GG25L Datasheet by STMicroelectronics

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This is information on a product in full production.
February 2014 DocID025995 Rev 1 1/28
GG25L
Gas gauge IC with alarm output
Datasheet - production data
Features
OptimGaugeTM algorithm
0.25% accuracy battery voltage monitoring
Coulomb counter and voltage-mode gas gauge
operations
Robust initial open-circuit-voltage (OCV)
measurement at power up with debounce
delay
Low battery level alarm output with
programmable thresholds
Internal temperature sensor
Battery swap detection
Low power: 45 µA in power-saving mode, 2 µA
max in standby mode
1.4 x 2.0 mm 10-bump CSP package
Applications
Wearable
Fitness and healthcare
Portable medical equipment
Description
The GG25L includes the hardware functions
required to implement a low-cost gas gauge for
battery monitoring. The GG25L uses current
sensing, Coulomb counting and accurate
measurements of the battery voltage to estimate
the state-of-charge (SOC) of the battery. An
internal temperature sensor simplifies
implementation of temperature compensation.
An alarm output signals a low SOC condition and
can also indicate low battery voltage. The alarm
threshold levels are programmable.
The GG25L offers advanced features to ensure
high performance gas gauging in all application
conditions.
CSP (1.4 x 2.0 mm)
Table 1. Device summary
Order code Temperature range Package Packing Marking
GG25LJ (1)
-40 °C to +85 °C CSP-12 Tape and reel
O22
GG25LAJ (2) O23
1. 4.35 V battery option
2. 4.20 V battery option
www.st.com
Contents GG25L
2/28 DocID025995 Rev 1
Contents
1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 4
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1 Battery monitoring functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1.1 Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1.2 Battery voltage monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1.3 Internal temperature monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.1.4 Current sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.2 GG25L gas gauge architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.2.1 Coulomb counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.2.2 Voltage gas gauge algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.2.3 Mixed mode gas gauge system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.3 Low battery alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.4 Power-up and battery swap detection . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.5 Improving accuracy of the initial OCV measurement with
the advanced functions of BATD/CD and RSTIO pins . . . . . . . . . . . . . . . 17
6.5.1 BATD and RSTIO pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7 I²C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1 Read and write operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.2 Register map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.2.1 Register map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.2.2 Register description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
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DocID025995 Rev 1 3/28
GG25L Block diagram
28
1 Block diagram
Figure 1. GG25L internal block diagram
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Pin assignment GG25L
4/28 DocID025995 Rev 1
2 Pin assignment
3 Absolute maximum ratings and operating conditions
Table 2. GG25L pin description
Pin
CSP
bump Pin name Type(1)
1. I = input, 0 = output, OD = open drain, A = analog, D = digital, NC = not connected
Function
1 A1 ALM I/OD Alarm signal output, open drain,
external pull-up with resistor
2 B1 SDA I/OD I²C serial data
3 C1 SCL I_D I²C serial clock
4 D1 GND Ground Analog and digital ground
5D2 NC -NC
6 D3 CG I_A Current sensing input
7 C3 RSTIO I/OD Reset sense input & reset control output (open drain)
8 B2 BATD/CD I/OA Battery charge inhibit (active high output)
Battery detection (input)
9 B3 VCC Supply Power supply
10 A3 VIN I_A Battery voltage sensing input
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
VCCMAX Maximum voltage on VCC pin 6
V
VIO Voltage on I/O pins -0.3 to 6
TSTG Storage temperature -55 to 150
°C
TJMaximum junction temperature 150
ESD Electrostatic discharge (HBM: human body model) 2 kV
Table 4. Operating conditions
Symbol Parameter Value Unit
VCC Operating supply voltage on VCC 2.7 to 4.5
V
VMIN Minimum voltage on VCC for RAM content retention 2.0
