLK
LSI
not (sleep or
deepsleep)
not (sleep or
deepsleep)
not deepsleep
not deepsleep
HCLK
TIMxCLK
CK_PWR
FCLK
PLLCLK
HSE
HSI16
MSI
LSE
LSI
HSE present or not
@V33
@V
DDCORE
ck_rchs
/ 1,4
HSI16
MSI
1 MHz
ck_pllin
Enable Watchdog
RTC2 enable
ADC enable
ADCCLK
LSU LSD LSD
MCO
MCOSEL
PLLSRC
RTCSEL
System
Clock
Peripherals
enable
Peripherals
enable
Peripheral
clock enable
PCLK1 to APB1
peripherals
If (APB1 presc=1) x1
else x2)
to TIMx
Peripheral
clock enable
APB2
PRESC
/ 1,2,4,8,16
Peripheral
clock enable
PCLK2 to APB2
peripherals
32 MHz
max.
If (APB2 presc=1) x1
else x2)
to TIMx
Peripherals
enable
APB1
PRESC
/ 1,2,4,8,16
Functional overview STM32L051x6 STM32L051x8
24/132 DS10184 Rev 9
3.6 Low-power real-time clock and backup registers
The real time clock (RTC) and the 5 backup registers are supplied in all modes including
standby mode. The backup registers are five 32-bit registers used to store 20 bytes of user
application data. They are not reset by a system reset, or when the device wakes up from
Standby mode.
The RTC is an independent BCD timer/counter. Its main features are the following:
Calendar with subsecond, seconds, minutes, hours (12 or 24 format), week day, date,
month, year, in BCD (binary-coded decimal) format
Automatically correction for 28, 29 (leap year), 30, and 31 day of the month
Two programmable alarms with wake up from Stop and Standby mode capability
Periodic wakeup from Stop and Standby with programmable resolution and period
On-the-fly correction from 1 to 32767 RTC clock pulses. This can be used to
synchronize it with a master clock.
Reference clock detection: a more precise second source clock (50 or 60 Hz) can be
used to enhance the calendar precision.
Digital calibration circuit with 1 ppm resolution, to compensate for quartz crystal
inaccuracy
2 anti-tamper detection pins with programmable filter. The MCU can be woken up from
Stop and Standby modes on tamper event detection.
Timestamp feature which can be used to save the calendar content. This function can
be triggered by an event on the timestamp pin, or by a tamper event. The MCU can be
woken up from Stop and Standby modes on timestamp event detection.
The RTC clock sources can be:
A 32.768 kHz external crystal
A resonator or oscillator
The internal low-power RC oscillator (typical frequency of 37 kHz)
The high-speed external clock
3.7 General-purpose inputs/outputs (GPIOs)
Each of the GPIO pins can be configured by software as output (push-pull or open-drain), as
input (with or without pull-up or pull-down) or as peripheral alternate function. Most of the
GPIO pins are shared with digital or analog alternate functions, and can be individually
remapped using dedicated alternate function registers. All GPIOs are high current capable.
Each GPIO output, speed can be slowed (40 MHz, 10 MHz, 2 MHz, 400 kHz). The alternate
function configuration of I/Os can be locked if needed following a specific sequence in order
to avoid spurious writing to the I/O registers. The I/O controller is connected to a dedicated
IO bus with a toggling speed of up to 32 MHz.
Extended interrupt/event controller (EXTI)
The extended interrupt/event controller consists of 28 edge detector lines used to generate
interrupt/event requests. Each line can be individually configured to select the trigger event
(rising edge, falling edge, both) and can be masked independently. A pending register
maintains the status of the interrupt requests. The EXTI can detect an external line with a
pulse width shorter than the Internal APB2 clock period. Up to 51 GPIOs can be connected
to the 16 configurable interrupt/event lines. The 12 other lines are connected to PVD, RTC,
USARTs, LPUART, LPTIMER or comparator events.
DS10184 Rev 9 25/132
STM32L051x6 STM32L051x8 Functional overview
32
3.8 Memories
The STM32L051x6/8 devices have the following features:
8 Kbytes of embedded SRAM accessed (read/write) at CPU clock speed with 0 wait
states. With the enhanced bus matrix, operating the RAM does not lead to any
performance penalty during accesses to the system bus (AHB and APB buses).
The non-volatile memory is divided into three arrays:
32 or 64 Kbytes of embedded Flash program memory
2 Kbytes of data EEPROM
Information block containing 32 user and factory options bytes plus 4 Kbytes of
system memory
The user options bytes are used to write-protect or read-out protect the memory (with
4 Kbyte granularity) and/or readout-protect the whole memory with the following options:
Level 0: no protection
Level 1: memory readout protected.
The Flash memory cannot be read from or written to if either debug features are
connected or boot in RAM is selected
Level 2: chip readout protected, debug features (Cortex-M0+ serial wire) and boot in
RAM selection disabled (debugline fuse)
The firewall protects parts of code/data from access by the rest of the code that is executed
outside of the protected area. The granularity of the protected code segment or the non-
volatile data segment is 256 bytes (Flash memory or EEPROM) against 64 bytes for the
volatile data segment (RAM).
The whole non-volatile memory embeds the error correction code (ECC) feature.
3.9 Boot modes
At startup, BOOT0 pin and nBOOT1 option bit are used to select one of three boot options:
Boot from Flash memory
Boot from System memory
Boot from embedded RAM
The boot loader is located in System memory. It is used to reprogram the Flash memory by
using SPI1(PA4, PA5, PA6, PA7) or SPI2 (PB12, PB13, PB14, PB15), USART1(PA9,
PA10) or USART2(PA2, PA3). See STM32™ microcontroller system memory boot mode
AN2606 for details.
Functional overview STM32L051x6 STM32L051x8
26/132 DS10184 Rev 9
3.10 Direct memory access (DMA)
The flexible 7-channel, general-purpose DMA is able to manage memory-to-memory,
peripheral-to-memory and memory-to-peripheral transfers. The DMA controller supports
circular buffer management, avoiding the generation of interrupts when the controller
reaches the end of the buffer.
Each channel is connected to dedicated hardware DMA requests, with software trigger
support for each channel. Configuration is done by software and transfer sizes between
source and destination are independent.
The DMA can be used with the main peripherals: SPI, I2C, USART, LPUART,
general-purpose timers, and ADC.
3.11 Analog-to-digital converter (ADC)
A native 12-bit, extended to 16-bit through hardware oversampling, analog-to-digital
converter is embedded into STM32L051x6/8 device. It has up to 16 external channels and 3
internal channels (temperature sensor, voltage reference). Three channels, PA0, PA4 and
PA5, are fast channels, while the others are standard channels.
The ADC performs conversions in single-shot or scan mode. In scan mode, automatic
conversion is performed on a selected group of analog inputs.
The ADC frequency is independent from the CPU frequency, allowing maximum sampling
rate of 1.14 MSPS even with a low CPU speed. The ADC consumption is low at all
frequencies (~25 µA at 10 kSPS, ~200 µA at 1MSPS). An auto-shutdown function
guarantees that the ADC is powered off except during the active conversion phase.
The ADC can be served by the DMA controller. It can operate from a supply voltage down to
1.65 V.
The ADC features a hardware oversampler up to 256 samples, this improves the resolution
to 16 bits (see AN2668).
An analog watchdog feature allows very precise monitoring of the converted voltage of one,
some or all scanned channels. An interrupt is generated when the converted voltage is
outside the programmed thresholds.
The events generated by the general-purpose timers (TIMx) can be internally connected to
the ADC start triggers, to allow the application to synchronize A/D conversions and timers.
3.12 Temperature sensor
The temperature sensor (TSENSE) generates a voltage VSENSE that varies linearly with
temperature.
The temperature sensor is internally connected to the ADC_IN18 input channel which is
used to convert the sensor output voltage into a digital value.
The sensor provides good linearity but it has to be calibrated to obtain good overall
accuracy of the temperature measurement. As the offset of the temperature sensor varies
from chip to chip due to process variation, the uncalibrated internal temperature sensor is
suitable for applications that detect temperature changes only.
DS10184 Rev 9 27/132
STM32L051x6 STM32L051x8 Functional overview
32
To improve the accuracy of the temperature sensor measurement, each device is
individually factory-calibrated by ST. The temperature sensor factory calibration data are
stored by ST in the system memory area, accessible in read-only mode.
3.12.1 Internal voltage reference (VREFINT)
The internal voltage reference (VREFINT) provides a stable (bandgap) voltage output for the
ADC and Comparators. VREFINT is internally connected to the ADC_IN17 input channel. It
enables accurate monitoring of the VDD value (when no external voltage, VREF+, is available
for ADC). The precise voltage of VREFINT is individually measured for each part by ST during
production test and stored in the system memory area. It is accessible in read-only mode.
3.13 Ultra-low-power comparators and reference voltage
The STM32L051x6/8 embed two comparators sharing the same current bias and reference
voltage. The reference voltage can be internal or external (coming from an I/O).
One comparator with ultra low consumption
One comparator with rail-to-rail inputs, fast or slow mode.
The threshold can be one of the following:
External I/O pins
Internal reference voltage (VREFINT)
submultiple of Internal reference voltage(1/4, 1/2, 3/4) for the rail to rail
comparator.
Both comparators can wake up the devices from Stop mode, and be combined into a
window comparator.
The internal reference voltage is available externally via a low-power / low-current output
buffer (driving current capability of 1 µA typical).
Table 7. Temperature sensor calibration values
Calibration value name Description Memory address
TSENSE_CAL1
TS ADC raw data acquired at
temperature of 30 °C,
VDDA= 3 V
0x1FF8 007A - 0x1FF8 007B
TSENSE_CAL2
TS ADC raw data acquired at
temperature of 130 °C
VDDA= 3 V
0x1FF8 007E - 0x1FF8 007F
Table 8. Internal voltage reference measured values
Calibration value name Description Memory address
VREFINT_CAL
Raw data acquired at
temperature of 25 °C
VDDA = 3 V
0x1FF8 0078 - 0x1FF8 0079
Functional overview STM32L051x6 STM32L051x8
28/132 DS10184 Rev 9
3.14 System configuration controller
The system configuration controller provides the capability to remap some alternate
functions on different I/O ports.
The highly flexible routing interface allows the application firmware to control the routing of
different I/Os to the TIM2, TIM21, TIM22 and LPTIM timer input captures. It also controls the
routing of internal analog signals to ADC, COMP1 and COMP2 and the internal reference
voltage VREFINT.
3.15 Timers and watchdogs
The ultra-low-power STM32L051x6/8 devices include three general-purpose timers, one
low- power timer (LPTIM), one basic timer, two watchdog timers and the SysTick timer.
Table 9 compares the features of the general-purpose and basic timers.
3.15.1 General-purpose timers (TIM2, TIM21 and TIM22)
There are three synchronizable general-purpose timers embedded in the STM32L051x6/8
devices (see Table 9 for differences).
TIM2
TIM2 is based on 16-bit auto-reload up/down counter. It includes a 16-bit prescaler. It
features four independent channels each for input capture/output compare, PWM or one-
pulse mode output.
The TIM2 general-purpose timers can work together or with the TIM21 and TIM22 general-
purpose timers via the Timer Link feature for synchronization or event chaining. Their
counter can be frozen in debug mode. Any of the general-purpose timers can be used to
generate PWM outputs.
TIM2 has independent DMA request generation.
This timer is capable of handling quadrature (incremental) encoder signals and the digital
outputs from 1 to 3 hall-effect sensors.
TIM21 and TIM22
TIM21 and TIM22 are based on a 16-bit auto-reload up/down counter. They include a 16-bit
prescaler. They have two independent channels for input capture/output compare, PWM or
Table 9. Timer feature comparison
Timer Counter
resolution Counter type Prescaler factor
DMA
request
generation
Capture/compare
channels
Complementary
outputs
TIM2 16-bit Up, down,
up/down
Any integer between
1 and 65536 Yes 4 No
TIM21,
TIM22 16-bit Up, down,
up/down
Any integer between
1 and 65536 No 2 No
TIM6 16-bit Up Any integer between
1 and 65536 Yes 0 No
DS10184 Rev 9 29/132
STM32L051x6 STM32L051x8 Functional overview
32
one-pulse mode output. They can work together and be synchronized with the TIM2, full-
featured general-purpose timers.
They can also be used as simple time bases and be clocked by the LSE clock source
(32.768 kHz) to provide time bases independent from the main CPU clock.
3.15.2 Low-power Timer (LPTIM)
The low-power timer has an independent clock and is running also in Stop mode if it is
clocked by LSE, LSI or an external clock. It is able to wakeup the devices from Stop mode.
This low-power timer supports the following features:
16-bit up counter with 16-bit autoreload register
16-bit compare register
Configurable output: pulse, PWM
Continuous / one shot mode
Selectable software / hardware input trigger
Selectable clock source
Internal clock source: LSE, LSI, HSI or APB clock
External clock source over LPTIM input (working even with no internal clock
source running, used by the Pulse Counter Application)
Programmable digital glitch filter
Encoder mode
3.15.3 Basic timer (TIM6)
This timer can be used as a generic 16-bit timebase.
3.15.4 SysTick timer
This timer is dedicated to the OS, but could also be used as a standard downcounter. It is
based on a 24-bit downcounter with autoreload capability and a programmable clock
source. It features a maskable system interrupt generation when the counter reaches ‘0’.
3.15.5 Independent watchdog (IWDG)
The independent watchdog is based on a 12-bit downcounter and 8-bit prescaler. It is
clocked from an independent 37 kHz internal RC and, as it operates independently of the
main clock, it can operate in Stop and Standby modes. It can be used either as a watchdog
to reset the device when a problem occurs, or as a free-running timer for application timeout
management. It is hardware- or software-configurable through the option bytes. The counter
can be frozen in debug mode.
