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ADXL356-57 Datasheet

Analog Devices Inc.

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Datasheet

Low Noise, Low Drift, Low Power,
3-Axis MEMS Accelerometers
Data Sheet
ADXL356/ADXL357
Rev. 0 Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2017 Analog Devices, Inc. All rights reserved.
Technical Support www.analog.com
FEATURES
Hermetic package offers excellent long-term stability
0 g offset vs. temperature (all axes): 0.75 mg/°C maximum
Ultralow noise density (all axes): 80 µg/√Hz
Low power, VSUPPLY (LDO enabled)
ADXL356 in measurement mode: 150 µA
ADXL357 in measurement mode: 200 µA
ADXL356/ADXL357 in standby mode: 21 µA
ADXL356 has user adjustable analog output bandwidth
ADXL357 digital output features
Digital serial peripheral interface (SPI)/limited I2C
interfaces supported
20-bit analog-to-digital converter (ADC)
Data interpolation routine for synchronous sampling
Programmable high- and low-pass digital filters
Integrated temperature sensor
Voltage range options
VSUPPLY with internal regulators: 2.25 V to 3.6 V
V1P8ANA, V1P8DIG with internal low dropout (LDO) regulator
bypassed: 1.8 V typical ± 10%
Operating temperature range: 40°C to +125°C
14-terminal, 6 mm × 5.6 mm × 2.05 mm, LCC package, 0.26 g
APPLICATIONS
Inertial measurement units (IMUs)/altitude and heading
reference systems (AHRSs)
Platform stabilization systems
Structural health monitoring
Seismic imaging
Tilt sensing
Robotics
Condition monitoring
FUNCTIONAL BLOCK DIAGRAMS
Figure 1. ADXL356
Figure 2. ADXL357
GENERAL DESCRIPTION
The analog output ADXL356 and the digital output ADXL357
are low noise density, low 0 g offset drift, low power, 3-axis
accelerometers with selectable measurement ranges. The
ADXL356B supports the ±10 g and ±20 g ranges, the
ADXL356C supports the ±10 g and ±40 g ranges, and the
ADXL357 supports the ±10.24 g, ±20.48 g, and ±40.96 g ranges.
The ADXL356/ADXL357 offer industry leading noise, minimal
offset drift over temperature, and long-term stability, enabling
precision applications with minimal calibration.
The low drift, low noise, and low power ADXL357 enables
accurate tilt measurement in an environment with high
vibration, such as airborne IMUs. The low noise of the
ADXL356 over higher frequencies is ideal for wireless condition
monitoring.
The ADXL357 multifunction pin names may be referenced only
by their relevant function for either the SPI or limited I2C
interface.
1 Protected by U.S. Patents 8,472,270; 9,041,462; 8,665,627; 8,917,099; 6,892,576; 9,297,825; and 7,956,621.
TEMP
Z
OUT
Y
OUT
X
OUT
V
SUPPLY
V
SSIO
V
SS
ST1
ST2
ADXL356 STBY
V
DDIO
CONTROL
LOGIC
RANGE
TEMP
SENSOR
POWER
MANAGEMENT
ANALOG
FILTER
X
Y
Z
3-AXIS
SENSOR
V
1P8ANA
LDO
V
1P8DIG
LDO
15429-001
ADC
ADC
ADC
ADC
TEMP
SENSOR
V
1P8ANA
DIGITAL
FILTER
FIFO
POWER
MANAGEMENT
VSUPPLY
V
DDIO
LDO
V
1P8DIG
LDO
X
Y
Z
ANALOG
FILTER
3-AXIS
SENSOR SCLK/VSSIO
MOSI/SDA
MISO/ASEL
VSSIO VSS
INT1
INT2
CS/SCL
ADXL357
DRDY
SERIAL
I/O
CONTROL
LOGIC
15429-002
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 2 of 42
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagrams ............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Analog Output for the ADXL356 ............................................... 3
Digital Output for the ADXL357................................................ 4
SPI Digital Interface Characteristics for the ADXL357........... 6
I2C Digital Interface Characteristics for the ADXL357 ........... 7
Absolute Maximum Ratings ............................................................ 8
Thermal Resistance ...................................................................... 8
Recommended Soldering Profile ............................................... 8
ESD Caution .................................................................................. 8
Pin Configurations and Function Descriptions ........................... 9
Typical Performance Characteristics ........................................... 11
Root Allan Variance (RAV) ADXL357 Characteristics ......... 19
Theory of Operation ...................................................................... 20
Applications Information .............................................................. 21
Analog Output ............................................................................ 21
Digital Output ............................................................................. 21
Axes of Acceleration Sensitivity ............................................... 22
Power Sequencing ...................................................................... 22
Power Supply Description ......................................................... 22
Overrange Protection ................................................................. 22
Self Test ........................................................................................ 22
Filter ............................................................................................. 23
Serial Communications ................................................................. 25
SPI Protocol ................................................................................. 25
I2C Protocol ................................................................................. 26
Reading Acceleration or Temperature Data from the Interface
....................................................................................................... 26
FIFO ................................................................................................. 28
Interrupts ......................................................................................... 29
DATA_RDY ................................................................................. 29
DRDY Pin .................................................................................... 29
FIFO_FULL ................................................................................. 29
FIFO_OVR .................................................................................. 29
Activity ......................................................................................... 29
External Synchronization and Interpolation .......................... 29
ADXL357 Register Map ................................................................. 32
Register Definitions........................................................................ 33
Analog Devices ID Register ...................................................... 33
Analog Devices MEMS ID Register ......................................... 33
Device ID Register ..................................................................... 33
Product Revision ID Register ................................................... 33
Status Register ............................................................................. 33
FIFO Entries Register ................................................................ 34
Temperature Data Registers ...................................................... 34
X-Axis Data Registers ................................................................ 34
Y-Axis Data Registers ................................................................ 35
Z-Axis Data Registers ................................................................ 35
FIFO Access Register ................................................................. 36
X-Axis Offset Trim Registers .................................................... 36
Y-Axis Offset Trim Registers .................................................... 36
Z-Axis Offset Trim Registers .................................................... 37
Activity Enable Register ............................................................ 37
Activity Threshold Registers ..................................................... 37
Activity Count Register ............................................................. 37
Filter Settings Register ............................................................... 38
FIFO Samples Register .............................................................. 38
Interrupt Pin (INTx) Function Map Register ........................ 38
Data Synchronization ................................................................ 39
I2C Speed, Interrupt Polarity, and Range Register ................. 39
Power Control Register.............................................................. 39
Self Test Register ......................................................................... 40
Reset Register .............................................................................. 40
PCB Footprint Pattern ................................................................... 41
Outline Dimensions ....................................................................... 42
Ordering Guide .......................................................................... 42
REVISION HISTORY
2/2017Revision 0: Initial Version
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 3 of 42
SPECIFICATIONS
ANALOG OUTPUT FOR THE ADXL356
TA = 25°C, VSUPPLY = 3.3 V, x-axis acceleration and y-axis acceleration = 0 g, z-axis acceleration = 1 g, and full-scale range = ±10 g, unless
otherwise noted.