TOPER Operating free air temperature range
-40 to 85
°C
TPERF -20 to 70
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GG25L Electrical characteristics
28
4 Electrical characteristics
Table 5. Electrical characteristics (2.7 V < VCC < 4.5 V, -20C to 70C)
Symbol Parameter Conditions Min Typ Max Units
Supply
ICC Operating current consumption
Average value over 4 s in
power-saving voltage
mode
45 60
µA
Average value over 4 s in
mixed mode 100
ISTBY Current consumption in standby Standby mode,
inputs = 0 V 2
IPDN Current consumption in power-down VCC < UVLOTH,
inputs = 0 V 1
UVLOTH Undervoltage threshold (VCC decreasing) 2.5 2.6 2.7 V
UVLOHYST Undervoltage threshold hysteresis 100 mV
POR Power-on reset threshold (VCC decreasing) 2.0 V
Current sensing
Vin_gg Input voltage range -40 +40 mV
IIN Input current for CG pin 500 nA
ADC_res AD converter granularity 5.88 µV
ADC_offset AD converter offset CG = 0 V -3 3 LSB
ADC_time AD conversion time 500 ms
ADC_acc AD converter gain accuracy at full
scale (using external sense resistor)
25 °C 0.5
%
Over temperature range 1
FOSC Internal time base frequency 32768 Hz
Osc_acc Internal time base accuracy
25 °C, VCC = 3.6 V 2
%
Over temperature and
voltage ranges 2.5
Cur_res Current register LSB value 5.88 µV
CC
Electrical characteristics GG25L
6/28 DocID025995 Rev 1
Battery voltage and temperature measurement
Vin_adc Input voltage range VCC = 4.5 V 0 4.5 V
LSB LSB value
Voltage measurement 2.20 mV
Temperature measurement 1 °C
ADC_time AD conversion time 250 ms
Volt_acc Battery voltage measurement accuracy
2.7 V < Vin < 4.5 V,
VCC = Vin 25 °C -0.25 +0.25
%
Over temperature range -0.5 +0.5
Temp_acc Internal temperature sensor accuracy -3 3 °C
Digital I/O pins (SCL, SDA, ALM, RSTIO)
Vih Input logic high 1.2
VVil Input logic low 0.35
Vol Output logic low (SDA, ALM, RSTIO) Iol = 4 mA 0.4
BATD/CD pin
Vith Input threshold voltage 1.46 1.61 1.76
V
Vihyst Input voltage hysteresis 0.1
Voh Output logic high
(charge inhibit mode enable) Ioh = 3 mA Vbat-
0.4
Table 5. Electrical characteristics (2.7 V < VCC < 4.5 V, -20C to 70C) (continued)
Symbol Parameter Conditions Min Typ Max Units
IO
DocID025995 Rev 1 7/28
GG25L Electrical characteristics
28
Figure 2. I²C timing diagram
Table 6. I²C timing - VIO= 2.8 V, Tamb = -20 °C to 70 C (unless otherwise specified)
Symbol Parameter Min Typ Max Unit
Fscl SCL clock frequency 0
-
400 kHz
thd,sta Hold time (repeated) START condition 0.6
µs
tlow LOW period of the SCL clock 1.3
thigh HIGH period of the SCL clock 0.6
tsu,dat Setup time for repeated START condition 0.6
thd,dat Data hold time 0 0.9
tsu,dat Data setup time 100 ns
trRise time of both SDA and SCL signals 20+
0.1Cb
300 ns
tfFall time of both SDA and SCL signals 20+
0.1Cb
300 ns
tsu,sto Setup time for STOP condition 0.6 µs
tbuf
Bus free time between a STOP and
START condition 1.3 µs
CbCapacitive load for each bus line 400 pF
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Application information GG25L
8/28 DocID025995 Rev 1
5 Application information
Figure 3. Example of an application schematic using the GG25L in mixed mode
Figure 4. Example of an application schematic using the GG25L without current
sensing
Table 7. External component list
Name Value Tolerance Comments
Rcg 5 to 50 m1% to 5% Current sense resistor (2% or better recommended)
C1 1 µF Supply decoupling capacitor
C2 220 nF Battery voltage input filter (optional)
R1 1 kBattery voltage input filter (optional)
R2 1 kBattery detection function
IO voltage
Optional filter
GND
Battery pack
Other
detection
circuit
Rcg
Rid
C1 R1
GG25L
R2
SCL
SDA
ALM
RSTIO
VCC
VIN
BATD/CD
CG
C2
IO voltage
Optional filter
GND
Battery pack
Other
detection
circuit
Rid
C1 R1
GG25L
R2
C2
SCL
SDA
ALM
RSTIO
VCC
VIN
BATD/CD
CG
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GG25L Application information
28
Table 8. External component list
Name Value Comments
C1 1 µF Supply decoupling capacitor
C2 220 nF
Battery voltage input filter (optional)
R1 1 k
R2 1 kBattery detection function
Functional description GG25L
10/28 DocID025995 Rev 1
6 Functional description
6.1 Battery monitoring functions
6.1.1 Operating modes
The monitoring functions include the measurement of battery voltage, current, and
temperature. A Coulomb counter is available to track the SOC when the battery is charging
or discharging at a high rate. A sigma-delta A/D converter is used to measure the voltage,
current, and temperature.