3.15.6 Window watchdog (WWDG)
The window watchdog is based on a 7-bit downcounter that can be set as free-running. It
can be used as a watchdog to reset the device when a problem occurs. It is clocked from
the main clock. It has an early warning interrupt capability and the counter can be frozen in
debug mode.
Functional overview STM32L051x6 STM32L051x8
30/132 DS10184 Rev 9
3.16 Communication interfaces
3.16.1 I2C bus
two I2C interface (I2C1, I2C2) can operate in multimaster or slave modes.
Each I2C interface can support Standard mode (Sm, up to 100 kbit/s), Fast mode (Fm, up to
400 kbit/s) and Fast Mode Plus (Fm+, up to 1 Mbit/s) with 20 mA output drive on some I/Os.
7-bit and 10-bit addressing modes, multiple 7-bit slave addresses (2 addresses, 1 with
configurable mask) are also supported as well as programmable analog and digital noise
filters.
In addition, I2C1 provides hardware support for SMBus 2.0 and PMBus 1.1: ARP capability,
Host notify protocol, hardware CRC (PEC) generation/verification, timeouts verifications and
ALERT protocol management. I2C1 also has a clock domain independent from the CPU
clock, allowing the I2C1 to wake up the MCU from Stop mode on address match.
Each I2C interface can be served by the DMA controller.
Refer to Table 11 for an overview of I2C interface features.
Table 10. Comparison of I2C analog and digital filters
Analog filter Digital filter
Pulse width of
suppressed spikes 50 ns Programmable length from 1 to 15
I2C peripheral clocks
Benefits Available in Stop mode
1. Extra filtering capability vs.
standard requirements.
2. Stable length
Drawbacks Variations depending on
temperature, voltage, process
Wakeup from Stop on address
match is not available when digital
filter is enabled.
Table 11. STM32L051x6/8 I2C implementation
I2C features(1)
1. X = supported.
I2C1 I2C2
7-bit addressing mode X X
10-bit addressing mode X X
Standard mode (up to 100 kbit/s) X X
Fast mode (up to 400 kbit/s) X X
Fast Mode Plus with 20 mA output drive I/Os (up to 1 Mbit/s) X X(2)
2. See for the list of I/Os that feature Fast Mode Plus capability
Independent clock X -
SMBus X -
Wakeup from STOP X -
DS10184 Rev 9 31/132
STM32L051x6 STM32L051x8 Functional overview
32
3.16.2 Universal synchronous/asynchronous receiver transmitter (USART)
The two USART interfaces (USART1, USART2) are able to communicate at speeds of up to
4 Mbit/s.
They provide hardware management of the CTS, RTS and RS485 driver enable (DE)
signals, multiprocessor communication mode, master synchronous communication and
single-wire half-duplex communication mode. They also support SmartCard communication
(ISO 7816), IrDA SIR ENDEC, LIN Master/Slave capability, auto baud rate feature and has
a clock domain independent from the CPU clock, allowing to wake up the MCU from Stop
mode using baudrates up to 42 Kbaud.
All USART interfaces can be served by the DMA controller.
Table 12 for the supported modes and features of USART interfaces.
3.16.3 Low-power universal asynchronous receiver transmitter (LPUART)
The devices embed one Low-power UART. The LPUART supports asynchronous serial
communication with minimum power consumption. It supports half duplex single wire
communication and modem operations (CTS/RTS). It allows multiprocessor
communication.
The LPUART has a clock domain independent from the CPU clock. It can wake up the
system from Stop mode using baudrates up to 46 Kbaud. The Wakeup events from Stop
mode are programmable and can be:
Start bit detection
Or any received data frame
Or a specific programmed data frame
Table 12. USART implementation
USART modes/features(1)
1. X = supported.
USART1 and USART2
Hardware flow control for modem X
Continuous communication using DMA X
Multiprocessor communication X
Synchronous mode(2)
2. This mode allows using the USART as an SPI master.
X
Smartcard mode X
Single-wire half-duplex communication X
IrDA SIR ENDEC block X
LIN mode X
Dual clock domain and wakeup from Stop mode X
Receiver timeout interrupt X
Modbus communication X
Auto baud rate detection (4 modes) X
Driver Enable X
Functional overview STM32L051x6 STM32L051x8
32/132 DS10184 Rev 9
Only a 32.768 kHz clock (LSE) is needed to allow LPUART communication up to 9600
baud. Therefore, even in Stop mode, the LPUART can wait for an incoming frame while
having an extremely low energy consumption. Higher speed clock can be used to reach
higher baudrates.
LPUART interface can be served by the DMA controller.
3.16.4 Serial peripheral interface (SPI)/Inter-integrated sound (I2S)
Up to two SPIs are able to communicate at up to 16 Mbits/s in slave and master modes in
full-duplex and half-duplex communication modes. The 3-bit prescaler gives 8 master mode
frequencies and the frame is configurable to 8 bits or 16 bits. The hardware CRC
generation/verification supports basic SD Card/MMC modes.
The USARTs with synchronous capability can also be used as SPI master.
One standard I2S interfaces (multiplexed with SPI2) is available. It can operate in master or
slave mode, and can be configured to operate with a 16-/32-bit resolution as input or output
channels. Audio sampling frequencies from 8 kHz up to 192 kHz are supported. When the
I2S interfaces is configured in master mode, the master clock can be output to the external
DAC/CODEC at 256 times the sampling frequency.
The SPIs can be served by the DMA controller.
Refer to Table 13 for the differences between SPI1 and SPI2.
3.17 Cyclic redundancy check (CRC) calculation unit
The CRC (cyclic redundancy check) calculation unit is used to get a CRC code using a
configurable generator polynomial value and size.
Among other applications, CRC-based techniques are used to verify data transmission or
storage integrity. In the scope of the EN/IEC 60335-1 standard, they offer a means of
verifying the Flash memory integrity. The CRC calculation unit helps compute a signature of
the software during runtime, to be compared with a reference signature generated at
linktime and stored at a given memory location.
3.18 Serial wire debug port (SW-DP)
An Arm SW-DP interface is provided to allow a serial wire debugging tool to be connected to
the MCU.
Table 13. SPI/I2S implementation
SPI features(1)
1. X = supported.
SPI1 SPI2
Hardware CRC calculation X X
I2S mode - X
TI mode X X
DS10184 Rev 9 33/132
STM32L051x6 STM32L051x8 Pin descriptions
45
4 Pin descriptions
Figure 3. STM32L051x6/8 LQFP64 pinout - 10 x 10 mm
1. The above figure shows the package top view.
2. PA11 and PA12 input/output (greyed out pins) are supplied by VDDIO2.
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
17 18 19 20 21 22 23 24 29 30 31 3225 26 27 28
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
VDD
PC13
PC14-OSC32_IN
PC15-OSC32_OUT
PH0 -OSC_IN
PH1-OSC_OUT
NRST
PC0
PC1
PC2
PC3
VSSA
VDDA
PA0
PA1
PA2
VDD
VSS
PB9
PB8
BOOT0
PB7
PB6
PB5
PB4
PB3
PD2
PC12
PC11
PC10
PA15
PA14
VDDIO2
VSS
PA13
PA12
PA11
PA10
PA9
PA8
PC9
PC8
PC7
PC6
PB15
PB14
PB13
PB12
PA3
VSS
VDD
PA4
PA5
PA6
PA7
PC4
PC5
PB0
PB1
PB2
PB10
PB11
VSS
VDD
LQFP64
MS34741V2
Pin descriptions STM32L051x6 STM32L051x8
34/132 DS10184 Rev 9
Figure 4. STM32L051x6/8 TFBGA64 ballout - 5x 5 mm
1. The above figure shows the package top view.
2. PA11 and PA12 input/output (greyed out pins) are supplied by VDDIO2.
MSv34743V5
PH0-
OSC_IN
PC14-
OSC32_
IN
PC15-
OSC32_
OUT
PH1-
OSC_O
UT
A
B
C
D
E
F
G
H
8
23 4 5 6 7
1
NRST
VSSA
VREF+
VDDA
PC13
VDD
VSS
VDD
PC1
PC2
PA0
PA1
PB9 PB4 PB3 PA15 PA14 PA13
PB8 BOOT0 PD2 PC11 PC10 PA12
PB7 PB5 PC12 PA10 PA9 PA11
PB6 VSS VSS VSS PA8 PC9
PC0 VDD VDD VDD
IO2 PC7 PC8
PA2 PA 5 PB0 PC6 PB15 PB14
PA3 PA 6 PB1 PB2 PB10 PB13
PA4 PA7 PC4 PC5 PB11 PB12
DS10184 Rev 9 35/132
STM32L051x6 STM32L051x8 Pin descriptions
45
Figure 5. STM32L051x6/8 LQFP48 pinout - 7 x 7 mm
1. The above figure shows the package top view.
2. PA11 and PA12 input/output (greyed out pins) are supplied by VDDIO2.
Figure 6. STM32L051x6/8 WLCSP36 ballout
1. The above figure shows the package top view.
44 43 42 41 40 39 38 37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
12
13 14 15 16 17 18 19 20 21 22
1
2
3
4
5
6
7
8
9
10
11
48 47 46 45
PA3
PA4
PA5
PA6
PA7
PB0
PB1
PB2
PB10
PB11
VSS
VDD
VDDIO2
VSS
PA13
PA12
PA11
PA10
PA9
PA8
PB15
PB14
PB13
PB12
VDD
PC13
PC14-OSC32_IN
PC15-OSC32_OUT
PH0-OSC_IN
PH1-OSC_OUT
NRST
VSSA
VDDA
PA0
PA1
PA2
VDD
VSS
PB9
PB8
BOOT0
PB7
PB6
PB5
PB4
PB3
PA15
PA14
LQFP48
MS34745V2
PA10
PA13
MSv37853V1
A
B
C
D
E
F
12345
6
PA12
PA9
PA8
VDD
PA15
PA14
PA11
PB11
PB10
PB2
PB4 PB7 VDD
PC14-
OSC32
_IN
PB3 PB6 PB8 PC15-
OSC32
_OUT
PB1 PB5 BOO
T0 NRST
PB0 PA0 VDDA VSS
PA6 PA4 PA2 VREF
+
PA7 PA5 PA3 PA1
Pin descriptions STM32L051x6 STM32L051x8
36/132 DS10184 Rev 9
Figure 7. STM32L051x6/8 LQFP32 pinout
1. The above figure shows the package top view.
Figure 8. STM32L051x6/8 UFQFPN32 pinout
1. The above figure shows the package top view.
MSv35429V3
32 31 30 29 28 27 26 25
24
23
22
20
19
18
17
891011121
314 15 16
1
2
3
4
5
6
7
PA3
PA4
PA5
PA6
PA7
PB0
PB1
VSS
PA14
PA13
PA12
PA11
PA10
PA9
PA8
VDD
NRST
VDDA
PA0
PA1
PA2
VSS
BOOT0
PB7
PB6
PB5
PB4
PB3
PA15
PC14-OSC32_IN
PC15-OSC32_OUT
VDD
21
LQFP32
MSv37854V2
32 31 30 29 28 27 26 25
24
23
22
20
19
18
17
891011121314 15 16
1
2
3
4
5
6
7
PA3
PA4
PA5
PA6
PA7
PB0
PB1
PB2
PA14
PA13
PA12
PA11
PA10
PA9
PA8
VDD
NRST
VDDA
PA0
PA1
PA2
PB8
BOOT0
PB7
PB6
PB5
PB4
PB3
PA15
PC14-OSC32_IN
PC15-OSC32_OUT
VDD
21
VSS
DS10184 Rev 9 37/132
STM32L051x6 STM32L051x8 Pin descriptions
45
Table 14. Legend/abbreviations used in the pinout table
Name Abbreviation Definition
Pin name Unless otherwise specified in brackets below the pin name, the pin function during
and after reset is the same as the actual pin name
Pin type
S Supply pin
I Input only pin
I/O Input / output pin
I/O structure
FT 5 V tolerant I/O
FTf 5 V tolerant I/O, FM+ capable
TC Standard 3.3V I/O
B Dedicated BOOT0 pin
RST Bidirectional reset pin with embedded weak pull-up resistor
Notes Unless otherwise specified by a note, all I/Os are set as floating inputs during and
after reset.