Table 1.
Parameter Test Conditions/Comments Min Typ Max Unit
SENSOR INPUT Each axis
Output Full-Scale Range (FSR) ADXL356B, supports two ranges ±1020 g
ADXL356C, supports two ranges ±1040 g
Resonant Frequency1 5.5 kHz
Nonlinearity ±10 g 0.1 %
Cross Axis Sensitivity 1 %
SENSITIVITY Ratiometric to V1P8ANA
Sensitivity at XOUT, YOUT, ZOUT ±10 g 73.6 80 86.4 mV/g
±20 g 36.8 40 43.2 mV/g
±40 g 18.4 20 21.6 mV/g
Sensitivity Change due to Temperature TA = −40°C to +125°C ±0.01 %/°C
0 g OFFSET Each axis, ±10 g
0 g Output for XOUT, YOUT, ZOUT Referred to V1P8ANA/2 −375 ±125 +375 mg
0 g Offset vs. Temperature (X-Axis, Y-Axis, and Z-Axis)2 TA = −40°C to +125°C −0.75 ±0.5 +0.75 mg/°C
Vibration Rectification Error (VRE)3 Offset due to 7.5 g rms vibration,
±10 g range, in a 1 g orientation
<0.1 g
NOISE DENSITY ±10 g
X-Axis, Y-Axis, and Z-Axis 80 µg/√Hz
Velocity Random Walk X-axis and y-axis 45 µm/sec/Hr
Z-axis 65 µm/sec/Hr
BANDWIDTH
Internal Low-Pass Filter Frequency Fixed frequency, 50% response
attenuation
1500 Hz
SELF TEST
Output Change
Z-Axis ±10 g range 1.25 g
POWER SUPPLY
Voltage Range
VSUPPLY4 2.25 2.5 3.6 V
VDDIO V1P8DIG 2.5 3.6 V
V1P8ANA, V1P8DIG with Internal Low Dropout
Regulator (LDO) Bypassed
VSUPPLY = 0 V 1.62 1.8 1.98 V
Current
Measurement Mode
VSUPPLY (LDO Enabled) 150 µA
V1P8ANA (LDO Disabled) 138 µA
V1P8DIG (LDO Disabled) 12 µA
Standby Mode
VSUPPLY (LDO Enabled) 21 µA
V1P8ANA (LDO Disabled) 7 µA
V1P8DIG (LDO Disabled) 10 µA
Turn On Time5 10 g range <10 ms
Power-off to standby <10 ms
OUTPUT AMPLIFIER
Swing No load 0.03 V1P8ANA
0.03
V
Output Series Resistance 32
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 4 of 42
Parameter Test Conditions/Comments Min Typ Max Unit
TEMPERATURE SENSOR
Output at 25°C 892.2 mV
Scale Factor 3.0 mV/°C
TEMPERATURE
Operating Temperature Range −40 +125 °C
1 The resonant frequency is a sensor characteristic. An integrated analog 1.5 kHz (−6 dB) sinc low-pass filter that cannot be bypassed limits the actual output response.
2 The temperature change is −40°C to +25°C or +2C to +12C.
3 The VRE measurement is the shift in dc offset while the device is subject to 12.5 g rms of random vibration from 50 Hz to 2 kHz. The device under test (DUT) is
configured for the ±10 g range and an output data rate of 4 kHz. The VRE scales with the range setting.
4 When V1P8ANA and V1P8DIG are generated internally, VSUPPLY is valid. To disable the LDO and drive V1P8ANA and V1P8DIG externally, connect VSUPPLY to VSS.
5 Standby to measurement mode; valid when the output is within 5 mg of the final value.
DIGITAL OUTPUT FOR THE ADXL357
TA = 25°C, VSUPPLY = 3.3 V, x-axis acceleration and y-axis acceleration = 0 g, z-axis acceleration = 1 g, full-scale range = ±10.24 g, and
output data rate (ODR) = 500 Hz, unless otherwise noted. Note that multifunction pin names may be referenced only by their relevant
function.
Table 2.
Parameter Test Conditions/Comments Min Typ Max Unit
SENSOR INPUT Each axis
Output Full Scale Range (FSR) User selectable ±10.24 g
±20.48 g
±40.96 g
Nonlinearity ±10 g 0.1 % FSR
Cross Axis Sensitivity 1 %
SENSITIVITY Each axis
X-Axis, Y-Axis, and Z-Axis Sensitivity ±10 g 47,104 51,200 55,296 LSB/g
±20 g 23,552 25,600 27,648 LSB/g
±40 g 11,776 12,800 13,824 LSB/g
X-Axis, Y-Axis, and Z-Axis Scale Factor ±10 g 19.5 µg/LSB
±20 g 39 µg/LSB
±40 g 78 µg/LSB
Sensitivity Change due to Temperature TA = −40°C to +125°C ±0.01 %/°C
0 g OFFSET Each axis, ±10 g
X-Axis, Y-Axis, and Z-Axis 0 g Output −375 ±125 +375 mg
0 g Offset vs. Temperature (X-Axis, Y-Axis, and Z-Axis)1 −0.75 ±0.50 +0.75 mg/°C
Vibration Rectification Error (VRE) 2
TA = −40°C to +125°C
Offset due to 7.5 g rms vibration,
±10 g range, in a 1 g orientation
<0.1 g
NOISE DENSITY ±10 g
X-Axis, Y-Axis, and Z-Axis 80 µg/√Hz
Velocity Random Walk X-axis and y-axis 45 µm/sec/Hr
Z-axis 65 µm/sec/Hr
OUTPUT DATA RATE AND BANDWIDTH
ADC Resolution 20 bits
Low-Pass Filter Passband Frequency User programmable, Register 0x28 1 1000 Hz
High-Pass Filter Passband Frequency When Enabled
(Disabled by Default)