The GG25L can operate in two different modes with different power consumption (see
Table 9. Mode selection is made by the VMODE bit in register 0 (refer to Table 14 for
register 0 definition).
In mixed mode, current is measured continuously (except for a conversion cycle every 4 s
and every 16 s seconds for measuring voltage and temperature respectively). This provides
the highest accuracy from the gas gauge.
In voltage mode with no current sensing, a voltage conversion is made every 4 s and a
temperature conversion every 16 s. This mode provides the lowest power consumption.
It is possible to switch between the two operating modes to get the best accuracy during
active periods, and to save power during standby periods while still keeping track of the
SOC information.
6.1.2 Battery voltage monitoring
Battery voltage is measured by using one conversion cycle of the A/D converter every 4 s.
The conversion cycle takes 213 = 8192 clock cycles. Using the 32768 Hz internal clock, the
conversion cycle time is 250 ms.
The voltage range is 0 to 4.5 V and resolution is 2.20 mV. Accuracy of the voltage
measurement is ±0.5% over the temperature range. This allows accurate SOC information
from the battery open-circuit voltage.
The result is stored in the REG_VOLTAGE register (see Table 13).
Table 9. GG25L operating modes
VMODE Description
0 Mixed mode, Coulomb counter is active, voltage gas gauge runs in parallel
1Voltage gas gauge with power saving
Coulomb counter is not used. No current sensing.
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GG25L Functional description
28
6.1.3 Internal temperature monitoring
The chip temperature (close to the battery temperature) is measured using one conversion
cycle of the A/D converter every 16 s.
The conversion cycle takes 213 = 8192 clock cycles. Using the 32768 Hz internal clock, the
conversion cycle time is 250 ms. Resolution is 1° C and range is -40 to +125 °C.
The result is stored in the REG_TEMPERATURE register (see Table 13).
6.1.4 Current sensing
Voltage drop across the sense resistor is integrated during a conversion period and input to
the 14-bit sigma-delta A/D converter.
Using the 32768 Hz internal clock, the conversion cycle time is 500 ms for a 14-bit
resolution. The LSB value is 5.88 µV. The A/D converter output is in two’s complement
format.
When a conversion cycle is completed, the result is added to the Coulomb counter
accumulator and the number of conversions is incremented in a 16-bit counter.
The current register is updated only after the conversion closest to the voltage conversion
(that is: once per 4-s measurement cycle). The result is stored in the REG_CURRENT
register (see Table 13).
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Functional description GG25L
12/28 DocID025995 Rev 1
6.2 GG25L gas gauge architecture
6.2.1 Coulomb counter
The Coulomb counter is used to track the SOC of the battery when the battery is charging or
discharging at a high rate. Each current conversion result is accumulated (Coulomb
counting) for the calculation of the relative SOC value based on the configuration register.
The system controller can control the Coulomb counter and set and read the SOC register
through the I²C control registers.
Figure 5. Coulomb counter block diagram
The REG_CC_CNF value depends on battery capacity and the current sense resistor. It
scales the charge integrated by the sigma delta converter into a percentage value of the
battery capacity. The default value is 395 (corresponding to a 10 m sense resistor and
1957 mAh battery capacity).