Pin functions
Alternate
functions Functions selected through GPIOx_AFR registers
Additional
functions Functions directly selected/enabled through peripheral registers
Table 15. STM32L051x6/8 pin definitions
Pin Number
Pin name
(function
after reset)
Pin type
I/O structure
Notes
Alternate functions Additional
functions
LQFP64
TFBGA64
LQFP48
WLCSP36(1)
LQFP32
UFQFPN32
1B21 - - - VDD S -- - -
2A22 - - - PC13 I/OFT- -
RTC_TAMP1/
RTC_TS/
RTC_OUT/
WKUP2
3A13A62 2
PC14-
OSC32_IN
(PC14)
I/O FT - - OSC32_IN
4B14B63 3
PC15-
OSC32_OUT
(PC15)
I/O TC - - OSC32_OUT
Pin descriptions STM32L051x6 STM32L051x8
38/132 DS10184 Rev 9
5C15 - - -
PH0-OSC_IN
(PH0) I/O TC - - OSC_IN
6D16 - - -
PH1-
OSC_OUT
(PH1)
I/O TC - - OSC_OUT
7 E1 7 C6 4 4 NRST I/O RST - - -
8E3- - - - PC0 I/OFT- LPTIM1_IN1,
EVENTOUT ADC_IN10
9E2- - - - PC1 I/OFT- LPTIM1_OUT,
EVENTOUT ADC_IN11
10 F2 - - - - PC2 I/O FT -
LPTIM1_IN2,
SPI2_MISO/I2S2_M
CK
ADC_IN12
11----- PC3 I/OFT- LPTIM1_ETR,
SPI2_MOSI/I2S2_SD ADC_IN13
12 F1 8 - - - VSSA S - - -
- G1 - E6 - - VREF+ S - - -
13 H1 9 D5 5 5 VDDA S - - -
14 G2 10 D4 6 6 PA0 I/O TC -
TIM2_CH1,
USART2_CTS,
TIM2_ETR,
COMP1_OUT
COMP1_INM6,
ADC_IN0,
RTC_TAMP2/WKU
P1
15 H2 11 F6 7 7 PA1 I/O FT -
EVENTOUT,
TIM2_CH2,
USART2_RTS/
USART2_DE,
TIM21_ETR
COMP1_INP,
ADC_IN1
16 F3 12 E5 8 8 PA2 I/O FT -
TIM21_CH1,
TIM2_CH3,
USART2_TX,
COMP2_OUT
COMP2_INM6,
ADC_IN2
17 G3 13 F5 9 9 PA3 I/O FT -
TIM21_CH2,
TIM2_CH4,
USART2_RX
COMP2_INP,
ADC_IN3
Table 15. STM32L051x6/8 pin definitions (continued)
Pin Number
Pin name
(function
after reset)
Pin type
I/O structure
Notes
Alternate functions Additional
functions
LQFP64
TFBGA64
LQFP48
WLCSP36(1)
LQFP32
UFQFPN32
DS10184 Rev 9 39/132
STM32L051x6 STM32L051x8 Pin descriptions
45
18 C2 - - - - VSS S - - -
19 D2 - - - - VDD S - - -
20 H3 14 E4 10 10 PA4 I/O TC
SPI1_NSS,
USART2_CK,
TIM22_ETR
COMP1_INM4,
COMP2_INM4,
ADC_IN4
21 F4 15 F4 11 11 PA5 I/O TC -
SPI1_SCK,
TIM2_ETR,
TIM2_CH1
COMP1_INM5,
COMP2_INM5,
ADC_IN5
22 G4 16 E3 12 12 PA6 I/O FT -
SPI1_MISO,
LPUART1_CTS,
TIM22_CH1,
EVENTOUT,
COMP1_OUT
ADC_IN6
23 H4 17 F3 13 13 PA7 I/O FT -
SPI1_MOSI,
TIM22_CH2,
EVENTOUT,
COMP2_OUT
ADC_IN7
24 H5 - - - - PC4 I/O FT - EVENTOUT,
LPUART1_TX ADC_IN14
25 H6 - - - - PC5 I/O FT - LPUART1_RX, ADC_IN15
26 F5 18 D3 14 14 PB0 I/O FT - EVENTOUT ADC_IN8,
VREF_OUT
27 G5 19 C3 15 15 PB1 I/O FT - LPUART1_RTS/
LPUART1_DE
ADC_IN9,
VREF_OUT
28 G6 20 F2 - 16 PB2 I/O FT - LPTIM1_OUT -
29 G7 21 E2 - - PB10 I/O FT -
TIM2_CH3,
LPUART1_TX,
SPI2_SCK,
I2C2_SCL
-
30 H7 22 D2 - - PB11 I/O FT -
EVENTOUT,
TIM2_CH4,
LPUART1_RX,
I2C2_SDA
-
31 D6 23 - 16 - VSS S - - - -
Table 15. STM32L051x6/8 pin definitions (continued)
Pin Number
Pin name
(function
after reset)
Pin type
I/O structure
Notes
Alternate functions Additional
functions
LQFP64
TFBGA64
LQFP48
WLCSP36(1)
LQFP32
UFQFPN32
Pin descriptions STM32L051x6 STM32L051x8
40/132 DS10184 Rev 9
32 E6 24 F1 17 17 VDDIO2 S - - - -
33 H8 25 - - - PB12 I/O FT -
SPI2_NSS/I2S2_WS,
LPUART1_RTS/
LPUART1_DE,
EVENTOUT
-
34 G8 26 - - - PB13 I/O FTf -
SPI2_SCK/I2S2_CK,
LPUART1_CTS,
I2C2_SCL,
TIM21_CH1
-
35 F8 27 - - - PB14 I/O FTf -
SPI2_MISO/I
2S2_MCK,
RTC_OUT,
LPUART1_RTS/
LPUART1_DE,
I2C2_SDA,
TIM21_CH2
-
36 F7 28 - - - PB15 I/O FT - SPI2_MOSI/I2S2_SD
, RTC_REFIN -
37 F6 - - - - PC6 I/O FT - TIM22_CH1 -
38 E7 - - - - PC7 I/O FT - TIM22_CH2 -
39 E8 - - - - PC8 I/O FT - TIM22_ETR -
40 D8 - - - - PC9 I/O FT - TIM21_ETR -
41 D7 29 E1 18 18 PA8 I/O FT - MCO, EVENTOUT,
USART1_CK -
42 C7 30 D1 19 19 PA9 I/O FT - MCO, USART1_TX -
43 C6 31 C1 20 20 PA10 I/O FT - USART1_RX -
44 C8 32 C2 21 21 PA11 I/O FT -
SPI1_MISO,
EVENTOUT,
USART1_CTS,
COMP1_OUT
-
Table 15. STM32L051x6/8 pin definitions (continued)
Pin Number
Pin name
(function
after reset)
Pin type
I/O structure
Notes
Alternate functions Additional
functions
LQFP64
TFBGA64
LQFP48
WLCSP36(1)
LQFP32
UFQFPN32
DS10184 Rev 9 41/132
STM32L051x6 STM32L051x8 Pin descriptions
45
45 B8 33 B1 22 22 PA12 I/O FT -
SPI1_MOSI,
EVENTOUT,
USART1_RTS/
USART1_DE,
COMP2_OUT
-
46 A8 34 A1 23 23 PA13 I/O FT - SWDIO -
47 D5 35 - - - VSS S - - -
48 E5 36 - - - VDD S - - -
49 A7 37 B2 24 24 PA14 I/O FT - SWCLK,
USART2_TX
50 A6 38 A2 25 25 PA15 I/O FT -
SPI1_NSS,
TIM2_ETR,
EVENTOUT,
USART2_RX,
TIM2_CH1
-
51 B7 - - - - PC10 I/O FT - LPUART1_TX -
52 B6 - - - - PC11 I/O FT - LPUART1_RX -
53 C5 - - - - PC12 I/O FT - - -
54 B5 - - - - PD2 I/O FT - LPUART1_RTS/
LPUART1_DE -
55 A5 39 B3 26 26 PB3 I/O FT -
SPI1_SCK,
TIM2_CH2,
EVENTOUT
COMP2_INN
56 A4 40 A3 27 27 PB4 I/O FT -
SPI1_MISO,
EVENTOUT,
TIM22_CH1
COMP2_INP
57 C4 41 C4 28 28 PB5 I/O FT -
SPI1_MOSI,
LPTIM1_IN1,
I2C1_SMBA,
TIM22_CH2
COMP2_INP
58 D3 42 B4 29 29 PB6 I/O FTf -
USART1_TX,
I2C1_SCL,
LPTIM1_ETR
COMP2_INP
Table 15. STM32L051x6/8 pin definitions (continued)
Pin Number
Pin name
(function
after reset)
Pin type
I/O structure
Notes
Alternate functions Additional
functions
LQFP64
TFBGA64
LQFP48
WLCSP36(1)
LQFP32
UFQFPN32
Pin descriptions STM32L051x6 STM32L051x8
42/132 DS10184 Rev 9
59 C3 43 A4 30 30 PB7 I/O FTf -
USART1_RX,
I2C1_SDA,
LPTIM1_IN2
COMP2_INP,
PVD_IN
60 B4 44 C5 31 31 BOOT0 B - - -
61 B3 45 B5 - 32 PB8 I/O FTf - I2C1_SCL -
62 A3 46 - - - PB9 I/O FTf -
EVENTOUT,
I2C1_SDA,
SPI2_NSS/I2S2_WS
-
63 D4 47 D6 32 - VSS S - - - -
64 E4 48 A5 1 1 VDD S - - - -
1. PB9/12/13/14/15, PH0/1 and PC13 GPIOs should be configured as output and driven Low, even if they are not available on
this package.
Table 15. STM32L051x6/8 pin definitions (continued)
Pin Number
Pin name
(function
after reset)
Pin type
I/O structure
Notes
Alternate functions Additional
functions
LQFP64
TFBGA64
LQFP48
WLCSP36(1)
LQFP32
UFQFPN32
STM32L051x6 STM32L051x8 Pin descriptions
DS10184 Rev 9 43/132
Table 16. Alternate function port A
Port
AF0 AF1 AF2 AF3 AF4 AF5 AF6 AF7
SPI1/TIM21/SYS_A
F/EVENTOUT/ -TIM2/
EVENTOUT/ EVENTOUT USART1/2/3 TIM2/21/22 EVENTOUT COMP1/2
Port A
PA0 - - TIM2_CH1 - USART2_CTS TIM2_ETR - COMP1_OUT
PA1 EVENTOUT - TIM2_CH2 - USART2_RTS/
USART2_DE TIM21_ETR - -
PA2 TIM21_CH1 - TIM2_CH3 - USART2_TX - - COMP2_OUT
PA3 TIM21_CH2 - TIM2_CH4 - USART2_RX - - -
PA4 SPI1_NSS - - - USART2_CK TIM22_ETR - -
PA5 SPI1_SCK - TIM2_ETR - - TIM2_CH1 - -
PA6 SPI1_MISO - - - LPUART1_CTS TIM22_CH1 EVENTOUT COMP1_OUT
PA7 SPI1_MOSI - - - - TIM22_CH2 EVENTOUT COMP2_OUT
PA8 MCO - - EVENTOUT USART1_CK - - -
PA9 MCO - - - USART1_TX - - -
PA10 - - - - USART1_RX - - -
PA11 SPI1_MISO - EVENTOUT - USART1_CTS - - COMP1_OUT
PA12 SPI1_MOSI - EVENTOUT - USART1_RTS/
USART1_DE - - COMP2_OUT
PA13 SWDIO - - - - - - -
PA14 SWCLK - - - USART2_TX - - -
PA15 SPI1_NSS - TIM2_ETR EVENTOUT USART2_RX TIM2_CH1 - -
Pin descriptions STM32L051x6 STM32L051x8
44/132 DS10184 Rev 9
Table 17. Alternate function port B
Port
AF0 AF1 AF2 AF3 AF4 AF5 AF6
SPI1/SPI2/I2S2/
USART1/
EVENTOUT/
I2C1
LPUART1/LPTIM
/TIM2/SYS_AF/
EVENTOUT
I2C1
I2C1/TIM22/
EVENTOUT/
LPUART1
SPI2/I2S2/I2C2 I2C2/TIM21/
EVENTOUT
Port B
PB0 EVENTOUT - - - - - -
PB1 - - - - LPUART1_RTS/
LPUART1_DE --
PB2 - - LPTIM1_OUT - - - -
PB3 SPI1_SCK - TIM2_CH2 - EVENTOUT - -
PB4 SPI1_MISO - EVENTOUT - TIM22_CH1 - -
PB5 SPI1_MOSI - LPTIM1_IN1 I2C1_SMBA TIM22_CH2 - -
PB6 USART1_TX I2C1_SCL LPTIM1_ETR - - - -
PB7 USART1_RX I2C1_SDA LPTIM1_IN2 - - - -
PB8 - - - - I2C1_SCL - -
PB9 - - EVENTOUT - I2C1_SDA SPI2_NSS/I2S2_
WS -
PB10 - - TIM2_CH3 - LPUART1_TX SPI2_SCK I2C2_SCL
PB11 EVENTOUT - TIM2_CH4 - LPUART1_RX - I2C2_SDA
PB12 SPI2_NSS/I2S2_WS - LPUART1_RTS/
LPUART1_DE - - - EVENTOUT
PB13 SPI2_SCK/I2S2_CK - - - LPUART1_CTS I2C2_SCL TIM21_CH1
PB14 SPI2_MISO/I2S2_MCK - RTC_OUT - LPUART1_RTS/
LPUART1_DE I2C2_SDA TIM21_CH2
PB15 SPI2_MOSI/I2S2_SD - RTC_REFIN - - -
STM32L051x6 STM32L051x8 Pin descriptions
DS10184 Rev 9 45/132
Table 18. Alternate function port C
Port
AF0 AF1 AF2
LPUART1/LPTIM/TIM21/12/EVENTOUT - SPI2/I2S2/LPUART1/EVENTOUT
Port C
PC0 LPTIM1_IN1 - EVENTOUT
PC1 LPTIM1_OUT - EVENTOUT
PC2 LPTIM1_IN2 - SPI2_MISO/I2S2_MCK
PC3 LPTIM1_ETR - SPI2_MOSI/I2S2_SD
PC4 EVENTOUT - LPUART1_TX
PC5 - LPUART1_RX
PC6 TIM22_CH1 - -
PC7 TIM22_CH2 - -
PC8 TIM22_ETR - -
PC9 TIM21_ETR - -
PC10 LPUART1_TX - -
PC11 LPUART1_RX - -
PC12 - - -
PC13 - - -
PC14 - - -
PC15 - - -
Table 19. Alternate function port D
Port
AF0 AF1
LPUART1 -
Port D PD2 LPUART1_RTS/LPUART1_DE -
Memory mapping STM32L051x6 STM32L051x8
46/132 DS10184 Rev 9
5 Memory mapping
Refer to the product line reference manual for details on the memory mapping as well as the
boundary addresses for all peripherals.
DS10184 Rev 9 47/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
6 Electrical characteristics
6.1 Parameter conditions
Unless otherwise specified, all voltages are referenced to VSS.
6.1.1 Minimum and maximum values
Unless otherwise specified the minimum and maximum values are guaranteed in the worst
conditions of ambient temperature, supply voltage and frequencies by tests in production on
100% of the devices with an ambient temperature at TA = 25 °C and TA = TAmax (given by
the selected temperature range).
Data based on characterization results, design simulation and/or technology characteristics
are indicated in the table footnotes and are not tested in production. Based on
characterization, the minimum and maximum values refer to sample tests and represent the
mean value plus or minus three times the standard deviation (mean±3σ).