User programmable, Register 0x28
for 4 kHz ODR
0.0095 10 Hz
SELF TEST
Output Change
Z-Axis ±10 g range 1.25 g
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 5 of 42
Parameter Test Conditions/Comments Min Typ Max Unit
POWER SUPPLY
Voltage Range
VSUPPLY Operating3 2.25 2.5 3.6 V
VDDIO V1P8DIG 2.5 3.6 V
V1P8ANA and V1P8DIG with Internal LDO Bypassed VSUPPLY = 0 V 1.62 1.8 1.98 V
Current
Measurement Mode
VSUPPLY (LDO Enabled) 200 µA
V
1P8ANA
(LDO Disabled) 160 µA
V1P8DIG (LDO Disabled) 35.5 µA
Standby Mode
VSUPPLY (LDO Enabled) 21 µA
V1P8ANA (LDO Disabled) 7 µA
V1P8DIG (LDO Disabled) 10 µA
Turn On Time4 ±10 g range <10 ms
Power-off to standby <10 ms
TEMPERATURE SENSOR
Output at 25°C 1852 LSB
Scale Factor −9.05 LSB/°C
TEMPERATURE
Operating Temperature Range −40 +125 °C
1 The temperature change is −40°C to +25°C or +25°C to +125°C.
2 The VRE measurement is the shift in dc offset while the device is subject to 12.5 g rms random vibration from 50 Hz to 2 kHz. The DUT is configured for the ±2 g range
and an output data rate of 4 kHz. The VRE scales with the range setting.
3 When V1P8ANA and V1P8DIG are generated internally, VSUPPLY is valid. To disable the LDO and drive V1P8ANA and V1P8DIG externally, connect VSUPPLY to VSS.
4 Standby to measurement mode; valid when the output is within 1 mg of final value.
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 6 of 42
SPI DIGITAL INTERFACE CHARACTERISTICS FOR THE ADXL357
Note that multifunction pin names may be referenced by their relevant function only.
Table 3.
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
DC INPUT LEVELS
Input Voltage
Low Level VIL 0.3 × VDDIO V
High Level V
IH
0.7 × V
DDIO
V
Input Current
Low Level IIL VIN = 0 V −0.1 µA
High Level IIH VIN = VDDIO 0.1 µA
DC OUTPUT LEVELS
Output Voltage
Low Level VOL IOL = IOL, MIN 0.2 × VDDIO V
High Level VOH IOH = IOH, MAX 0.8 × VDDIO V
Output Current
Low Level I
OL
V
= V
−10 mA
High Level IOH VOH = VOH, MIN 4 mA
AC INPUT LEVELS
SCLK Frequency 0.1 10 MHz
SCLK High Time tHIGH 40 ns
SCLK Low Time tLOW 40 ns
CS Setup Time tCSS 20 ns
CS Hold Time tCSH 20 ns
CS Disable Time tCSD 40 ns
Rising SCLK Setup Time tSCLKS 20 ns
MOSI Setup Time tSU 20 ns
MOSI Hold Time tHD 20 ns
AC OUTPUT LEVELS
Propagation Delay tP CLOAD = 30 pF 30 ns
Enable MISO Time tEN 30 ns
Disable MISO Time tDIS 20 ns
Figure 3. SPI Interface Timing Diagram
t
SU
t
CSS
t
LOW
t
HIGH
t
CSD
t
CSH
t
SCLKS
t
EN
t
P
t
DIS
CS
SCLK
MISO
MOSI
t
HD
15429-003
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 7 of 42
I2C DIGITAL INTERFACE CHARACTERISTICS FOR THE ADXL357
Note that multifunction pin names may be referenced only by their relevant function.
Table 4.
Test Conditions/ I2C_HS = 0 (Fast Mode) I2C_HS = 1 (High Speed Mode)
Parameter Symbol Comments Min Typ Max Min Typ Max Unit
DC INPUT LEVELS
Input Voltage
Low Level V
IL
0.3 × V
DDIO
0.3 × V
DDIO
V
High Level VIH 0.7 × VDDIO 0.7 × VDDIO V
Hysteresis of Schmitt
Triggered Inputs
VHYS 0.05 × VDDIO 0.1 × VDDIO µA
Input Current IIL 0.1 × VDDIO < VIN <
0.9 × V
DDIO
10 +10 µA
DC OUTPUT LEVELS
Output Voltage IOL = 3 mA
Low Level V
OL1
V
DDIO
> 2 V 0.4 V
VOL2 VDDIO 2 V 0.2 × VDDIO V
Output Current
Low Level IOL VOL = 0.4 V 20 mA
VOL = 0.6 V 6 mA
AC INPUT LEVELS
SCL Frequency 0 1 0 3.4 MHz
SCL High Time tHIGH 260 60 ns
SCL Low Time t
LOW
500 160 ns
Start Setup Time tSUSTA 260 160 ns
Start Hold Time tHDSTA 260 160 ns
SDA Setup Time tSUDAT 50 10 ns
SDA Hold Time tHDDAT 0 0 ns
Stop Setup Time tSUSTO 260 160 ns
Bus Free Time t
BUF
500 ns
SCL Input Rise Time tRCL 120 80 ns
SCL Input Fall Time tFCL 120 80 ns
SDA Input Rise Time tRDA 120 160 ns
SDA Input Fall Time tFDA 120 160 ns
Width of Spikes to
Suppress
tSP Not shown in Figure 4 50 10 ns
AC OUTPUT LEVELS
Propagation Delay CLOAD = 500 pF
Data tVDDAT 97 450 27 135 ns
Acknowledge tVDACK 450 ns
Output Fall Time tF Not shown in Figure 4 20 ×
(VDDIO/5.5)
120 ns
Figure 4. I2C Interface Timing Diagram
t
SUDAT
t
HDDAT
t
HDSTA
t
LOW
t
HIGH
t
BUF
t
SUSTO
t
SUSTA
t
VDACK
SDA
SCL
t
RCL
t
FCL
t
FDA
t
RDA
t
SUSTA
t
VDDAT
t
VDDAT
15429-004
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 8 of 42
ABSOLUTE MAXIMUM RATINGS
Table 5.
Parameter Rating
Acceleration (Any Axis, 0.1 ms) 5000 g
VSUPPLY, VDDIO 5.4 V
V1P8ANA, V1P8DIG Configured as Inputs 1.98 V
ADXL356
Digital Inputs (RANGE, ST1, ST2, STBY) 0.3 V to VDDIO + 0.3 V
Analog Outputs (XOUT, YOUT, ZOUT, TEMP) −0.3 V to V1P8ANA + 0.3 V
ADXL357
Digital Pins (CS/SCL, SCLK/VSSIO,
MOSI/SDA, MISO/ASEL, INT1, INT2,
DRDY)
−0.3 V to VDDIO + 0.3 V
Operating Temperature Range −40°C to +125°C
Storage Temperature Range −55°C to +150°C
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
THERMAL RESISTANCE
Thermal performance is directly linked to printed circuit board
(PCB) design and operating environment. Careful attention to
PCB thermal design is required.