The Coulomb counter is inactive if the VMODE bit is set, this is the default state at power-
on-reset (POR) or reset (VMODE bit = 1).
Writing a value to the register REG_SOC (mixed mode SOC) forces the Coulomb counter
gas gauge algorithm to restart from this new SOC value.
REG_CC_CNF register is a 16-bit integer value and is calculated as shown in Equation 1:
Equation 1
Rsense is in m and Cnom is in mAh.
Example: Rsense =10 m, Cnom = 1650 mAh, REG_CC_CNF = 333
CC SOC
register (internal)
REG_CURRENT
register
register
REG_COUNTER
16-bit counter
REG_CC_CNF
register
CC SOC
calculator
AD converter
EOC
CG
GND
REG_CC_CNF Rsense Cnom49.556=
DocID025995 Rev 1 13/28
GG25L Functional description
28
6.2.2 Voltage gas gauge algorithm
No current sensing is needed for the voltage gas gauge. An internal algorithm precisely
simulates the dynamic behavior of the battery and provides an estimation of the OCV. The
battery SOC is related to the OCV by means of a high-precision reference OCV curve built
into the GG25L.
Any change in battery voltage causes the algorithm to track both the OCV and SOC values,
taking into account the non-linear characteristics and time constants related to the chemical
nature of the Li-Ion and Li-Po batteries.
A single parameter fits the algorithm to a specific battery. The default value provides good
results for most battery chemistries used in hand-held applications.
Figure 6. Voltage gas gauge block diagram
Voltage gas gauge algorithm registers
The REG_VM_CNF configuration register is used to configure the parameter used by the
algorithm based on battery characteristic. The default value is 321.
The REG_OCV register holds the estimated OCV value corresponding to the present
battery state.
The REG_OCVTAB registers are used to adjust the internal OCV table to a given battery
type.
The REG_VM_CNF register is a 12-bit integer value and is calculated from the averaged
internal resistance and nominal capacity of the battery as shown in Equation 2:
Equation 2
Ri is in m and Cnom is in mAh.
Example: Ri = 190 m, Cnom =1650 mAh, REG_VM_CNF = 321
Voltage mode
algorithm
OCV adjustment registers
Voltage register
VM configuration
To SO C
management
OCV value
(VM)
Reference
OCV
curve
AD
converter
VIN
REG_VM_CNF Ri Cnom977.78=
II
Functional description GG25L
14/28 DocID025995 Rev 1
6.2.3 Mixed mode gas gauge system
The GG25L provides a mixed mode gas gauge using both a Coulomb counter (CC) and a
voltage-mode (VM) algorithm to track the SOC of the battery in all conditions with optimum
accuracy. The GG25L directly provides the SOC information.
The Coulomb counter is mainly used when the battery is charging or discharging at a high
rate. Each current conversion result is accumulated (Coulomb counting) for the calculation
of the relative SOC value based on a configuration register.
The voltage-mode algorithm is used when the application is in low power consumption state.
The GG25L automatically uses the best method in any given application condition.
However, when the application enters standby mode, the GG25L can be put in power-
saving mode: only the voltage-mode gas gauge stays active, the Coulomb counter is
stopped and power consumption is reduced.
Figure 7. Mixed mode gas gauge block diagram
The combination of the CC and VM algorithms provides optimum accuracy under all
application conditions. The voltage gas gauge cancels any long-term errors and prevents
the SOC drift problem that is commonly found in Coulomb counter only solutions.
Furthermore, the results of the two algorithms are continuously compared and adjustment
factors are calculated. This enables the application to track the CC and VM algorithm
parameters for long-term accuracy, automatically compensating for battery aging,
application condition changes, and temperature effects. Five registers are dedicated to this
monitoring:
REG_CC_ADJ and REG_VM_ADJ are continuously updated. They are signed, 16-bit,
user-adjusted registers with LSB = 1/512 %.
ACC_CC_ADJ and ACC_VM_ADJ are updated only when a method switch occurs.
They are signed, 16-bit user adjusted accumulators with LSB = 1/512%
RST_ACC_CC_ADJ and RST_ACC_VM_ADJ bits in the REG_MODE register are
used to clear the associated counter.