6.1.2 Typical values
Unless otherwise specified, typical data are based on TA = 25 °C, VDD = 3.6 V (for the
1.65 V VDD 3.6 V voltage range). They are given only as design guidelines and are not
tested.
Typical ADC accuracy values are determined by characterization of a batch of samples from
a standard diffusion lot over the full temperature range, where 95% of the devices have an
error less than or equal to the value indicated (mean±2σ).
6.1.3 Typical curves
Unless otherwise specified, all typical curves are given only as design guidelines and are
not tested.
6.1.4 Loading capacitor
The loading conditions used for pin parameter measurement are shown in Figure 9.
6.1.5 Pin input voltage
The input voltage measurement on a pin of the device is described in Figure 10.
Figure 9. Pin loading conditions Figure 10. Pin input voltage
Electrical characteristics STM32L051x6 STM32L051x8
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6.1.6 Power supply scheme
Figure 11. Power supply scheme
6.1.7 Current consumption measurement
Figure 12. Current consumption measurement scheme
MSv34740V1
Analog:
RC,PLL,COMP,
….
VDD
GP I/Os
OUT
IN Kernel logic
(CPU,
Digital &
Memories)
Standby-power circuitry
(OSC32,RTC,Wake-up
logic, RTC backup
registers)
N × 100 nF
+ 1 × 10 μF
Regulator
VSS
VDDA
VREF+
VREF-
VSSA
ADC
Level shifter
IO
Logic
VDD
100 nF
+ 1 μF
VREF
100 nF
+ 1 μF
VDDA
MSv34711V1
NxVDD
IDD
N × 100 nF
+ 1 × 10 μF NxVSS
VDDA
DS10184 Rev 9 49/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
6.2 Absolute maximum ratings
Stresses above the absolute maximum ratings listed in Table 20: Voltage characteristics,
Table 21: Current characteristics, and Table 22: Thermal characteristics may cause
permanent damage to the device. These are stress ratings only and functional operation of
the device at these conditions is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability. Device mission profile (application conditions)
is compliant with JEDEC JESD47 Qualification Standard. Extended mission profiles are
available on demand.
Table 20. Voltage characteristics
Symbol Definition Min Max Unit
VDD–VSS
External main supply voltage
(including VDDA, VDDIO2, VDD)(1)
1. All main power (VDD,VDDIO2, VDDA) and ground (VSS, VSSA) pins must always be connected to the external
power supply, in the permitted range.
–0.3 4.0
V
VIN(2)
2. VIN maximum must always be respected. Refer to Table 21 for maximum allowed injected current values.
Input voltage on FT and FTf pins VSS 0.3 VDD+4.0
Input voltage on TC pins VSS 0.3 4.0
Input voltage on BOOT0 VSS VDD + 4.0
Input voltage on any other pin VSS 0.3 4.0
|ΔVDD| Variations between different VDDx power pins - 50
mV|VDDA-VDDx|Variations between any VDDx and VDDA power
pins(3)
3. It is recommended to power VDD and VDDA from the same source. A maximum difference of 300 mV
between VDD and VDDA can be tolerated during power-up and device operation. VDDIO2 is independent
from VDD and VDDA: its value does not need to respect this rule.
- 300
|ΔVSS| Variations between all different ground pins - 50
VREF+ –VDDA Allowed voltage difference for VREF+ > VDDA -0.4V
VESD(HBM)
Electrostatic discharge voltage
(human body model) see Section 6.3.11
Electrical characteristics STM32L051x6 STM32L051x8
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Table 21. Current characteristics
Symbol Ratings Max. Unit
ΣIVDD(2) Total current into sum of all VDD power lines (source)(1)
1. All main power (VDD, VDDA) and ground (VSS, VSSA) pins must always be connected to the external power
supply, in the permitted range.
105
mA
ΣIVSS(2)
2. This current consumption must be correctly distributed over all I/Os and control pins. The total output
current must not be sunk/sourced between two consecutive power supply pins referring to high pin count
LQFP packages.
Total current out of sum of all VSS ground lines (sink)(1) 105
ΣIVDDIO2 Total current into VDDIO2 power line (source) 25
IVDD(PIN) Maximum current into each VDD power pin (source)(1) 100
IVSS(PIN) Maximum current out of each VSS ground pin (sink)(1) 100
IIO
Output current sunk by any I/O and control pin except FTf
pins 16
Output current sunk by FTf pins 22
Output current sourced by any I/O and control pin -16
ΣIIO(PIN)
Total output current sunk by sum of all IOs and control pins
except PA11 and PA12(2) 90
Total output current sunk by PA11 and PA12 25
Total output current sourced by sum of all IOs and control
pins(2) -90
IINJ(PIN)
Injected current on FT, FTf, RST and B pins -5/+0(3)
3. Positive current injection is not possible on these I/Os. A negative injection is induced by VIN<VSS. IINJ(PIN)
must never be exceeded. Refer to Table 20 for maximum allowed input voltage values.
Injected current on TC pin ± 5(4)
4. A positive injection is induced by VIN > VDD while a negative injection is induced by VIN < VSS. IINJ(PIN)
must never be exceeded. Refer to Table 20: Voltage characteristics for the maximum allowed input voltage
values.
ΣIINJ(PIN) Total injected current (sum of all I/O and control pins)(5)
5. When several inputs are submitted to a current injection, the maximum ΣIINJ(PIN) is the absolute sum of the
positive and negative injected currents (instantaneous values).
± 25
Table 22. Thermal characteristics
Symbol Ratings Value Unit
TSTG Storage temperature range –65 to +150 °C
TJMaximum junction temperature 150 °C
DS10184 Rev 9 51/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
6.3 Operating conditions
6.3.1 General operating conditions
Table 23. General operating conditions
Symbol Parameter Conditions Min Max Unit
fHCLK Internal AHB clock frequency - 0 32
MHzfPCLK1 Internal APB1 clock frequency - 0 32
fPCLK2 Internal APB2 clock frequency - 0 32
VDD Standard operating voltage
BOR detector disabled 1.65 3.6
VBOR detector enabled, at power-on 1.8 3.6
BOR detector disabled, after power-on 1.65 3.6
VDDA
Analog operating voltage (all
features) Must be the same voltage as VDD(1) 1.65 3.6 V
VDDIO2 Standard operating voltage - 1.65 3.6 V
VIN
Input voltage on FT, FTf and RST
pins(2)
2.0 V VDD 3.6 V -0.3 5.5
V
1.65 V VDD 2.0 V -0.3 5.2
Input voltage on BOOT0 pin - 0 5.5
Input voltage on TC pin - -0.3 VDD+0.3
PD
Power dissipation at TA = 85 °C
(range 6) or TA =105 °C (rage 7) (3)
TFBGA64 package - 327
mW
LQFP64 package - 444
LQFP48 package - 363
Standard WLCSP36 package - 318
Thin WLCSP36 package - 338
LQFP32 package - 351
UFQFPN32 - 526
Power dissipation at TA = 125 °C
(range 3) (3)
TFBGA64 package - 81
LQFP64 package - 111
LQFP48 package - 91
Standard WLCSP36 package - 79
Thin WLCSP36 package - 84
LQFP32 package - 88
UFQFPN32 - 132
Electrical characteristics STM32L051x6 STM32L051x8
52/132 DS10184 Rev 9
TA Temperature range
Maximum power dissipation (range 6) –40 85
°C
Maximum power dissipation (range 7) –40 105
Maximum power dissipation (range 3) –40 125
TJ
Junction temperature range (range 6) -40 °C TA 85 ° –40 105
Junction temperature range (range 7) -40 °C TA 105 °C –40 125
Junction temperature range (range 3) -40 °C TA 125 °C –40 130
1. It is recommended to power VDD and VDDA from the same source. A maximum difference of 300 mV between VDD and VDDA
can be tolerated during power-up and normal operation.
2. To sustain a voltage higher than VDD+0.3V, the internal pull-up/pull-down resistors must be disabled.
3. If TA is lower, higher PD values are allowed as long as TJ does not exceed TJ max (see Table 22: Thermal characteristics on
page 50).
Table 23. General operating conditions (continued)
Symbol Parameter Conditions Min Max Unit
DS10184 Rev 9 53/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
6.3.2 Embedded reset and power control block characteristics
The parameters given in the following table are derived from the tests performed under the
ambient temperature condition summarized in Table 23.
Table 24. Embedded reset and power control block characteristics
Symbol Parameter Conditions Min Typ Max Unit
tVDD(1)
VDD rise time rate
BOR detector enabled 0 -
µs/V
BOR detector disabled 0 - 1000
VDD fall time rate
BOR detector enabled 20 -
BOR detector disabled 0 - 1000
TRSTTEMPO(1) Reset temporization
VDD rising, BOR enabled - 2 3.3
ms
VDD rising, BOR disabled(2) 0.4 0.7 1.6
VPOR/PDR
Power-on/power down reset
threshold
Falling edge 1 1.5 1.65
V
Rising edge 1.3 1.5 1.65
VBOR0 Brown-out reset threshold 0
Falling edge 1.67 1.7 1.74
Rising edge 1.69 1.76 1.8
VBOR1 Brown-out reset threshold 1
Falling edge 1.87 1.93 1.97
Rising edge 1.96 2.03 2.07
VBOR2 Brown-out reset threshold 2
Falling edge 2.22 2.30 2.35
Rising edge 2.31 2.41 2.44
VBOR3 Brown-out reset threshold 3
Falling edge 2.45 2.55 2.6
Rising edge 2.54 2.66 2.7
VBOR4 Brown-out reset threshold 4
Falling edge 2.68 2.8 2.85
Rising edge 2.78 2.9 2.95
VPVD0
Programmable voltage detector
threshold 0
Falling edge 1.8 1.85 1.88
Rising edge 1.88 1.94 1.99
VPVD1 PVD threshold 1
Falling edge 1.98 2.04 2.09
Rising edge 2.08 2.14 2.18
VPVD2 PVD threshold 2
Falling edge 2.20 2.24 2.28
Rising edge 2.28 2.34 2.38
VPVD3 PVD threshold 3
Falling edge 2.39 2.44 2.48
Rising edge 2.47 2.54 2.58
VPVD4 PVD threshold 4
Falling edge 2.57 2.64 2.69
Rising edge 2.68 2.74 2.79
VPVD5 PVD threshold 5
Falling edge 2.77 2.83 2.88
Rising edge 2.87 2.94 2.99
Electrical characteristics STM32L051x6 STM32L051x8
54/132 DS10184 Rev 9
6.3.3 Embedded internal reference voltage
The parameters given in Table 26 are based on characterization results, unless otherwise
specified.
VPVD6 PVD threshold 6
Falling edge 2.97 3.05 3.09
V
Rising edge 3.08 3.15 3.20
Vhyst Hysteresis voltage
BOR0 threshold - 40 -
mV
All BOR and PVD thresholds
excepting BOR0 -100-
1. Guaranteed by characterization results.
2. Valid for device version without BOR at power up. Please see option "D" in Ordering information scheme for more details.
Table 24. Embedded reset and power control block characteristics (continued)
Symbol Parameter Conditions Min Typ Max Unit
Table 25. Embedded internal reference voltage calibration values
Calibration value name Description Memory address
VREFINT_CAL
Raw data acquired at
temperature of 25 °C
VDDA= 3 V
0x1FF8 0078 - 0x1FF8 0079
Table 26. Embedded internal reference voltage(1)
Symbol Parameter Conditions Min Typ Max Unit
VREFINT out(2) Internal reference voltage – 40 °C < TJ < +125 °C 1.202 1.224 1.242 V
TVREFINT Internal reference startup time - - 2 3 ms
VVREF_MEAS
VDDA and VREF+ voltage during
VREFINT factory measure -2.9933.01V
AVREF_MEAS
Accuracy of factory-measured
VREFINT value(3)
Including uncertainties
due to ADC and
VDDA/VREF+ values
-- ±5mV
TCoeff(4) Temperature coefficient –40 °C < TJ < +125 °C - 25 100 ppm/°C
ACoeff(4) Long-term stability 1000 hours, T= 25 °C - - 1000 ppm
VDDCoeff(4) Voltage coefficient 3.0 V < VDDA < 3.6 V - - 2000 ppm/V
TS_vrefint(4)(5)
ADC sampling time when
reading the internal reference
voltage
-510-µs
TADC_BUF(4) Startup time of reference
voltage buffer for ADC ---10µs
IBUF_ADC(4) Consumption of reference
voltage buffer for ADC - - 13.5 25 µA
IVREF_OUT(4) VREF_OUT output current(6) ---1µA
CVREF_OUT(4) VREF_OUT output load - - - 50 pF
DS10184 Rev 9 55/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
6.3.4 Supply current characteristics
The current consumption is a function of several parameters and factors such as the
operating voltage, temperature, I/O pin loading, device software configuration, operating
frequencies, I/O pin switching rate, program location in memory and executed binary code.
The current consumption is measured as described in Figure 12: Current consumption
measurement scheme.
All Run-mode current consumption measurements given in this section are performed with a
reduced code that gives a consumption equivalent to Dhrystone 2.1 code if not specified
otherwise.
The current consumption values are derived from the tests performed under ambient
temperature and VDD supply voltage conditions summarized in Table 23: General operating
conditions unless otherwise specified.
The MCU is placed under the following conditions:
All I/O pins are configured in analog input mode
All peripherals are disabled except when explicitly mentioned
The Flash memory access time and prefetch is adjusted depending on fHCLK
frequency and voltage range to provide the best CPU performance unless otherwise
specified.
When the peripherals are enabled fAPB1 = fAPB2 = fAPB
When PLL is ON, the PLL inputs are equal to HSI = 16 MHz (if internal clock is used) or
HSE = 16 MHz (if HSE bypass mode is used)
The HSE user clock applied to OSCI_IN input follows the characteristic specified in
Table 40: High-speed external user clock characteristics
For maximum current consumption VDD = VDDA = 3.6 V is applied to all supply pins
For typical current consumption VDD = VDDA = 3.0 V is applied to all supply pins if not
specified otherwise
The parameters given in Table 47, Table 23 and Table 24 are derived from tests performed
under ambient temperature and VDD supply voltage conditions summarized in Table 23.