θJA is the natural convection junction to ambient thermal
resistance measured in a one cubic foot sealed enclosure.
Table 6. Thermal Resistance
Package Type θJA Unit
E-14-11 42 °C/W
1 Thermal impedance simulated values are based on a JEDEC 2S2P thermal
test board with four thermal vias. See JEDEC JESD51.
RECOMMENDED SOLDERING PROFILE
Figure 5 and Table 7 provide details about the recommended
soldering profile.
Figure 5. Recommended Soldering Profile
Table 7. Recommended Soldering Profile
Condition
Profile Feature Sn63/Pb37 Pb-Free
Average Ramp Rate from Liquid
Temperature (TL) to Peak
Temperature (TP)
3°C/sec
maximum
3°C/sec
maximum
Preheat
Minimum Temperature
(TSMIN)
100°C 150°C
Maximum Temperature
(TSMAX)
150°C 200°C
Time from TSMIN to TSMAX (tS) 60 sec to
120 sec
60 sec to
180 sec
TSMAX to TL Ramp-Up Rate 3°C/sec
maximum
3°C/sec
maximum
Liquid Temperature (T
L
) 183°C 217°C
Time Maintained Above TL (tL) 60 sec to
150 sec
60 sec to
150 sec
Peak Temperature (TP) 240°C +
0°C/−5°C
260°C +
0°C/−5°C
Time of Actual TP − 5°C (tP) 10 sec to
30 sec
20 sec to
40 sec
Ramp-Down Rate 6°C/sec
maximum
6°C/sec
maximum
Time from 25°C to Peak
Temperature (t25°C TO PEAK)
6 minutes
maximum
8 minutes
maximum
ESD CAUTION
t
P
t
L
t
25°C TO PEAK
t
S
PREHEAT
CRITICAL ZONE
T
L
TO T
P
TEMPERATURE
TIME
RAMP-DOWN
RAMP-UP
T
SMIN
T
SMAX
T
P
T
L
15429-005
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 9 of 42
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
Figure 6. ADXL356 Pin Configuration
Table 8. ADXL356 Pin Function Descriptions
Pin No. Mnemonic Description
1 RANGE Range Selection Pin. Set this pin to ground to select the ±10 g range, or set this pin to VDDIO to select the
±20 g or ±40 g range. This pin is model dependent (see the Ordering Guide section).
2 ST1 Self Test Pin 1. This pin enables self test mode.
3 ST2 Self Test Pin 2. This pin activates the electromechanical self test actuation.
4 TEMP Temperature Sensor Output.
5 VDDIO Digital Interface Supply Voltage.
6 VSSIO Digital Ground.
7 STBY Standby or Measurement Mode Selection Pin. Set this pin to ground to enter standby mode, or set this pin
to VDDIO to enter measurement mode.
8 V1P8DIG Digital Supply. This pin requires a decoupling capacitor. If VSUPPLY connects to VSS, supply the voltage to this
pin externally.
9 VSS Analog Ground.
10 V1P8ANA Analog Supply. This pin requires a decoupling capacitor. If VSUPPLY connects to VSS, supply the voltage to this
pin externally.
11 VSUPPLY Supply Voltage. When VSUPPLY equals 2.25 V to 3.6 V, VSUPPLY enables the internal LDO regulators to generate
V1P8DIG and V1P8ANA. For VSUPPLY = VSS, V1P8DIG and V1P8ANA are externally supplied.
12 XOUT X-Axis Output.
13 YOUT Y-Axis Output.
14 Z
OUT
Z-Axis Output.
ADXL356
TOP VIEW
(Not to Scale)
V
SUPPLY
V
1P8ANA
V
SS
V
1P8DIG
RANGE
ST1
ST2
TEMP
11
10
9
Z
OUT
Y
OUT
X
OUT
14
13
12
8
1
2
3
V
DDIO
V
SSIO
STBY
5
6
7
4
X
Z
Y
15429-006
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 10 of 42
Figure 7. ADXL357 Pin Configuration (SPI/I2C)
Table 9. ADXL357 Pin Function Descriptions
Pin No. Mnemonic Description
1 CS/SCL Chip Select for SPI (CS).
Serial Communications Clock for I2C (SCL).
2 SCLK/VSSIO Serial Communications Clock for SPI (SCLK).
I2C Mode Enable (VSSIO). Connect this pin to Pin 6 (VSSIO) to enable I2C mode.
3 MOSI/SDA Master Output, Slave Input for SPI (MOSI).
Serial Data for I2C (SDA).
4 MISO/ASEL Master Input, Slave Output for SPI (MISO).
Alternate I2C Address Select for I2C (ASEL).
5 VDDIO Digital Interface Supply Voltage.
6 VSSIO Digital Ground.
7 RESERVED Reserved. This pin can be connected to ground or left open.
8 V1P8DIG Digital Supply. This pin requires a decoupling capacitor. If VSUPPLY connects to VSS, supply the voltage to this
pin externally.
9 VSS Analog Ground.
10 V1P8ANA Analog Supply. This pin requires a decoupling capacitor. If VSUPPLY connects to VSS, supply the voltage to this
pin externally.
11 VSUPPLY Supply Voltage. When VSUPPLY equals 2.25 V to 3.6 V, VSUPPLY enables the internal LDOs to generate V1P8DIG and
V1P8ANA. For VSUPPLY = VSS, V1P8DIG and V1P8ANA are externally supplied.
12 INT1 Interrupt Pin 1.
13 INT2 Interrupt Pin 2.
14 DRDY Data Ready Pin.
ADXL357
TOP VIEW
(Not to Scale)
VSUPPLY
X
Z
Y
V1P8ANA
VSS
V1P8DIG
CS/SCL
SCLK/VSSIO
MOSI/SDA
MISO/ASEL
11
10
9
DRDY
INT2
INT1
14
13
12
8
1
2
3
VDDIO
VSSIO
RESERVED
5
6
7
4
15429-007
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 11 of 42
TYPICAL PERFORMANCE CHARACTERISTICS
All figures include data for multiple devices and multiple lots, and they were taken in the ±10 g range, unless otherwise noted.