Voltage mode
(VM)
REG_SOC
register
Alarm
management
Parameter
tracking
Coulomb
counter
REG_VM_ADJ
register
REG_CC_ADJ
register
gas gauge
(CC)
SOC
management
DocID025995 Rev 1 15/28
GG25L Functional description
28
6.3 Low battery alarm
The ALM pin provides an alarm signal in case of a low battery condition. The output is an
open drain and an external pull-up resistor is needed in the application. Writing the
IO0DATA bit to 0 forces the ALM output low; writing the IO0DATA bit to 1 lets the ALM
output reflect the battery condition. Reading the IO0DATA bit gives the state of the ALM pin.
When the IO0DATA bit is 1, the ALM pin is driven low if either of the following two conditions
is met:
The battery SOC estimation from the mixed algorithm is less than the programmed
threshold (if the alarm function is enabled by the ALM_ENA bit).
The battery voltage is less than the programmed low voltage level (if the ALM_ENA bit
is set).
When a low-voltage or low-SOC condition is triggered, the GG25L drives the ALM pin low
and sets the ALM_VOLT or ALM_SOC bit in REG_CTRL.
The ALM pin remains low (even if the conditions disappear) until the software writes the
ALM_VOLT and ALM_SOC bits to 0 to clear the interrupt.
Clearing the ALM_VOLT or ALM_SOC while the corresponding low-voltage or low-SOC
condition is still in progress does not generate another interrupt; this condition must
disappear first and must be detected again before another interrupt (ALM pin driven low) is
generated for this alarm. Another alarm condition, if not yet triggered, can still generate an
interrupt.
Usually, the low-SOC alarm occurs first to warn the application of a low battery condition,
then if no action is taken and the battery discharges further, the low-voltage alarm signals a
nearly-empty battery condition.
At power-up, or when the GG25L is reset, the SOC and voltage alarms are enabled
(ALM_ENA bit = 1). The ALM pin is high-impedance directly after POR and is driven low if
the SOC and/or the voltage is below the default thresholds (1% SOC, 3.00 V voltage), after
the first OCV measurement and SOC estimation.
The REG_SOC_ALM register holds the relative SOC alarm level in 0.5 % units (0 to 100 %).
Default value is 2 (i.e. 1% SOC).
The REG_ALARM_VOLTAGE holds the low voltage threshold and can be programmed over
the full scale voltage range with 17.60 (2.20 * 8) mV steps. The default value is 170 (3.00 V).
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Functional description GG25L
16/28 DocID025995 Rev 1
6.4 Power-up and battery swap detection
When the GG25L is powered up at first battery insertion, an automatic battery voltage
measurement cycle is made immediately after startup and debounce delay.
This feature enables the system controller to get the SOC of a newly inserted battery based
on the OCV measured just before the system actually starts.
Figure 8. Timing diagram at power-up
A battery swap is detected when the battery voltage drops below the undervoltage lockout
(UVLO) for more than 1 s. The GG25L restarts when the voltage goes back above UVLO, in
the same way as for a power-up sequence.
Such filtering provides robust battery swap detection and prevents restarting in case of short
voltage drops. This feature protects the application against high surge currents at low
temperatures.
Figure 9. Restart in case of battery swap
Example: When BATD/CD is high (voltage above the 1.61 V threshold) for more than 1 s, a
battery swap is detected. The GG25L restarts when the BATD/CD level returns below the
threshold, in the same way as for a power-up sequence.
Using the 1-s filter prevents false battery swap detection if short contact bouncing occurs at
the battery terminals due to mechanical vibrations or shocks.
VCC UVLO
Short UVLO
event < 1s
No restart,
No operation
interuption
<1s
Long battery disconnection
events > 1s
GG25L restarts
>1s
POR
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DocID025995 Rev 1 17/28
GG25L Functional description
28
6.5 Improving accuracy of the initial OCV measurement with the
advanced functions of BATD/CD and RSTIO pins
The advanced functions of the BATD/CD and RSTIO pins provide a way to ensure that the
OCV measurement at power-up is not affected by the application startup or by the charger
operation. This occurs as follows:
The BATD/CD pin is driven high to VCC voltage which inhibits the charge function
(assuming that the BATD/CD signal is connected to disable input of the charger circuit).