ILPBUF(4)
Consumption of reference
voltage buffer for VREF_OUT
and COMP
- - 730 1200 nA
VREFINT_DIV1(4) 1/4 reference voltage - 24 25 26
%
VREFINT
VREFINT_DIV2(4) 1/2 reference voltage - 49 50 51
VREFINT_DIV3(4) 3/4 reference voltage - 74 75 76
1. Refer to Table 38: Peripheral current consumption in Stop and Standby mode for the value of the internal reference current
consumption (IREFINT).
2. Guaranteed by test in production.
3. The internal VREF value is individually measured in production and stored in dedicated EEPROM bytes.
4. Guaranteed by design.
5. Shortest sampling time can be determined in the application by multiple iterations.
6. To guarantee less than 1% VREF_OUT deviation.
Table 26. Embedded internal reference voltage(1) (continued)
Symbol Parameter Conditions Min Typ Max Unit
Electrical characteristics STM32L051x6 STM32L051x8
56/132 DS10184 Rev 9
Table 27. Current consumption in Run mode, code with data processing running from Flash
Symbol Parameter Conditions fHCLK Typ Max(1) Unit
IDD
(Run
from
Flash)
Supply
current in
Run mode,
code
executed
from Flash
fHSE = fHCLK up to
16 MHz included,
fHSE = fHCLK/2 above
16 MHz (PLL ON)(2)
Range 3, VCORE=1.2 V
VOS[1:0]=11
1 MHz 165 230
µA2 MHz 290 360
4 MHz 555 630
Range 2, VCORE=1.5 V,
VOS[1:0]=10,
4 MHz 0.665 0.74
mA
8 MHz 1.3 1.4
16 MHz 2.6 2.8
Range 1, VCORE=1.8 V,
VOS[1:0]=01
8 MHz 1.55 1.7
16 MHz 3.1 3.4
32 MHz 6.3 6.8
MSI clock Range 3, VCORE=1.2 V,
VOS[1:0]=11
65 kHz 36.5 110
µA524 kHz 99.5 190
4.2 MHz 620 700
HSI clock
Range 2, VCORE=1.5 V,
VOS[1:0]=10, 16 MHz 2.6 2.9
mA
Range 1, VCORE=1.8 V,
VOS[1:0]=01 32 MHz 6.25 7
1. Guaranteed by characterization results at 125 °C, unless otherwise specified.
2. Oscillator bypassed (HSEBYP = 1 in RCC_CR register).
Table 28. Current consumption in Run mode vs code type,
code with data processing running from Flash
Symbol Parameter Conditions fHCLK Typ Unit
IDD
(Run
from
Flash)
Supply
current in
Run mode,
code
executed
from Flash
fHSE = fHCLK up to
16 MHz included,
fHSE = fHCLK/2 above
16 MHz (PLL ON)(1)
Range 3,
VCORE=1.2 V,
VOS[1:0]=11
Dhrystone
4 MHz
555
µA
CoreMark 585
Fibonacci 440
while(1) 355
while(1), prefetch
OFF 353
Range 1,
VCORE=1.8 V,
VOS[1:0]=01
Dhrystone
32 MHz
6.3
mA
CoreMark 6.3
Fibonacci 6.55
while(1) 5.4
while(1), prefetch
OFF 5.2
1. Oscillator bypassed (HSEBYP = 1 in RCC_CR register).
DS10184 Rev 9 57/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
Figure 13. IDD vs VDD, at TA= 25/55/85/105 °C, Run mode, code running from
Flash memory, Range 2, HSE, 1WS
Figure 14. IDD vs VDD, at TA= 25/55/85/105 °C, Run mode, code running from
Flash memory, Range 2, HSI16, 1WS
MSv34792V1
Dhrystone 2.1 - 1 WS - 55°C
Dhrystone 2.1- 1 WS - 85°C
Dhrystone 2.1- 1 WS – 25°C
Dhrystone 2.1- 1 WS - 105°C
0
0.50
1.00
1.50
2.00
2.50
3.00
1.80E+00 2.00E+00 2.20E+00 2.40E+00 2.60E+00 2.80E+00 3.00E+00 3.20E+00 3.40E+00 3.60E+00
IDD (mA)
VDD (V)
MSv34793V1
IDD (mA)
VDD (V)
Dhrystone 2.1 - 1 WS - 55°C
Dhrystone 2.1- 1 WS - 85°C
Dhrystone 2.1- 1 WS – 25°C
Dhrystone 2.1- 1 WS - 105°C
0
0.50
1.00
1.50
2.00
2.50
3.00
1.80E+00 2.00E+00 2.20E+00 2.40E+00 2.60E+00 2.80E+00 3.00E+00 3.20E+00 3.40E+00 3.60E+00
Electrical characteristics STM32L051x6 STM32L051x8
58/132 DS10184 Rev 9
Table 29. Current consumption in Run mode, code with data processing running from RAM
Symbol Parameter Conditions fHCLK Typ Max(1) Unit
IDD (Run
from
RAM)
Supply current in
Run mode, code
executed from
RAM, Flash
switched off
fHSE = fHCLK up to 16
MHz included,
fHSE = fHCLK/2 above
16 MHz (PLL ON)(2)
Range 3,
VCORE=1.2 V,
VOS[1:0]=11
1 MHz 135 170
µA2 MHz 240 270
4 MHz 450 480
Range 2,
VCORE=1.5 ,V,
VOS[1:0]=10
4 MHz 0.52 0.6
mA
8 MHz 1 1.2
16 MHz 2 2.3
Range 1,
VCORE=1.8 V,
VOS[1:0]=01
8 MHz 1.25 1.4
16 MHz 2.45 2.8
32 MHz 5.1 5.4
MSI clock
Range 3,
VCORE=1.2 V,
VOS[1:0]=11
65 kHz 34.5 75
µA524 kHz 83 120
4.2 MHz 485 540
HSI16 clock source
(16 MHz)
Range 2,
VCORE=1.5 V,
VOS[1:0]=10
16 MHz 2.1 2.3
mA
Range 1,
VCORE=1.8 V,
VOS[1:0]=01
32 MHz 5.1 5.6
1. Guaranteed by characterization results at 125 °C, unless otherwise specified.
2. Oscillator bypassed (HSEBYP = 1 in RCC_CR register).
Table 30. Current consumption in Run mode vs code type,
code with data processing running from RAM(1)
Symbol Parameter Conditions fHCLK Typ Unit
IDD (Run
from
RAM)
Supply current in
Run mode, code
executed from
RAM, Flash
switched off
fHSE = fHCLK up to
16 MHz included,
fHSE = fHCLK/2 above
16 MHz (PLL ON)(2)
Range 3,
VCORE=1.2 V,
VOS[1:0]=11
Dhrystone
4 MHz
450
µA
CoreMark 575
Fibonacci 370
while(1) 340
Range 1,
VCORE=1.8 V,
VOS[1:0]=01
Dhrystone
32 MHz
5.1
mA
CoreMark 6.25
Fibonacci 4.4
while(1) 4.7
1. Guaranteed by characterization results, unless otherwise specified.
2. Oscillator bypassed (HSEBYP = 1 in RCC_CR register).
DS10184 Rev 9 59/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
Table 31. Current consumption in Sleep mode
Symbol Parameter Conditions fHCLK Typ Max(1) Unit
IDD (Sleep)
Supply current
in Sleep
mode, Flash
OFF
fHSE = fHCLK up to
16 MHz included,
fHSE = fHCLK/2 above
16 MHz (PLL ON)(2)
Range 3,
VCORE=1.2 V,
VOS[1:0]=11
1 MHz 43.5 90
µA
2 MHz 72 120
4 MHz 130 180
Range 2,
VCORE=1.5 V,
VOS[1:0]=10
4 MHz 160 210
8 MHz 305 370
16 MHz 590 710
Range 1,
VCORE=1.8 V,
VOS[1:0]=01
8 MHz 370 430
16 MHz 715 860
32 MHz 1650 1900
MSI clock
Range 3,
VCORE=1.2 V,
VOS[1:0]=11
65 kHz 18 65
524 kHz 31.5 75
4.2 MHz 140 210
HSI16 clock source
(16 MHz)
Range 2,
VCORE=1.5 V,
VOS[1:0]=10
16 MHz 665 830
Range 1,
VCORE=1.8 V,
VOS[1:0]=01
32 MHz 1750 2100
Supply current
in Sleep
mode, Flash
ON
fHSE = fHCLK up to
16 MHz included,
fHSE = fHCLK/2 above
16 MHz (PLL ON)(2)
Range 3,
VCORE=1.2 V,
VOS[1:0]=11
1 MHz 57.5 130
2 MHz 84 170
4 MHz 150 280
Range 2,
CORE=1.5 V,
VOS[1:0]=10
4 MHz 170 310
8 MHz 315 420
16 MHz 605 770
Range 1,
VCORE=1.8 V,
VOS[1:0]=01
8 MHz 380 460
16 MHz 730 950
32 MHz 1650 2400
MSI clock
Range 3,
VCORE=1.2 V,
VOS[1:0]=11
65 kHz 29.5 110
524 kHz 44.5 130
4.2 MHz 150 270
HSI16 clock source
(16 MHz)
Range 2,
VCORE=1.5 V,
VOS[1:0]=10
16 MHz 680 950
Range 1,
VCORE=1.8 V,
VOS[1:0]=01
32 MHz 1750 2100
1. Guaranteed by characterization results at 125 °C, unless otherwise specified.
Electrical characteristics STM32L051x6 STM32L051x8
60/132 DS10184 Rev 9
2. Oscillator bypassed (HSEBYP = 1 in RCC_CR register).
Table 32. Current consumption in Low-power run mode
Symbol Parameter Conditions Typ Max(1) Unit
IDD
(LP Run)
Supply
current in
Low-power
run mode
All peripherals
OFF, code
executed from
RAM, Flash
switched off,
VDD from 1.65
to 3.6 V
MSI clock = 65 kHz,
fHCLK = 32 kHz
TA = 40 to 25°C 8.5 10
µA
TA = 85 °C 11.5 48
TA = 105 °C 15.5 53
TA = 125 °C 27.5 130
MSI clock= 65 kHz,
fHCLK = 65 kHz
TA =-40 °C to 25 °C 10 15
TA = 85 °C 15.5 50
TA = 105 °C 19.5 54
TA = 125 °C 31.5 130
MSI clock= 131 kHz,
fHCLK = 131 kHz
TA = 40 to 25°C 20 25
TA = 55 °C 23 50
TA = 85 °C 25.5 55
TA = 105 °C 29.5 64
TA = 125 °C 40 140
All peripherals
OFF, code
executed from
Flash, VDD
from 1.65 V to
3.6 V
MSI clock= 65 kHz,
fHCLK = 32 kHz
TA = 40 to 25°C 22 28
TA = 85 °C 26 68
TA = 105 °C 31 75
TA = 125 °C 44 95
MSI clock = 65 kHz,
fHCLK = 65 kHz
TA = 40 to 25°C 27.5 33
TA = 85 °C 31.5 73
TA = 105 °C 36.5 80
TA = 125 °C 49 100
MSI clock =
131 kHz,
fHCLK = 131 kHz
TA = 40 to 25°C 39 46
TA = 55 °C 41 80
TA = 85 °C 44 86
TA = 105 °C 49.5 100
TA = 125 °C 60 120
1. Guaranteed by characterization results at 125 °C, unless otherwise specified.
DS10184 Rev 9 61/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
Figure 15. IDD vs VDD, at TA= 25/55/ 85/105/125 °C, Low-power run mode, code running
from RAM, Range 3, MSI (Range 0) at 64 KHz, 0 WS
MSv34794V3
0 WS - 55°C
0 WS - 85°C
0 WS - 105°C
0 WS – 25°C
0 WS - 125°C
VDD (V)
IDD (mA)
0
5.00E-03
1.00E-02
1.50E-02
2.00E-02
2.50E-02
3.00E-02
3.50E-02
1.80 2.00 2.20 2.40 2.60 2.80 3.00 3.20 3.40 3.60
Table 33. Current consumption in Low-power sleep mode
Symbol Parameter Conditions Typ Max(1) Unit
IDD
(LP Sleep)
Supply
current in
Low-power
sleep mode
All peripherals
OFF, VDD from
1.65 to 3.6 V
MSI clock = 65 kHz,
fHCLK = 32 kHz,
Flash OFF
TA = 40 to 25°C 4.7(2) -
µA
MSI clock = 65 kHz,
fHCLK = 32 kHz,
Flash ON
TA = 40 to 25°C 17 23
TA = 85 °C 19.5 63
TA = 105 °C 23 69
TA = 125 °C 32.5 90
MSI clock =65 kHz,
fHCLK = 65 kHz,
Flash ON
TA = 40 to 25°C 17 23
TA = 85 °C 20 63
TA = 105 °C 23.5 69
TA = 125 °C 32.5 90
MSI clock = 131 kHz,
fHCLK = 131 kHz,
Flash ON
TA = 40 to 25°C 19.5 36
TA = 55 °C 20.5 64
TA = 85 °C 22.5 66
TA = 105 °C 26 72
TA = 125 °C 35 95
1. Guaranteed by characterization results at 125 °C, unless otherwise specified.
2. As the CPU is in Sleep mode, the difference between the current consumption with Flash ON and OFF (nearly 12 µA) is
the same whatever the clock frequency.