Figure 8. ADXL356 Frequency Response for X-Axis
Figure 9. ADXL356 Frequency Response for Y-Axis
Figure 10. ADXL356 Frequency Response for Z-Axis
Figure 11. ADXL357 Normalized Frequency Response for X-Axis at 4 kHz ODR
Figure 12. ADXL357 Normalized Frequency Response for Y-Axis at 4 kHz ODR
Figure 13. ADXL357 Normalized Frequency Response for Z-Axis at 4 kHz ODR
10
0.1
1
10 10k1k100
X-AXIS RESPONSE (dB)
FREQUENCY (Hz)
15429-008
10
0.1
1
10 10k1k100
Y-AXIS RESPONSE (dB)
FREQUENCY (Hz)
15429-009
10
0.1
1
10 10k1k100
Z-AXIS RESPONSE (dB)
FREQUENCY (Hz)
15429-010
1
0.01
0.1
10 10k1k100
X-AXIS RESPONSE (dB)
FREQUENCY (Hz)
15429-011
1
0.01
0.1
10 10k1k100
Y-AXIS RESPONSE (dB)
FREQUENCY (Hz)
15429-012
1
0.01
0.1
10 10k1k100
Z-AXIS RESPONSE (dB)
FREQUENCY (Hz)
15429-013
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 12 of 42
Figure 14. ADXL356 X-Axis Zero g Offset Normalized Relative to 25°C vs.
Temperature
Figure 15. ADXL356 Y-Axis Zero g Offset Normalized Relative to 25°C vs.
Temperature
Figure 16. ADXL356 Z-Axis Zero g Offset Normalized Relative to 25°C vs.
Temperature
Figure 17. ADXL356 X-Axis Change in Sensitivity Relative to 25°C vs.
Temperature
Figure 18. ADXL356 Y-Axis Change in Sensitivity Relative to 25°C vs.
Temperature
Figure 19. ADXL356 Z-Axis Change in Sensitivity Relative to 25°C vs.
Temperature
75
–75
–50
–25
0
25
50
–40 –25 –10 520 35 50 65 80 95 110 125
OFFSET NORMALIZED (mg)
TEMPERATURE (°C)
15429-014
75
–75
–50
–25
0
25
50
–40 –25 –10 520 35 50 65 80 95 110 125
OFFSET NORMALIZED (mg)
TEMPERATURE (°C)
15429-015
75
–75
–50
–25
0
25
50
–40 –25 –10 520 35 50 65 80 95 110 125
OFFSET NORMALIZED (mg)
TEMPERATURE (°C)
15429-016
1.0
–1.0
–0.5
0
0.5
–40 –25 –10 520 35 50 65 80 95 110 125
CHANGE IN SENSITIVITY (%)
TEMPERATURE (°C)
15429-017
1.0
–1.0
–0.5
0
0.5
–40 –25 –10 520 35 50 65 80 95 110 125
CHANGE IN SENSITIVITY (%)
TEMPERATURE (°C)
15429-018
1.0
–1.0
–0.5
0
0.5
–40 –25 –10 520 35 50 65 80 95 110 125
CHANGE IN SENSITIVITY (%)
TEMPERATURE (°C)
15429-019
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 13 of 42
Figure 20. ADXL356 Zero g Offset Histogram at 25°C, X-Axis
Figure 21. ADXL356 Zero g Offset Histogram at 25°C, Y-Axis
Figure 22. ADXL356 Zero g Offset Histogram at 25°C, Z-Axis
Figure 23. ADXL356 Sensitivity Histogram at 25°C, X-Axis
Figure 24. ADXL356 Sensitivity Histogram at 25°C, Y-Axis
Figure 25. ADXL356 Sensitivity Histogram at 25°C, Z-Axis
40
0
10
20
30
5
15
25
35
PERCENT OF POPULATION (%)
X-AXIS OFFSET AT 25°C (mg)
–375
–325
–275
–225
–175
–125
–75
–25
25
75
125
175
225
275
325
375
15429-020
30
0
10
20
5
15
25
PERCENT OF POPULATION (%)
Y-AXIS OFFSET AT 25°C (mg)
–375
–325
–275
–225
–175
–125
–75
–25
25
75
125
175
225
275
325
375
15429-021
25
0
10
20
5
15
PERCENT OF POPULATION (%)
Z-AXIS OFFSET AT 25°C (mg)
–375
–325
–275
–225
–175
–125
–75
–25
25
75
125
175
225
275
325
375
15429-022
25
0
10
20
5
15
PERCENT OF POPULATION (%)
X-AXIS OFFSET AT 25°C (V/g)
0.0736
0.0740
0.0744
0.0748
0.0752
0.0756
0.0760
0.0764
0.0768
0.0772
0.0776
0.0780
0.0784
0.0788
0.0792
0.0796
0.0800
0.0804
0.0808
0.0812
0.0816
0.0820
0.0824
0.0828
0.0832
0.0836
0.0840
0.0844
0.0848
0.0852
0.0856
0.0860
0.0864
15429-023
25
0
10
20
5
15
PERCENT OF POPULATION (%)
Y-AXIS OFFSET AT 25°C (V/g)
0.0736
0.0740
0.0744
0.0748
0.0752
0.0756
0.0760
0.0764
0.0768
0.0772
0.0776
0.0780
0.0784
0.0788
0.0792
0.0796
0.0800
0.0804
0.0808
0.0812
0.0816
0.0820
0.0824
0.0828
0.0832
0.0836
0.0840
0.0844
0.0848
0.0852
0.0856
0.0860
0.0864
15429-024
25
0
10
20
5
15
PERCENT OF POPULATION (%)
Z-AXIS OFFSET AT 25°C (V/g)
0.0736
0.0740
0.0744
0.0748
0.0752
0.0756
0.0760
0.0764
0.0768
0.0772
0.0776
0.0780
0.0784
0.0788
0.0792
0.0796
0.0800
0.0804
0.0808
0.0812
0.0816
0.0820
0.0824
0.0828
0.0832
0.0836
0.0840
0.0844
0.0848
0.0852
0.0856
0.0860
0.0864
15429-025
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 14 of 42
Figure 26. ADXL356 Vibration Rectification Error (VRE),
X-Axis Offset from +1 g, ±10 g Range, X-Axis Orientation = −1 g
Figure 27. ADXL356 Vibration Rectification Error (VRE),
Y-Axis Offset from +1 g, ±10 g Range, Y-Axis Orientation = +1 g
Figure 28. ADXL356 Vibration Rectification Error (VRE),
Z-Axis Offset from +1 g, ±10 g Range, Z-Axis Orientation = +1 g
Figure 29. ADXL356 Vibration Rectification Error (VRE),
X-Axis Offset from +1 g, ±40 g Range, X-Axis Orientation = −1 g
Figure 30. ADXL356 Vibration Rectification Error (VRE),
Y-Axis Offset from +1 g, ±40 g Range, Y-Axis Orientation = +1 g
Figure 31. ADXL356 Vibration Rectification Error (VRE),
Z-Axis Offset from +1 g, ±40 g Range, Z-Axis Orientation = +1 g
0.20
–0.20
–0.15
–0.10
–0.05
0
0.05
0.10
0.15
0108642
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-026
0.20
–0.20
–0.15
–0.10
–0.05
0
0.05
0.10
0.15
0108642
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-027
0.20
–0.20
–0.15
–0.10
–0.05
0
0.05
0.10
0.15
0108642
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-028
0.10
–0.10
–0.05
0
0.05
0252015105
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-029
0.2
–0.2
–0.1
0
0.1
0252015105
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-030
0.2
–0.2
–0.1
0
0.1
0252015105
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-031
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 15 of 42
Figure 32. ADXL357 X-Axis Zero g Offset Normalized Relative to 25°C vs.