The RSTIO pin senses the system reset state and if the system reset is active (that is
RSTIO is low), the RSTIO is kept low until the end of the OCV measurement.
Figure 10 describes the BATD/CD and RSTIO operation at power-up. Please refer to the
block diagram of Figure 11 for the RSTI, RSTO, BATD_comp_out, and BATD_drive_high
signals.
At the end of the OCV measurement, the BATD/CD and RSTIO pin are released (high
impedance), the application can start and the charger is enabled.
Figure 10. BATD and RSTIO timing diagram at power-up
6.5.1 BATD and RSTIO pins
The GG25L provides platform synchronization signals to provide reliable SOC information in
different cases.
The BATD/CD pin senses the presence of the battery independently of the battery voltage
and it controls the battery charger to inhibit the charge during the initial OCV measurement.
The RSTIO pin can be used to delay the platform startup during the first OCV measurement
at battery insertion.
VCC UVLO
BATD_comp_out
RSTI
POR
Voltage
measurement
1.61V
delay
RST0
Voltage
register
SOC register
BATD_drive_high
OCV
meas.
Application can start,
charge is enabled
SOC
calc.
Functional description GG25L
18/28 DocID025995 Rev 1
Figure 11. BATD and RSTIO
The BATD/CD pin used as a battery detector is an analog I/O.The input detection threshold
is typically 1.61 V.
BATD/CD is also an output connected to VCC level when active. Otherwise, it is high
impedance.
The RSTIO signal is used to control the application system reset during the initial OCV
measurement. The RSTIO pin is a standard I/O pin with open drain output.
BATD/CD can be connected to the NTC sensor or to the identification resistor of the battery
pack. The GG25L does not provide any biasing voltage or current for the battery detection.
An external pull-up resistor or another device has to pull the BATD/CD pin high when the
battery is removed.
Figure 12. BATD/CD pin connection when used as battery detector
BATD/CD
RSTIO
VCC
BATD_drive_high
BATD_comp_out
RSTI
RSTO
1.61 V
+
-
GG25L GG25L Other biasing
and/or detection
circuit
Battery
pack
BATD/CD
Rid
BATD biasing by external circuitryBATD resistor biasing
Battery pack
Rid
Ru (>1 M)
1K 1K
BATD/CD
DocID025995 Rev 1 19/28
GG25L I²C interface
28
7 I²C interface
7.1 Read and write operations
The I²C interface is used to control and read the current accumulator and registers. It is
compatible with the Philips I²C Bus® (version 2.1). It is a slave serial interface with a serial
data line (SDA) and a serial clock line (SCL).
SCL: input clock used to shift data
SDA: input/output bidirectional data transfers
A filter rejects the potential spikes on the bus data line to preserve data integrity.
The bidirectional data line supports transfers up to 400 Kbit/s (fast mode). The data are
shifted to and from the chip on the SDA line, MSB first.
The first bit must be high (START) followed by the 7-bit device address and the read/write
control bit. Bits DevADDR0 to DevADDR2 are factory-programmable, the default device
address value being 1110 000 (AddrID0 = AddrID1 = AddrID2 = 0). The GG25L then sends
an acknowledge at the end of an 8-bit long sequence. The next eight bits correspond to the
register address followed by another acknowledge.
The data field is the last 8-bit long sequence sent, followed by a last acknowledge.
Table 10. Device address format
bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
1110DevADDR2 DevADDR1 DevADDR0 R/W
Table 11. Register address format
bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
RegADDR7 RegADDR6 RegADDR5 RegADDR4 RegADDR3 RegADDR2 RegADDR1 RegADDR0
Table 12. Register data format
bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
DATA7 DATA6 DATA5 DATA4 DATA3 DATA2 DATA1 DATA0
I²C interface GG25L
20/28 DocID025995 Rev 1
Figure 13. Read operation
Figure 14. Write operation
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GG25L I²C interface
28
7.2 Register map
7.2.1 Register map
The register space provides 28 control registers, 1 read-only register for device ID, 16
read/write RAM working registers reserved for the gas gauge algorithm, and 16 OCV
adjustment registers. Mapping of all registers is shown in Table 13. Detailed descriptions of
registers 0 (REG_MODE) and 1 (REG_CTRL) are shown in Table 14 and Table 15. All
registers are reset to default values at power-on or reset, and the PORDET bit in register
REG_CTRL is used to indicate the occurrence of a power-on reset.