Electrical characteristics STM32L051x6 STM32L051x8
62/132 DS10184 Rev 9
Figure 16. IDD vs VDD, at TA= 25/55/ 85/105/125 °C, Stop mode with RTC enabled
and running on LSE Low drive
Figure 17. IDD vs VDD, at TA= 25/55/85/105/125 °C, Stop mode with RTC disabled,
all clocks OFF
Table 34. Typical and maximum current consumptions in Stop mode
Symbol Parameter Conditions Typ Max(1)
1. Guaranteed by characterization results at 125 °C, unless otherwise specified.
Unit
IDD (Stop) Supply current in Stop mode
TA = 40 to 25°C 0.41 1
µA
TA = 55°C 0.63 2.1
TA= 85°C 1.7 4.5
TA = 105°C 4 9.6
TA = 125°C 11 24(2)
2. Guaranteed by test in production.
MSv34795V3
IDD (mA)
VDD (V)
55°C
85°C
105°C
25°C
125°C
0
2.00E-03
4.00E-03
6.00E-03
8.00E-03
1.00E-02
1.20E-02
1.80 2.00 2.20 2.40 2.60 2.80 3.00 3.20 3.40 3.60
MSv34796V3
IDD (mA)
0
2.00E-03
4.00E-03
6.00E-03
8.00E-03
1.00E-02
1.20E-02
1.40E-02
1.80 2.00 2.20 2.40 2.60 2.80 3.00 3.20 3.40 3.60
VDD (V)
55 °C
85 °C
105 °C
25 °C
125 °C
DS10184 Rev 9 63/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
Table 35. Typical and maximum current consumptions in Standby mode
Symbol Parameter Conditions Typ Max(1) Unit
IDD
(Standby)
Supply current in Standby
mode
Independent watchdog
and LSI enabled
TA = 40 to 25°C 1.3 1.7
µA
TA = 55 °C - 2.9
TA= 85 °C - 3.3
TA = 105 °C - 4.1
TA = 125 °C - 8.5
Independent watchdog
and LSI OFF
TA = 40 to 25°C 0.29 0.6
TA = 55 °C 0.32 0.9
TA = 85 °C 0.5 2.3
TA = 105 °C 0.94 3
TA = 125 °C 2.6 7
1. Guaranteed by characterization results at 125 °C, unless otherwise specified
Table 36. Average current consumption during Wakeup
Symbol parameter System frequency
Current
consumption
during wakeup
Unit
IDD (Wakeup from
Stop)
Supply current during Wakeup from
Stop mode
HSI 1
mA
HSI/4 0,7
MSI clock = 4,2 MHz 0,7
MSI clock = 1,05 MHz 0,4
MSI clock = 65 KHz 0,1
IDD (Reset) Reset pin pulled down - 0,21
IDD (Power-up) BOR ON - 0,23
IDD (Wakeup from
StandBy)
With Fast wakeup set MSI clock = 2,1 MHz 0,5
With Fast wakeup disabled MSI clock = 2,1 MHz 0,12
Electrical characteristics STM32L051x6 STM32L051x8
64/132 DS10184 Rev 9
On-chip peripheral current consumption
The current consumption of the on-chip peripherals is given in the following tables. The
MCU is placed under the following conditions:
all I/O pins are in input mode with a static value at VDD or VSS (no load)
all peripherals are disabled unless otherwise mentioned
the given value is calculated by measuring the current consumption
with all peripherals clocked OFF
with only one peripheral clocked on
Table 37. Peripheral current consumption in Run or Sleep mode(1)
Peripheral
Typical consumption, VDD = 3.0 V, TA = 25 °C
Unit
Range 1,
VCORE=1.8 V
VOS[1:0] = 01
Range 2,
VCORE=1.5 V
VOS[1:0] = 10
Range 3,
VCORE=1.2 V
VOS[1:0] = 11
Low-power
sleep and
run
APB1
I2C1 11 9.5 7.5 9
µA/MHz
(fHCLK)
I2C2 4 3.5 3 2.5
LPTIM1 10 8.5 6.5 8
LPUART1 8 6.5 5.5 6
SPI2 9 4.5 3.5 4
USART2 14.5 12 9.5 11
TIM2 10.5 8.5 7 9
TIM6 3.5 3 2.5 2
WWDG 3 2 2 2
APB2
ADC1(2) 5.5 5 3.5 4
µA/MHz
(fHCLK)
SPI1 4 3 3 2.5
USART1 14.5 11.5 9.5 12
TIM21 7.5 6 5 5.5
TIM22 7 6 5 6
FIREWALL 1.5 1 1 0.5
DBGMCU 1.5 1 1 0.5
SYSCFG 2.5 2 2 1.5
Cortex-
M0+ core
I/O port
GPIOA 3.5 3 2.5 2.5
µA/MHz
(fHCLK)
GPIOB 3.5 2.5 2 2.5
GPIOC 8.5 6.5 5.5 7
GPIOD 1 0.5 0.5 0.5
AHB
CRC 1.5 1 1 1
µA/MHz
(fHCLK)
FLASH 0(3) 0(3) 0(3) 0(3)
DMA1 10 8 6.5 8.5
DS10184 Rev 9 65/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
All enabled 283 225 222.5 212.5 µA/MHz
(fHCLK)
PWR 2.5 2 2 1 µA/MHz
(fHCLK)
1. Data based on differential IDD measurement between all peripherals OFF an one peripheral with clock
enabled, in the following conditions: fHCLK = 32 MHz (range 1), fHCLK = 16 MHz (range 2), fHCLK = 4 MHz
(range 3), fHCLK = 64kHz (Low-power run/sleep), fAPB1 = fHCLK, fAPB2 = fHCLK, default prescaler value for
each peripheral. The CPU is in Sleep mode in both cases. No I/O pins toggling. Not tested in production.
2. HSI oscillator is OFF for this measure.
3. Current consumption is negligible and close to 0 µA.
Table 37. Peripheral current consumption in Run or Sleep mode(1) (continued)
Peripheral
Typical consumption, VDD = 3.0 V, TA = 25 °C
Unit
Range 1,
VCORE=1.8 V
VOS[1:0] = 01
Range 2,
VCORE=1.5 V
VOS[1:0] = 10
Range 3,
VCORE=1.2 V
VOS[1:0] = 11
Low-power
sleep and
run
Table 38. Peripheral current consumption in Stop and Standby mode(1)
Symbol Peripheral
Typical consumption, TA = 25 °C
Unit
VDD=1.8 V VDD=3.0 V
IDD(PVD / BOR) -0.71.2
µA
IREFINT --1.4
- LSE Low drive(2) 0,1 0,1
- LPTIM1, Input 100 Hz 0,01 0,01
- LPTIM1, Input 1 MHz 6 6
- LPUART1 0,2 0,2
-RTC0,30,48
1. LPTIM peripheral cannot operate in Standby mode.
2. LSE Low drive consumption is the difference between an external clock on OSC32_IN and a quartz between OSC32_IN
and OSC32_OUT.-
Electrical characteristics STM32L051x6 STM32L051x8
66/132 DS10184 Rev 9
6.3.5 Wakeup time from low-power mode
The wakeup times given in the following table are measured with the MSI or HSI16 RC
oscillator. The clock source used to wake up the device depends on the current operating
mode:
Sleep mode: the clock source is the clock that was set before entering Sleep mode
Stop mode: the clock source is either the MSI oscillator in the range configured before
entering Stop mode, the HSI16 or HSI16/4.
Standby mode: the clock source is the MSI oscillator running at 2.1 MHz
All timings are derived from tests performed under ambient temperature and VDD supply
voltage conditions summarized in Table 23.
Table 39. Low-power mode wakeup timings
Symbol Parameter Conditions Typ Max Unit
tWUSLEEP Wakeup from Sleep mode fHCLK = 32 MHz 7 8
Number
of clock
cycles
tWUSLEEP_LP
Wakeup from Low-power sleep mode,
fHCLK = 262 kHz
fHCLK = 262 kHz
Flash memory enabled 78
fHCLK = 262 kHz
Flash memory switched OFF 910
tWUSTOP
Wakeup from Stop mode, regulator in Run
mode
fHCLK = fMSI = 4.2 MHz 5.0 8
µs
fHCLK = fHSI = 16 MHz 4.9 7
fHCLK = fHSI/4 = 4 MHz 8.0 11
Wakeup from Stop mode, regulator in low-
power mode
fHCLK = fMSI = 4.2 MHz
Voltage range 1 5.0 8
fHCLK = fMSI = 4.2 MHz
Voltage range 2 5.0 8
fHCLK = fMSI = 4.2 MHz
Voltage range 3 5.0 8
fHCLK = fMSI = 2.1 MHz 7.3 13
fHCLK = fMSI = 1.05 MHz 13 23
fHCLK = fMSI = 524 kHz 28 38
fHCLK = fMSI = 262 kHz 51 65
fHCLK = fMSI = 131 kHz 100 120
fHCLK = MSI = 65 kHz 190 260
fHCLK = fHSI = 16 MHz 4.9 7
fHCLK = fHSI/4 = 4 MHz 8.0 11
Wakeup from Stop mode, regulator in low-
power mode, code running from RAM
fHCLK = fHSI = 16 MHz 4.9 7
fHCLK = fHSI/4 = 4 MHz 7.9 10
fHCLK = fMSI = 4.2 MHz 4.7 8
tWUSTDBY
Wakeup from Standby mode, FWU bit = 1 fHCLK = MSI = 2.1 MHz 65 130 µs
Wakeup from Standby mode, FWU bit = 0 fHCLK = MSI = 2.1 MHz 2.2 3 ms
DS10184 Rev 9 67/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
6.3.6 External clock source characteristics
High-speed external user clock generated from an external source
In bypass mode the HSE oscillator is switched off and the input pin is a standard GPIO.The
external clock signal has to respect the I/O characteristics in Section 6.3.12. However, the
recommended clock input waveform is shown in Figure 18.
Figure 18. High-speed external clock source AC timing diagram
Table 40. High-speed external user clock characteristics(1)
1. Guaranteed by design.
Symbol Parameter Conditions Min Typ Max Unit
fHSE_ext
User external clock source
frequency
CSS is ON or
PLL is used 1832MHz
CSS is OFF,
PLL not used 0832MHz
VHSEH OSC_IN input pin high level voltage
-
0.7VDD -V
DD V
VHSEL OSC_IN input pin low level voltage VSS -0.3V
DD
tw(HSE)
tw(HSE)
OSC_IN high or low time 12 - -
ns
tr(HSE)
tf(HSE)
OSC_IN rise or fall time - - 20
Cin(HSE) OSC_IN input capacitance - 2.6 - pF
DuCy(HSE) Duty cycle 45 - 55 %
ILOSC_IN Input leakage current VSS VIN VDD --±1µA
ai18232c
OSC _ IN
EXTERNAL
STM32Lxx
CLOCK SOURCE
VHSEH
tf(HSE) tW(HSE)
IL
90%
10%
THSE
t
tr(HSE) tW(HSE)
fHSE_ext
VHSEL
Electrical characteristics STM32L051x6 STM32L051x8
68/132 DS10184 Rev 9
Low-speed external user clock generated from an external source
The characteristics given in the following table result from tests performed using a low-
speed external clock source, and under ambient temperature and supply voltage conditions
summarized in Table 23.
Figure 19. Low-speed external clock source AC timing diagram
Table 41. Low-speed external user clock characteristics(1)
1. Guaranteed by design, not tested in production
Symbol Parameter Conditions Min Typ Max Unit
fLSE_ext
User external clock source
frequency
-
1 32.768 1000 kHz
VLSEH
OSC32_IN input pin high level
voltage 0.7VDD -V
DD
V
VLSEL
OSC32_IN input pin low level
voltage VSS -0.3V
DD
tw(LSE)
tw(LSE)
OSC32_IN high or low time 465 - -
ns
tr(LSE)
tf(LSE)
OSC32_IN rise or fall time - - 10
CIN(LSE) OSC32_IN input capacitance - - 0.6 - pF
DuCy(LSE) Duty cycle - 45 - 55 %
ILOSC32_IN Input leakage current VSS VIN VDD --±1µA
ai18233c
OSC 32_ IN
EXTERNAL
STM32Lxx
CLOCK SOURCE
VLSEH
tf(LSE) tW(LSE)
IL
90%
10%
TLSE
t
tr(LSE) tW(LSE)
fLSE_ext
VLSEL
DS10184 Rev 9 69/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
High-speed external clock generated from a crystal/ceramic resonator
The high-speed external (HSE) clock can be supplied with a 1 to 25 MHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on
characterization results obtained with typical external components specified in Table 42. In
the application, the resonator and the load capacitors have to be placed as close as
possible to the oscillator pins in order to minimize output distortion and startup stabilization
time. Refer to the crystal resonator manufacturer for more details on the resonator
characteristics (frequency, package, accuracy).
For CL1 and CL2, it is recommended to use high-quality external ceramic capacitors in the
5 pF to 25 pF range (typ.), designed for high-frequency applications, and selected to match
the requirements of the crystal or resonator (see Figure 20). CL1 and CL2 are usually the
same size. The crystal manufacturer typically specifies a load capacitance which is the
series combination of CL1 and CL2. PCB and MCU pin capacitance must be included (10 pF
can be used as a rough estimate of the combined pin and board capacitance) when sizing
CL1 and CL2. Refer to the application note AN2867 “Oscillator design guide for ST
microcontrollers” available from the ST website www.st.com.
Figure 20. HSE oscillator circuit diagram
Table 42. HSE oscillator characteristics(1)
1. Guaranteed by design.
Symbol Parameter Conditions Min Typ Max Unit
fOSC_IN Oscillator frequency - 1 25 MHz
RFFeedback resistor - - 200 - kΩ
Gm
Maximum critical crystal
transconductance Startup - - 700 µA
/V
tSU(HSE)
(2)
2. Guaranteed by characterization results. tSU(HSE) is the startup time measured from the moment it is
enabled (by software) to a stabilized 8 MHz oscillation is reached. This value is measured for a standard
crystal resonator and it can vary significantly with the crystal manufacturer.