Temperature
Figure 33. ADXL357 Y-Axis Zero g Offset Normalized Relative to 25°C vs.
Temperature
Figure 34. ADXL357 Z-Axis Zero g Offset Normalized Relative to 25°C vs.
Temperature
Figure 35. ADXL357 X-Axis Change in Sensitivity Relative to 25°C vs.
Temperature
Figure 36. ADXL357 Y-Axis Change in Sensitivity Relative to 25°C vs.
Temperature
Figure 37. ADXL357 Z-Axis Change in Sensitivity Relative to 25°C vs.
Temperature
75
–75
–50
–25
0
25
50
–45 –30 –15 015 30 45 60 75 90 105 120 135
OFFSET NORMALIZED (mg)
TEMPERATURE (°C)
15429-032
75
–75
–50
–25
0
25
50
–45 –25 –5 15 35 55 75 95 115
OFFSET NORMALIZED (mg)
TEMPERATURE (°C)
15429-033
75
–75
–50
–25
0
25
50
–45 –25 –5 15 35 55 75 95 115
OFFSET NORMALIZED (mg)
TEMPERATURE (°C)
15429-034
1.0
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
–40 –25 –10 520 35 50 65 80 95 110 125
CHANGE IN SENSITIVITY (%)
TEMPERATURE (°C)
15429-035
1.0
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
–40 –25 –10 520 35 50 65 80 95 110 125
CHANGE IN SENSITIVITY (%)
TEMPERATURE (°C)
15429-036
1.0
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
–40 –25 –10 520 35 50 65 80 95 110 125
CHANGE IN SENSITIVITY (%)
TEMPERATURE (°C)
15429-037
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 16 of 42
Figure 38. ADXL357 Zero g Offset Histogram at 25°C, X-Axis
Figure 39. ADXL357 Zero g Offset Histogram at 25°C, Y-Axis
Figure 40. ADXL357 Zero g Offset Histogram at 25°C, Z-Axis
Figure 41. ADXL357 Sensitivity Histogram at 25°C, X-Axis
Figure 42. ADXL357 Sensitivity Histogram at 25°C, Y-Axis
Figure 43. ADXL357 Sensitivity Histogram at 25°C, Z-Axis
35
0
10
20
30
5
15
25
PERCENT OF POPULATION (%)
X-AXIS OFFSET AT 25°C (mg)
–375
–325
–275
–225
–175
–125
–75
–25
25
75
125
175
225
275
325
375
15429-038
40
35
0
10
20
30
5
15
25
PERCENT OF POPULATION (%)
Y-AXIS OFFSET AT 25°C (mg)
–375
–325
–275
–225
–175
–125
–75
–25
25
75
125
175
225
275
325
375
15429-039
25
0
10
20
5
15
PERCENT OF POPULATION (%)
Z-AXIS OFFSET AT 25°C (mg)
–375
–325
–275
–225
–175
–125
–75
–25
25
75
125
175
225
275
325
375
15429-040
40
0
10
20
30
5
15
25
35
PERCENT OF POPULATION (%)
X-AXIS SENSITIVITY AT 25°C (LSB/g)
47104
47616
48128
48640
49152
49664
50176
50688
51200
51712
52224
52736
53248
53760
54272
54784
55296
15429-041
45
40
0
10
20
30
5
15
25
35
PERCENT OF POPULATION (%)
Y-AXIS SENSITIVITY AT 25°C (LSB/g)
47104
47616
48128
48640
49152
49664
50176
50688
51200
51712
52224
52736
53248
53760
54272
54784
55296
15429-042
30
0
10
20
5
15
25
PERCENT OF POPULATION (%)
Z-AXIS SENSITIVITY AT 25°C (LSB/g)
47104
47616
48128
48640
49152
49664
50176
50688
51200
51712
52224
52736
53248
53760
54272
54784
55296
15429-043
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 17 of 42
Figure 44. ADXL357 Vibration Rectification Error (VRE),
X-Axis Offset from +1 g, ±10 g Range, X-Axis Orientation = −1 g
Figure 45. ADXL357 Vibration Rectification Error (VRE),
Y-Axis Offset from +1 g, ±10 g Range, Y-Axis Orientation = +1 g
Figure 46. ADXL357 Vibration Rectification Error (VRE),
Z-Axis Offset from +1 g, ±10 g Range, Z-Axis Orientation = +1 g
Figure 47. ADXL357 Vibration Rectification Error (VRE),
X-Axis Offset from +1 g, ±40 g Range, X-Axis Orientation = −1 g
Figure 48. ADXL357 Vibration Rectification Error (VRE),
Y-Axis Offset from +1 g, ±40 g Range, Y-Axis Orientation = +1 g
Figure 49. ADXL357 Vibration Rectification Error (VRE),
Z-Axis Offset from +1 g, ±40 g Range, Z-Axis Orientation = +1 g
0.5
–0.30
–0.25
–0.20
–0.15
–0.10
–0.05
0
0108642
OFFSET CHANGE (g)
INPUT VIBRATION (g rms)
15429-044
0.5
–0.30
–0.25
–0.20
–0.15
–0.10
–0.05
0
0108642
OFFSET CHANGE (g)
INPUT VIBRATION (g rms)
15429-045
0.5
–0.30
–0.25
–0.20
–0.15
–0.10
–0.05
0
0108642
OFFSET CHANGE (g)
INPUT VIBRATION (g rms)
15429-046
0.20
–0.20
–0.15
–0.10
–0.05
0
0.05
0.10
0.15
0252015105
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-047
0.20
–0.20
–0.15
–0.10
–0.05
0
0.05
0.10
0.15
0252015105
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-048
0.20
–0.20
–0.15
–0.10
–0.05
0
0.05
0.10
0.15
0252015105
OFFSET SHIFT (g)
INPUT VIBRATION (g rms)
15429-049
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 18 of 42
Figure 50. ADXL356 Temperature Sensor Output and Linearity Offset vs.