Table 13. Register map
Name Address
(decimal) Type POR Soft
POR Description LSB
Control registers 0 to 23
REG_MODE 0 R/W Mode register
REG_CTRL 1 R/W Control and status register
REG_SOC 2-3 R/W Gas gauge relative SOC 1/512%
REG_COUNTER 4-5 R 0x00 0x00 Number of conversions
(2 bytes)
REG_CURRENT 6-7 R 0x00 0x00 Battery current value
(2 bytes) 5.88 µV
REG_VOLTAGE 8-9 R 0x00 0x00 Battery voltage value
(2 bytes) 2.2 mV
REG_TEMPERATURE 10 R 0x00 0x00 Temperature data 1 °C
REG_CC_ADJ_HIGH 11 R/W 0x00 0x00 Coulomb counter adjustment
factor
1/2%
REG_VM_ADJ_HIGH 12 R/W 0x00 0x00 Voltage mode adjustment
factor
REG_OCV 13-14 R/W 0x00 0x00 OCV register (2 bytes) 0.55 mV
REG_CC_CNF 15-16 R/W 395 395 Coulomb counter gas gauge
configuration
REG_VM_CNF 17-18 R/W 321 321 Voltage gas gauge algorithm
parameter
REG_ALARM_SOC 19 R/W 0x02 0x02 SOC alarm level
(default = 1%) 1/2%
REG_ALARM_VOLTAGE 20 R/W 0xAA 0xAA Battery low voltage alarm
level (default is 3 V) 17.6 mV
REG_CURRENT_THRES 21 R/W 0x0A 0x0A Current threshold for the
relaxation counter 47.04 µV
REG_RELAX_COUNT 22 R 0x78 0x78 Relaxation counter
REG_RELAX_MAX 23 R/W 0x78 0x78 Relaxation counter max
value
REG_ID 24 R 0x14 0x14 Part type ID = 14h
I²C interface GG25L
22/28 DocID025995 Rev 1
REG_CC_ADJ_LOW 25 R/W 0x00 0x00 Coulomb counter adjustment
factor
1/512%
REG_VM_ADJ_LOW 26 R/W 0x00 0x00 Voltage mode adjustment
factor
ACC_CC_ADJ 27-28 R/W 0x00 0x00 Coulomb Counter correction
accumulator
ACC_VM_ADJ 29-30 R/W 0x00 0x00 Voltage mode correction
accumulator
RAM registers 32 to 47
REG_RAM0 32 R/W Random Unchanged Working register 0 for gas
gauge
... ... ...
REG_RAM15 47 R/W Random Unchanged Working register 15 for gas
gauge
OCV adjustment
registers
REG_OCVTAB 48 to 63 R/W 0x00 0x00 OCV adjustment table
(16 registers) 0.55 mV
Table 13. Register map (continued)
Name Address
(decimal) Type POR Soft
POR Description LSB
DocID025995 Rev 1 23/28
GG25L I²C interface
28
7.2.2 Register description
Values held in consecutive registers (such as the charge value in the REG_SOC register
pair) are stored with high bits in the first register and low bits in the second register. The
registers must be read with a single I²C access to ensure data integrity. It is possible to read
multiple values in one I²C access. All values must be consistent.
The SOC data are coded in binary format and the LSB of the low byte is 1/512 %. The
battery current is coded in 2’s complement format and the LSB value is 5.88 µV. The battery
voltage is coded in 2’s complement format and the LSB value is 2.20 mV. The temperature
is coded in 2’s complement format and the LSB value is 1°C.