Startup time VDD is stabilized - 2 - ms
OSC_OUT
OSC_IN
f
HSE
to core
C
L1
C
L2
R
F
STM32
Resonator
Consumption
control
g
m
R
m
C
m
L
m
C
O
Resonator
ai18235b
Electrical characteristics STM32L051x6 STM32L051x8
70/132 DS10184 Rev 9
Low-speed external clock generated from a crystal/ceramic resonator
The low-speed external (LSE) clock can be supplied with a 32.768 kHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on
characterization results obtained with typical external components specified in Table 43. In
the application, the resonator and the load capacitors have to be placed as close as
possible to the oscillator pins in order to minimize output distortion and startup stabilization
time. Refer to the crystal resonator manufacturer for more details on the resonator
characteristics (frequency, package, accuracy).
Note: For information on selecting the crystal, refer to the application note AN2867 “Oscillator
design guide for ST microcontrollers” available from the ST website www.st.com.
Figure 21. Typical application with a 32.768 kHz crystal
Note: An external resistor is not required between OSC32_IN and OSC32_OUT and it is forbidden
to add one.
Table 43. LSE oscillator characteristics(1)
Symbol Parameter Conditions(2) Min(2) Typ Max Unit
fLSE LSE oscillator frequency - 32.768 - kHz
Gm
Maximum critical crystal
transconductance
LSEDRV[1:0]=00
lower driving capability --0.5
µA/V
LSEDRV[1:0]= 01
medium low driving capability - - 0.75
LSEDRV[1:0] = 10
medium high driving capability --1.7
LSEDRV[1:0]=11
higher driving capability --2.7
tSU(LSE)(3) Startup time VDD is stabilized - 2 - s
1. Guaranteed by design.
2. Refer to the note and caution paragraphs below the table, and to the application note AN2867 “Oscillator design guide for
ST microcontrollers”.
3. Guaranteed by characterization results. tSU(LSE) is the startup time measured from the moment it is enabled (by software)
to a stabilized 32.768 kHz oscillation is reached. This value is measured for a standard crystal resonator and it can vary
significantly with the crystal manufacturer. To increase speed, address a lower-drive quartz with a high- driver mode.
MS30253V2
OSC32_IN
OSC32_OUT
Drive
programmable
amplifier
fLSE
32.768 kHz
resonator
Resonator with integrated
capacitors
CL1
CL2
DS10184 Rev 9 71/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
6.3.7 Internal clock source characteristics
The parameters given in Table 44 are derived from tests performed under ambient
temperature and VDD supply voltage conditions summarized in Table 23.
High-speed internal 16 MHz (HSI16) RC oscillator
Figure 22. HSI16 minimum and maximum value versus temperature
Table 44. 16 MHz HSI16 oscillator characteristics
Symbol Parameter Conditions Min Typ Max Unit
fHSI16 Frequency VDD = 3.0 V - 16 - MHz
TRIM(1)(2)
1. The trimming step differs depending on the trimming code. It is usually negative on the codes which are
multiples of 16 (0x00, 0x10, 0x20, 0x30...0xE0).
HSI16 user-
trimmed resolution
Trimming code is not a multiple of 16 - ± 0.4 0.7 %
Trimming code is a multiple of 16 - - ± 1.5 %
ACCHSI16
(2)
2. Guaranteed by characterization results.
Accuracy of the
factory-calibrated
HSI16 oscillator
VDDA = 3.0 V, TA = 25 °C -1(3)
3. Guaranteed by test in production.
-1
(3) %
VDDA = 3.0 V, TA = 0 to 55 °C -1.5 - 1.5 %
VDDA = 3.0 V, TA = -10 to 70 °C -2 - 2 %
VDDA = 3.0 V, TA = -10 to 85 °C -2.5 - 2 %
VDDA = 3.0 V, TA = -10 to 105 °C -4 - 2 %
VDDA = 1.65 V to 3.6 V
TA = 40 to 125 °C -5.45 - 3.25 %
tSU(HSI16)(2) HSI16 oscillator
startup time - - 3.7 6 µs
IDD(HSI16)(2) HSI16 oscillator
power consumption - - 100 140 µA
MSv34791V1
-6.00%
-5.00%
-4.00%
-3.00%
-2.00%
-1.00%
0.00%
1.00%
2.00%
3.00%
4.00%
-60 -40 -20 0 20 40 60 80 100 120 140
1.65V min
3V typ
3.6V max
1.65V max
3.6V min
Electrical characteristics STM32L051x6 STM32L051x8
72/132 DS10184 Rev 9
Low-speed internal (LSI) RC oscillator
Multi-speed internal (MSI) RC oscillator
Table 45. LSI oscillator characteristics
Symbol Parameter Min Typ Max Unit
fLSI(1)
1. Guaranteed by test in production.
LSI frequency 26 38 56 kHz
DLSI(2)
2. This is a deviation for an individual part, once the initial frequency has been measured.
LSI oscillator frequency drift
0°C TA 85°C -10 - 4 %
tsu(LSI)(3)
3. Guaranteed by design.
LSI oscillator startup time - - 200 µs
IDD(LSI)(3) LSI oscillator power consumption - 400 510 nA
Table 46. MSI oscillator characteristics
Symbol Parameter Condition Typ Max Unit
fMSI
Frequency after factory calibration, done at
VDD= 3.3 V and TA = 25 °C
MSI range 0 65.5 -
kHz
MSI range 1 131 -
MSI range 2 262 -
MSI range 3 524 -
MSI range 4 1.05 -
MHzMSI range 5 2.1 -
MSI range 6 4.2 -
ACCMSI Frequency error after factory calibration - ±0.5 - %
DTEMP(MSI)(1)
MSI oscillator frequency drift
0 °C TA 85 °C -±3-
%
MSI oscillator frequency drift
VDD = 3.3 V, 40 °C TA 110 °C
MSI range 0 8.9 +7.0
MSI range 1 7.1 +5.0
MSI range 2 6.4 +4.0
MSI range 3 6.2 +3.0
MSI range 4 5.2 +3.0
MSI range 5 4.8 +2.0
MSI range 6 4.7 +2.0
DVOLT(MSI)(1) MSI oscillator frequency drift
1.65 V VDD 3.6 V, TA = 25 °C --2.5%/V
DS10184 Rev 9 73/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
IDD(MSI)(2) MSI oscillator power consumption
MSI range 0 0.75 -
µA
MSI range 1 1 -
MSI range 2 1.5 -
MSI range 3 2.5 -
MSI range 4 4.5 -
MSI range 5 8 -
MSI range 6 15 -
tSU(MSI) MSI oscillator startup time
MSI range 0 30 -
µs
MSI range 1 20 -
MSI range 2 15 -
MSI range 3 10 -
MSI range 4 6 -
MSI range 5 5 -
MSI range 6,
Voltage range 1
and 2
3.5 -
MSI range 6,
Voltage range 3 5-
tSTAB(MSI)(2) MSI oscillator stabilization time
MSI range 0 - 40
µs
MSI range 1 - 20
MSI range 2 - 10
MSI range 3 - 4
MSI range 4 - 2.5
MSI range 5 - 2
MSI range 6,
Voltage range 1
and 2
-2
MSI range 3,
Voltage range 3 -3
fOVER(MSI) MSI oscillator frequency overshoot
Any range to
range 5 -4
MHz
Any range to
range 6 -6
1. This is a deviation for an individual part, once the initial frequency has been measured.
2. Guaranteed by characterization results.
Table 46. MSI oscillator characteristics (continued)
Symbol Parameter Condition Typ Max Unit
Electrical characteristics STM32L051x6 STM32L051x8
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6.3.8 PLL characteristics
The parameters given in Table 47 are derived from tests performed under ambient
temperature and VDD supply voltage conditions summarized in Table 23.
6.3.9 Memory characteristics
RAM memory
Flash memory and data EEPROM
Table 47. PLL characteristics
Symbol Parameter
Value
Unit
Min Typ Max(1)
1. Guaranteed by characterization results.
fPLL_IN
PLL input clock(2)
2. Take care of using the appropriate multiplier factors so as to have PLL input clock values compatible with
the range defined by fPLL_OUT.
2- 24MHz
PLL input clock duty cycle 45 - 55 %
fPLL_OUT PLL output clock 2 - 32 MHz
tLOCK
PLL input = 16 MHz
PLL VCO = 96 MHz - 115 160 µs
Jitter Cycle-to-cycle jitter - ±
600 ps
IDDA(PLL) Current consumption on VDDA - 220 450
µA
IDD(PLL) Current consumption on VDD - 120 150
Table 48. RAM and hardware registers
Symbol Parameter Conditions Min Typ Max Unit
VRM Data retention mode(1)
1. Minimum supply voltage without losing data stored in RAM (in Stop mode or under Reset) or in hardware
registers (only in Stop mode).
STOP mode (or RESET) 1.65 - - V
Table 49. Flash memory and data EEPROM characteristics
Symbol Parameter Conditions Min Typ Max(1) Unit
VDD
Operating voltage
Read / Write / Erase -1.65-3.6V
tprog
Programming time for
word or half-page
Erasing - 3.28 3.94
ms
Programming - 3.28 3.94
DS10184 Rev 9 75/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
IDD
Average current during
the whole programming /
erase operation
TA = 25 °C, VDD = 3.6 V
- 500 700 µA
Maximum current (peak)
during the whole
programming / erase
operation
-1.52.5mA
1. Guaranteed by design.
Table 50. Flash memory and data EEPROM endurance and retention
Symbol Parameter Conditions
Value
Unit
Min(1)
1. Guaranteed by characterization results.
NCYC(2)
Cycling (erase / write)
Program memory
TA = -40°C to 105 °C
10
kcycles
Cycling (erase / write)
EEPROM data memory 100
Cycling (erase / write)
Program memory
TA = -40°C to 125 °C
0.2
Cycling (erase / write)
EEPROM data memory 2
tRET(2)
2. Characterization is done according to JEDEC JESD22-A117.
Data retention (program memory) after
10 kcycles at TA = 85 °C
TRET = +85 °C
30
years
Data retention (EEPROM data memory)
after 100 kcycles at TA = 85 °C 30
Data retention (program memory) after
10 kcycles at TA = 105 °C
TRET = +105 °C
10
Data retention (EEPROM data memory)
after 100 kcycles at TA = 105 °C
Data retention (program memory) after
200 cycles at TA = 125 °C
TRET = +125 °C
Data retention (EEPROM data memory)
after 2 kcycles at TA = 125 °C
Table 49. Flash memory and data EEPROM characteristics
Symbol Parameter Conditions Min Typ Max(1) Unit
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6.3.10 EMC characteristics
Susceptibility tests are performed on a sample basis during device characterization.
Functional EMS (electromagnetic susceptibility)
While a simple application is executed on the device (toggling 2 LEDs through I/O ports).
the device is stressed by two electromagnetic events until a failure occurs. The failure is
indicated by the LEDs:
Electrostatic discharge (ESD) (positive and negative) is applied to all device pins until
a functional disturbance occurs. This test is compliant with the IEC 61000-4-2 standard.
FTB: A Burst of Fast Transient voltage (positive and negative) is applied to VDD and
VSS through a 100 pF capacitor, until a functional disturbance occurs. This test is
compliant with the IEC 61000-4-4 standard.
A device reset allows normal operations to be resumed.
The test results are given in Table 51. They are based on the EMS levels and classes
defined in application note AN1709.
Designing hardened software to avoid noise problems
EMC characterization and optimization are performed at component level with a typical
application environment and simplified MCU software. It should be noted that good EMC
performance is highly dependent on the user application and the software in particular.
Therefore it is recommended that the user applies EMC software optimization and
prequalification tests in relation with the EMC level requested for his application.
Software recommendations
The software flowchart must include the management of runaway conditions such as:
Corrupted program counter
Unexpected reset
Critical data corruption (control registers...)
Prequalification trials
Most of the common failures (unexpected reset and program counter corruption) can be
reproduced by manually forcing a low state on the NRST pin or the oscillator pins for 1
second.
Table 51. EMS characteristics
Symbol Parameter Conditions Level/
Class
VFESD
Voltage limits to be applied on any I/O pin to
induce a functional disturbance
VDD = 3.3 V, LQFP64, TA = +25 °C,
fHCLK = 32 MHz
conforms to IEC 61000-4-2
3B
VEFTB
Fast transient voltage burst limits to be
applied through 100 pF on VDD and VSS
pins to induce a functional disturbance
VDD = 3.3 V, LQFP64, TA = +25 °C,
fHCLK = 32 MHz
conforms to IEC 61000-4-4
4A
DS10184 Rev 9 77/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
To complete these trials, ESD stress can be applied directly on the device, over the range of
specification values. When unexpected behavior is detected, the software can be hardened
to prevent unrecoverable errors occurring (see application note AN1015).
Electromagnetic Interference (EMI)
The electromagnetic field emitted by the device are monitored while a simple application is
executed (toggling 2 LEDs through the I/O ports). This emission test is compliant with
IEC 61967-2 standard which specifies the test board and the pin loading.
Table 52. EMI characteristics
Symbol Parameter Conditions Monitored
frequency band
Max vs. fosc/fCPU
Unit
8 MHz/
4 MHz
8 MHz/
16 MHz
8 MHz/
32 MHz
SEMI Peak level
VDD = 3.6 V,
TA = 25 °C,
compliant with IEC
61967-2
0.1 to 30 MHz -21 -15 -12
dBµV30 to 130 MHz -14 -12 -1
130 MHz to 1GHz -10 -11 -7
EMI Level 1 1 1 -
Electrical characteristics STM32L051x6 STM32L051x8
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6.3.11 Electrical sensitivity characteristics
Based on three different tests (ESD, LU) using specific measurement methods, the device is
stressed in order to determine its performance in terms of electrical sensitivity.
Electrostatic discharge (ESD)
Electrostatic discharges (a positive then a negative pulse separated by 1 second) are
applied to the pins of each sample according to each pin combination. The sample size
depends on the number of supply pins in the device (3 parts × (n+1) supply pins). This test
conforms to the ANSI/JEDEC standard.