Temperature
Figure 51. ADXL356 Total Supply Current, 3.3 V
Figure 52. ADXL357 Internal ODR Frequency Histogram
Figure 53. ADXL357 Temperature Sensor Output and Linearity Offset vs.
Temperature
Figure 54. ADXL357 Total Supply Current, 3.3 V
–0.0010
–0.0005
0
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030
0.0035
0.7
0.8
0.9
1.0
1.1
1.2
1.3
–40 –20 120100806040200
LINEAR OFFSET (V)
TEMPERATURE SENSOR OUTPUT (V)
TEMPERATURE (°C)
TEMPERATURE SENSOR OUTPUT
LINEAR OFFSET
15429-050
35
30
25
0
10
20
5
15
PERCENT OF POPULATION (%)
TOTAL SUPPLY CURRENT AT 25°C (µA)
125
127
129
131
133
135
137
139
141
143
145
147
149
151
153
155
157
159
161
163
165
167
169
171
175
173
15429-051
35
30
25
0
10
20
5
15
PERCENT OF POPULATION (%)
ODR FREQUENCY (Hz)
3800
3840
3880
3920
3960
4000
4040
4080
4120
4160
4200
15429-052
–6
6
4
2
0
–2
–4
700
900
1100
1300
1500
1700
1900
2100
2300
–40 –20 120100806040200
LINEAR OFFSET (V)
TEMPERATURE SENSOR OUTPUT (LSB)
TEMPERATURE (°C)
TEMPERATURE SENSOR OUTPUT
LINEAR OFFSET
15429-053
30
25
0
10
20
5
15
PERCENT OF POPULATION (%)
TOTAL SUPPLY CURRENT AT 25°C (µA)
175
177
179
181
183
185
187
189
191
193
195
197
199
201
203
205
207
209
211
213
215
217
219
221
223
225
15429-054
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 19 of 42
ROOT ALLAN VARIANCE (RAV) ADXL357 CHARACTERISTICS
Figure 55 to Figure 57 include data for multiple devices and multiple lots, and they were taken in the ±10 g range, unless otherwise noted.
Figure 55. ADXL357 Root Allan Variance (RAV), X-Axis
Figure 56. ADXL357 Root Allan Variance (RAV), Y-Axis
Figure 57. ADXL357 Root Allan Variance (RAV), Z-Axis
1000
1
10
100
0.01 10001001010.1
ROOT ALLAN VARIANCE (µg)
INTEGRATION TIME (Seconds)
15429-055
1000
1
10
100
0.01 10001001010.1
ROOT ALLAN VARIANCE (µg)
INTEGRATION TIME (Seconds)
15429-056
1000
1
10
100
0.01 10001001010.1
ROOT ALLAN VARIANCE (µg)
INTEGRATION TIME (Seconds)
15429-057
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 20 of 42
THEORY OF OPERATION
The ADXL356 is a complete 3-axis, ultralow noise and ultrastable
offset MEMS accelerometer with outputs ratiometric to the analog
1.8 V supply, V1P8ANA. The ADXL357 adds three high resolution
ADCs that use the analog 1.8 V supply as a reference to provide
digital outputs insensitive to the supply voltage. The ADXL356B
is pin selectable for ±10 g or ±20 g full scale, the ADXL356C is pin
selectable for ±10 g or ±40 g full scale, and the ADXL357 is
programmable for ±10.24 g, ±20.48 g, and ±40.96 g full scale.
The ADXL357 offers both SPI and I2C communications ports.
The micromachined, sensing elements are fully differential,
comprising the lateral x-axis and y-axis sensors and the vertical,
teeter totter z-axis sensors. The x-axis and y-axis sensors and
the z-axis sensors go through separate signal paths that minimize
offset drift and noise. The signal path is fully differential, except
for a differential to single-ended conversion at the analog
outputs of the ADXL356.
The analog accelerometer outputs of the ADXL356 are ratiometric
to V1P8ANA; therefore, carefully digitize them correctly. The tempera-
ture sensor output is not ratiometric. The XOUT, YOUT, and ZOUT
analog outputs are filtered internally with an antialiasing filter.
These analog outputs also have an internal 32 kΩ series resistor
that can be used with an external capacitor to set the bandwidth
of the output.
The ADXL357 includes antialias filters before and after the high
resolution Σ-Δ ADC. User-selectable output data rates and filter
corners are provided. The temperature sensor is digitized with a
12-bit successive approximation register (SAR) ADC.
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 21 of 42
APPLICATIONS INFORMATION
ANALOG OUTPUT
Figure 58 shows the ADXL356 application circuit. The analog
outputs (XOUT, YOUT, and ZOUT) are ratiometric to the 1.8 V
analog voltage from the V1P8ANA pin. V1P8ANA can be powered
with an on-chip LDO regulator that is powered from VSUPPLY.
V1P8ANA can also be supplied externally by forcing VSUPPLY to VSS,
which disables the LDO regulator. Due to the ratiometric
response, the analog output requires referencing to the V1P8ANA
supply when digitizing to achieve the inherent noise and offset
performance of the ADXL356. The 0 g bias output is nominally
equal to V1P8ANA/2. The recommended option is to use the
ADXL356 with a ratiometric ADC (for example, the Analog
Devices, Inc., AD7682) with V1P8ANA providing the voltage
reference. This configuration results in self cancellation of
errors due to minor supply variations.
The ADXL356 outputs two forms of filtering: internal anti-
aliasing filtering with a cutoff frequency of approximately 1.5 kHz,
and external filtering. The external filter uses a fixed, on-chip,
32 kΩ resistance in series with each output in conjunction with
the external capacitors to implement the low-pass filter antialiasing
and noise reduction prior to the external ADC. The antialias
filter cutoff frequency must be significantly higher than the
desired signal bandwidth. If the antialias filter corner is too low,
ratiometricity can degrade where the signal attenuation is
different from the reference attenuation.
DIGITAL OUTPUT
Figure 59 shows the ADXL357 application circuit with the
recommended bypass capacitors. The communications interface
is either SPI or I2C (see the Serial Communications section for
additional information).