Table 14. REG_MODE - address 0
Name Position Type Def. Description
VMODE 0 R/W 1 0: Mixed mode (Coulomb counter active)
1: Power saving voltage mode
CLR_VM_ADJ 1 R/W 0
Write 1 to clear ACC_VM_ADJ and
REG_VM_ADJ.
Auto clear bit if GG_RUN = 1
CLR_CC_ADJ 2 R/W 0 Write 1 to clear ACC_CC_ADJ and REG_CC_ADJ
Auto clear bit if GG_RUN = 1
ALM_ENA 3 R/W 1
Alarm function
0: Disabled
1: Enabled
GG_RUN 4 R/W 0
0: Standby mode. Accumulator and counter
registers are frozen, gas gauge and battery
monitor functions are in standby.
1: Operating mode.
FORCE_CC 5 R/W 0
Forces the mixed mode relaxation timer to switch
to the Coulomb counter mode.
Write 1, self clear to 0
Relaxation counter = 0
FORCE_VM 6 R/W 0
Forces the mixed mode relaxation timer to switch
to voltage gas gauge mode.
Write 1, self clear to 0
Relaxation counter = Relax_max
7 Unused
I²C interface GG25L
24/28 DocID025995 Rev 1
Table 15. REG_CTRL - address 1
Name Position Type Def. Description
IO0DATA 0
RX
ALM pin status
0 = ALM input is low
1 = ALM input is high
W1
ALM pin output drive
0 = ALM is forced low
1 = ALM is driven by the alarm conditions
GG_RST 1 W 0
0: no effect
1: resets the conversion counter
GG_RST is a self-clearing bit.
GG_VM 2 R 0
Voltage mode active
0 = REG_SOC from Coulomb counter mode
1 = REG_SOC from Voltage mode
BATFAIL 3 R/W 0
Battery removal or UVLO detection bit.
Write 0 to clear
(Write 1 is ignored)
PORDET 4
R1
Power on reset (POR) detection bit
0 = no POR event occurred
1 = POR event occurred
W0
Soft reset
0 = release the soft-reset and clear the POR
detection bit,
1 = assert the soft-reset and set the POR detection
bit.
This bit is self clearing.
ALM_SOC 5 R/W 0 Set with a low-SOC condition.
Cleared by writing 0.
ALM_VOLT 6 R/W 0 Set with a low-voltage condition.
Cleared by writing 0.
7 Unused
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DocID025995 Rev 1 25/28
GG25L Package information
28
8 Package information
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK® is an ST trademark.
Figure 15. Flip Chip CSP 1.40 x 2.04 mm package mechanical drawing
1. The terminal A1 on the bump side is identified by a distinguishing feature - for instance, by a circular “clear
area” typically 0.1 mm in diameter and/or a missing bump.
2. The terminal A1, on the back side, is identified by a distinguishing feature - for instance, by a circular “clear
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Package information GG25L
26/28 DocID025995 Rev 1
area” typically 0.2 mm in diameter depending on the die size.
Figure 16. Flip Chip CSP 1.4 x 2.04 mm footprint recommendation
Table 16. Flip Chip CSP 1.4 x 2.04 mm package mechanical data
Symbol
Dimensions
Millimeters Inches
Min. Typ. Max. Min. Typ. Max.
A0.545 0.600 0.655 0.021 0.024 0.026
A1 0.165 0.200 0.235 0.006 0.008 0.009
A2 0.330 0.350 0.370 0.013 0.014 0.015
b 0.220 0.260 0.300 0.009 0.010 0.012
D 1.98 2.01 2.04 0.078 0.079 0.080
D1 1.20 0.047
E 1.34 1.37 1.40 0.053 0.054 0.055
E1 0.800 0.031
e 0.360 0.400 0.440 0.014 0.016 0.017
fD 0.395 0.405 0.415 0.016 0.016 0.016
fE 0.275 0.285 0.295 0.011 0.011 0.012
G 0.050 0.002
ccc 0.050 0.002
DocID025995 Rev 1 27/28
GG25L Revision history
28
9 Revision history
Table 17. Document revision history
Date Revision Changes
28-Feb-2014 1 Initial release
GG25L
28/28 DocID025995 Rev 1
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