Static latch-up
Two complementary static tests are required on six parts to assess the latch-up
performance:
A supply overvoltage is applied to each power supply pin
A current injection is applied to each input, output and configurable I/O pin
These tests are compliant with EIA/JESD 78A IC latch-up standard.
Table 53. ESD absolute maximum ratings
Symbol Ratings Conditions Class Maximum
value(1)
1. Guaranteed by characterization results.
Unit
VESD(HBM)
Electrostatic discharge
voltage (human body model)
TA = +25 °C,
conforming to
ANSI/JEDEC JS-001
22000
V
VESD(CDM)
Electrostatic discharge
voltage (charge device
model)
TA = +25 °C,
conforming to
ANSI/ESD STM5.3.1.
C4 500
Table 54. Electrical sensitivities
Symbol Parameter Conditions Class
LU Static latch-up class TA = +125 °C conforming to JESD78A II level A
DS10184 Rev 9 79/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
6.3.12 I/O current injection characteristics
As a general rule, current injection to the I/O pins, due to external voltage below VSS or
above VDD (for standard pins) should be avoided during normal product operation.
However, in order to give an indication of the robustness of the microcontroller in cases
when abnormal injection accidentally happens, susceptibility tests are performed on a
sample basis during device characterization.
Functional susceptibility to I/O current injection
While a simple application is executed on the device, the device is stressed by injecting
current into the I/O pins programmed in floating input mode. While current is injected into
the I/O pin, one at a time, the device is checked for functional failures.
The failure is indicated by an out of range parameter: ADC error above a certain limit (higher
than 5 LSB TUE), out of conventional limits of induced leakage current on adjacent pins (out
of –5 µA/+0 µA range), or other functional failure (for example reset occurrence oscillator
frequency deviation).
The test results are given in the Table 55.
Table 55. I/O current injection susceptibility
Symbol Description
Functional susceptibility
Unit
Negative
injection
Positive
injection
IINJ
Injected current on BOOT0 -0 NA(1)
1. Current injection is not possible.
mA
Injected current on PA0, PA4, PA5, PA11,
PA12, PC15, PH0 and PH1 -5 0
Injected current on any other FT, FTf pins -5 (2)
2. It is recommended to add a Schottky diode (pin to ground) to analog pins which may potentially inject
negative currents.
NA(1)
Injected current on any other pins -5 (2) +5
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6.3.13 I/O port characteristics
General input/output characteristics
Unless otherwise specified, the parameters given in Table 56 are derived from tests
performed under the conditions summarized in Table 23. All I/Os are CMOS and TTL
compliant.
Table 56. I/O static characteristics
Symbol Parameter Conditions Min Typ Max Unit
VIL Input low level voltage
TC, FT, FTf, RST
I/Os - - 0.3VDD
V
BOOT0 pin - - 0.14VDD(1)
VIH Input high level voltage All I/Os 0.7 VDD --
Vhys
I/O Schmitt trigger voltage hysteresis
(2)
Standard I/Os - 10% VDD(3) -
BOOT0 pin - 0.01 -
Ilkg Input leakage current (4)
VSS VIN VDD
All I/Os except for
PA11, PA12, BOOT0
and FTf I/Os
--±50
nA
VSS VIN VDD,
PA11 and PA12 I/Os - - -50/+250
VSS VIN VDD
FTf I/Os - - ±100
VDD VIN 5 V
All I/Os except for
PA11, PA12, BOOT0
and FTf I/Os
- - 200
nA
VDD VIN 5 V
FTf I/Os - - 500
VDD VIN 5 V
PA11, PA12 and
BOOT0
--10µA
RPU Weak pull-up equivalent resistor(5) VIN = VSS 25 45 65 kΩ
RPD Weak pull-down equivalent resistor(5) VIN = VDD 25 45 65 kΩ
CIO I/O pin capacitance - - 5 - pF
1. Guaranteed by characterization.
2. Hysteresis voltage between Schmitt trigger switching levels. Guaranteed by characterization results.
3. With a minimum of 200 mV. Guaranteed by characterization results.
4. The max. value may be exceeded if negative current is injected on adjacent pins.
5. Pull-up and pull-down resistors are designed with a true resistance in series with a switchable PMOS/NMOS. This
MOS/NMOS contribution to the series resistance is minimum (~10% order).
DS10184 Rev 9 81/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
Figure 23. VIH/VIL versus VDD (CMOS I/Os)
Figure 24. VIH/VIL versus VDD (TTL I/Os)
Output driving current
The GPIOs (general purpose input/outputs) can sink or source up to ±8 mA, and sink or
source up to ±15 mA with the non-standard VOL/VOH specifications given in Table 57.
In the user application, the number of I/O pins which can drive current must be limited to
respect the absolute maximum rating specified in Section 6.2:
The sum of the currents sourced by all the I/Os on VDD, plus the maximum Run
consumption of the MCU sourced on VDD, cannot exceed the absolute maximum rating
IVDD(Σ) (see Table 21).
The sum of the currents sunk by all the I/Os on VSS plus the maximum Run
consumption of the MCU sunk on VSS cannot exceed the absolute maximum rating
IVSS(Σ) (see Table 21).
MSv34789V1
VDD (V)
VIHmin 2.0
VILmax 0.7
VIL/VIH (V)
1.3
2.0 3.6
CMOS standard requirements V
IHmin
= 0.7V
DD
V
ILmax
= 0.3V
DD
0.6
2.7 3.0 3.3
CMOS standard requirements VILmax = 0.3VDD
V
IHmin
= 0.39V
DD
+0.59 (all pins
except BOOT0, PC15, PH0/1
V
IHmin
= 0.45V
DD
+0.38 for
BOOT0, PC15, PH0/1
Input range not
guaranteed
MSv34790V1
VDD (V)
VIHmin 2.0
VILmax 0.8
VIL/VIH (V)
1.3
2.0 3.6
TTL standard requirements VIHmin = 2 V
V
ILmax
= 0.3V
DD
0.7
2.7 3.0 3.3
TTL standard requirements VILmax = 0.8 V
Input range not
guaranteed
V
IHmin
= 0.39V
DD
+0.59 (all pins
except BOOT0, PC15, PH0/1
V
IHmin
= 0.45V
DD
+0.38 for
BOOT0, PC15, PH0/1
Electrical characteristics STM32L051x6 STM32L051x8
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Output voltage levels
Unless otherwise specified, the parameters given in Table 57 are derived from tests
performed under ambient temperature and VDD supply voltage conditions summarized in
Table 23. All I/Os are CMOS and TTL compliant.
Table 57. Output voltage characteristics
Symbol Parameter Conditions Min Max Unit
VOL(1)
1. The IIO current sunk by the device must always respect the absolute maximum rating specified in Table 21.
The sum of the currents sunk by all the I/Os (I/O ports and control pins) must always be respected and
must not exceed ΣIIO(PIN).
Output low level voltage for an I/O
pin CMOS port(2),
IIO = +8 mA
2.7 V VDD 3.6 V
2. TTL and CMOS outputs are compatible with JEDEC standards JESD36 and JESD52.
-0.4
V
VOH(3)
3. The IIO current sourced by the device must always respect the absolute maximum rating specified in
Table 21. The sum of the currents sourced by all the I/Os (I/O ports and control pins) must always be
respected and must not exceed ΣIIO(PIN).
Output high level voltage for an I/O
pin VDD-0.4 -
VOL (1) Output low level voltage for an I/O
pin
TTL port(2),
IIO =+ 8 mA
2.7 V VDD 3.6 V
-0.4
VOH (3)(4)
4. Guaranteed by characterization results.
Output high level voltage for an I/O
pin
TTL port(2),
IIO = -6 mA
2.7 V VDD 3.6 V
2.4 -
VOL(1)(4) Output low level voltage for an I/O
pin
IIO = +15 mA
2.7 V VDD 3.6 V -1.3
VOH(3)(4) Output high level voltage for an I/O
pin
IIO = -15 mA
2.7 V VDD 3.6 V VDD-1.3 -
VOL(1)(4) Output low level voltage for an I/O
pin
IIO = +4 mA
1.65 V VDD < 3.6 V -0.45
VOH(3)(4) Output high level voltage for an I/O
pin
IIO = -4 mA
1.65 V VDD 3.6 V VDD-0.45 -
VOLFM+(1)(4) Output low level voltage for an FTf
I/O pin in Fm+ mode
IIO = 20 mA
2.7 V VDD 3.6 V -0.4
IIO = 10 mA
1.65 V VDD 3.6 V -0.4
DS10184 Rev 9 83/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
Input/output AC characteristics
The definition and values of input/output AC characteristics are given in Figure 25 and
Table 58, respectively.
Unless otherwise specified, the parameters given in Table 58 are derived from tests
performed under ambient temperature and VDD supply voltage conditions summarized in
Table 23.
Table 58. I/O AC characteristics(1)
OSPEEDRx[1:0]
bit value(1) Symbol Parameter Conditions Min Max(2) Unit
00
fmax(IO)out Maximum frequency(3) CL = 50 pF, VDD = 2.7 V to 3.6 V - 400
kHz
CL = 50 pF, VDD = 1.65 V to 2.7 V - 100
tf(IO)out
tr(IO)out
Output rise and fall time
CL = 50 pF, VDD = 2.7 V to 3.6 V - 125
ns
CL = 50 pF, VDD = 1.65 V to 2.7 V - 320
01
fmax(IO)out Maximum frequency(3) CL = 50 pF, VDD = 2.7 V to 3.6 V - 2
MHz
CL = 50 pF, VDD = 1.65 V to 2.7 V - 0.6
tf(IO)out
tr(IO)out
Output rise and fall time
CL = 50 pF, VDD = 2.7 V to 3.6 V - 30
ns
CL = 50 pF, VDD = 1.65 V to 2.7 V - 65
10
Fmax(IO)out Maximum frequency(3) CL = 50 pF, VDD = 2.7 V to 3.6 V - 10
MHz
CL = 50 pF, VDD = 1.65 V to 2.7 V - 2
tf(IO)out
tr(IO)out
Output rise and fall time
CL = 50 pF, VDD = 2.7 V to 3.6 V - 13
ns
CL = 50 pF, VDD = 1.65 V to 2.7 V - 28
11
Fmax(IO)out Maximum frequency(3) CL = 30 pF, VDD = 2.7 V to 3.6 V - 35
MHz
CL = 50 pF, VDD = 1.65 V to 2.7 V - 10
tf(IO)out
tr(IO)out
Output rise and fall time
CL = 30 pF, VDD = 2.7 V to 3.6 V - 6
ns
CL = 50 pF, VDD = 1.65 V to 2.7 V - 17
Fm+
configuration(4)
fmax(IO)out Maximum frequency(3)
CL = 50 pF, VDD = 2.5 V to 3.6 V
-1MHz
tf(IO)out Output fall time - 10
ns
tr(IO)out Output rise time - 30
fmax(IO)out Maximum frequency(3)
CL = 50 pF, VDD = 1.65 V to 3.6 V
-350KHz
tf(IO)out Output fall time - 15
ns
tr(IO)out Output rise time - 60
-t
EXTIpw
Pulse width of external
signals detected by the
EXTI controller
-8-ns
1. The I/O speed is configured using the OSPEEDRx[1:0] bits. Refer to the line reference manual for a description of GPIO Port
configuration register.
2. Guaranteed by design.
3. The maximum frequency is defined in Figure 25.
4. When Fm+ configuration is set, the I/O speed control is bypassed. Refer to the line reference manual for a detailed
description of Fm+ I/O configuration.
Electrical characteristics STM32L051x6 STM32L051x8
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Figure 25. I/O AC characteristics definition
6.3.14 NRST pin characteristics
The NRST pin input driver uses CMOS technology. It is connected to a permanent pull-up
resistor, RPU , except when it is internally driven low (see Table 59).
Unless otherwise specified, the parameters given in Table 59 are derived from tests
performed under ambient temperature and VDD supply voltage conditions summarized in
Table 23.
ai14131d
10%
90%
50%
tr(IO)out
OUTPUT
EXTERNAL
ON CL
Maximum frequency is achieved if (tr + tf) ≤ (2/3)T and if the duty cycle is (45-55%)
when loaded by CL specified in the table “ I/O AC characteristics”.
10%
50%
90%
T
tf(IO)out
Table 59. NRST pin characteristics
Symbol Parameter Conditions Min Typ Max Unit
VIL(NRST)(1)
1. Guaranteed by design.
NRST input low level voltage - VSS -0.8
V
VIH(NRST)(1) NRST input high level voltage - 1.4 - VDD
VOL(NRST)(1) NRST output low level
voltage
IOL = 2 mA
2.7 V < VDD < 3.6 V --
0.4
IOL = 1.5 mA
1.65 V < VDD < 2.7 V --
Vhys(NRST)(1) NRST Schmitt trigger voltage
hysteresis --10%V
DD(2)
2. 200 mV minimum value
-mV
RPU
Weak pull-up equivalent
resistor(3)
3. The pull-up is designed with a true resistance in series with a switchable PMOS. This PMOS contribution to
the series resistance is around 10%.
VIN = VSS 25 45 65 kΩ
VF(NRST)(1) NRST input filtered pulse - - - 50 ns
VNF(NRST)(1) NRST input not filtered pulse - 350 - - ns
DS10184 Rev 9 85/132
STM32L051x6 STM32L051x8 Electrical characteristics
100
Figure 26. Recommended NRST pin protection
1. The reset network protects the device against parasitic resets.
2. The external capacitor must be placed as close as possible to the device.
3. The user must ensure that the level on the NRST pin can go below the VIL(NRST) max level specified in
Table 59. Otherwise the reset will not be taken into account by the device.
6.3.15 12-bit ADC characteristics
Unless otherwise specified, the parameters given in Table 60 are derived from tests
performed under ambient temperature, fPCLK frequency and VDDA supply voltage conditions
summarized in Table 23: General operating conditions.
Note: It is recommended to perform a calibration after each power-up.
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