The ADXL357 includes an internal configurable digital band-
pass filter. Both the high-pass and low-pass poles of the filter
are adjustable, as detailed in the Filter Settings Register section
and Table 44. At power-up, the default conditions for the filters
are as follows:
High-pass filter (HPF) = dc (off)
Low-pass filter (LPF) = 1000 Hz
Output data rate = 4000 Hz
Figure 58. ADXL356 Application Circuit
Figure 59. ADXL357 Application Circuit
ADXL356
VSUPPLY
VDDIO (±20g, ±40g)
GND ( ±10g)
VDDIO (MEASUREMENT)
GND (STANDBY)
V1P8ANA
VSS
V1P8DIG
ADC VREF
RANGE
ST1
ST2
TEMP
11
10
9
ZOUT
YOUT
XOUT
14
13
12
8
1
2
3
VDDIO
VSSIO
STBY
5
6
7
4
2.25V TO 3.6V
1µF0.1µF
1µF0.1µF
1µF
0.1µF
1µF
0.1µF
2.25V TO 3.6V
15429-058
ADXL357
TOP VIEW
(Not to Scale)
V
SUPPLY
V
1P8ANA
V
SS
V
1P8DIG
11
10
9
DRDY
INT2
INT1
14
13
12
8
1
2
3
V
DDIO
V
SSIO
RESERVED
5
6
7
4
2.25V TO 3.6V
1µF0.1µF
1µF0.1µF
1µF
0.1µF
1µF
0.1µF
2.25V TO 3.6V
SPI/I
2
C
INTERFACE
CS/SCL
SCLK/V
SSIO
MOSI/SDA
MISO/ASEL
15429-060
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 22 of 42
AXES OF ACCELERATION SENSITIVITY
Figure 60 shows the axes of acceleration sensitivity. Note that
the output voltage increases when accelerated along the
sensitive axis.
Figure 60. Axes of Acceleration Sensitivity
POWER SEQUENCING
There are two methods for applying power to the device.
Typically, internal LDO regulators generate the 1.8 V power for
the analog and digital supplies, V1P8ANA and V1P8DIG, respectively.
Optionally, connecting VSUPPLY to VSS and driving V1P8ANA and
V1P8DIG with an external supply can supply V1P8ANA and V1P8DIG.
When using the internal LDO regulators, connect VSUPPLY to a
voltage source between 2.25 V to 3.6 V. In this case, VDDIO and
VSUPPLY can be powered in parallel. VSUPPLY must not exceed the
VDDIO voltage by greater than 0.5 V. If necessary, VDDIO can be
powered before VSUPPLY.
When disabling the internal LDO regulators and using an external
1.8 V supply to power V1P8ANA and V1P8DIG, tie VSUPPLY to ground,
and set V1P8ANA and V1P8DIG to the same final voltage level. In the
case of bypassing the LDOs, the recommended power sequence is
to apply power to VDDIO, followed by V1P8DIG approximately 10 µs
later, and then V1P8ANA approximately 10 µs later. If necessary,
V1P8DIG and VDDIO can be powered from the same 1.8 V supply,
which can also be tied to V1P8ANA with proper isolation. In this
case, proper decoupling and low frequency isolation is important
to maintain the noise performance of the sensor.
POWER SUPPLY DESCRIPTION
The ADXL356/ADXL357 have four different power supply
domains: VSUPPLY, V1P8ANA, V1P8DIG, and VDDIO. The internal
analog and digital circuitry operates at 1.8 V nominal.
VSUPPLY
VSUPPLY is 2.25 V to 3.6 V, which is the input range to the two
LDO regulators that generate the nominal 1.8 V outputs for
V1P8ANA and V1P8DIG. Connect VSUP PLY to VSS to disable the LDO
regulators, which allows driving V1P8ANA and V1P8DIG from an
external source.
V1P8ANA
All sensor and analog signal processing circuitry operates in
this domain. Offset and sensitivity of the analog output
ADXL356 are ratiometric to this supply voltage. When using
external ADCs, use V1P8ANA as the reference voltage. The digital
output ADXL357 includes ADCs that are ratiometric to V1P8ANA,
thereby rendering offset and sensitivity insensitive to the value
of V1P8ANA. V1P8ANA can be an input or an output as defined by the
state of the VSUPPLY voltage.
V1P8DIG
V1P8DIG is the supply voltage for the internal logic circuitry. A
separate LDO regulator decouples the digital supply noise from
the analog signal path. V1P8ANA can be an input or an output as
defined by the state of the VSUPPLY voltage. If driven externally,
V1P8DIG must be the same voltage as the V1P8ANA voltage.
VDDIO
The VDDIO value determines the logic high levels. On the analog
output ADXL356, VDDIO sets the logic high level for the self test
pins, ST1 and ST2, as well as the STBY pin. On the digital output
ADXL357, VDDIO sets the logic high level for communications
interface ports, as well as the interrupt and DRDY outputs.
The LDO regulators are operational when VSUPPLY is between
2.25 V and 3.6 V. V1P8ANA and V1P8DIG are the regulator outputs in
this mode. Alternatively, when tying VSUPPLY to VSS, V1P8ANA and
V1P8DIG are supply voltage inputs with a 1.62 V to 1.98 V range.
OVERRANGE PROTECTION
To avoid electrostatic capture of the proof mass when the
accelerometer is subject to input acceleration beyond its full-
scale range, all sensor drive clocks turn off for 0.5 ms. In the
±10 g/±10.24 g range setting, the overrange protection activates
for input signals beyond approximately ±40 g 25%), and for
the ±20 g/±20.48 g and ±40 g/±40.95 g range settings, the
threshold corresponds to about ±80 g 25%).
When overrange protection occurs, the XOUT, YOUT, and ZOUT pins
on the ADXL356 begin to drive to midscale. The ADXL357
floats toward zero, and first in, first out (FIFO) buffer begins
filling with this data.
SELF TEST
The ADXL356 and ADXL357 incorporate a self test feature
that effectively tests the mechanical and electronic system.
Enabling self test stimulates the sensor electrostatically to
produce an output corresponding to the test signal applied as
well as the mechanical force exerted. Only the z-axis response is
specified to validate device functionality.
In the ADXL356, drive the ST1 pin to VDDIO to invoke self test
mode. Then, by driving the ST2 pin to VDDIO, the ADXL356
applies an electrostatic force to the mechanical sensor and
induces a change in output in response to the force. The self test
delta (or response) is the difference in output voltage in the
z-axis when ST2 is high vs. ST2 is low, while ST1 is asserted.
After the self test measurement is complete, bring both pins low
to resume normal operation.
The self test operation is similar in the ADXL357, except ST1
and ST2 can be accessed through the SELF_TEST register
(Register 0x2E).
Y
Z
X
15429-059
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 23 of 42
The self test feature rejects externally applied acceleration and
only responds to the self test force, which allows an accurate
measurement of the self test, even in the presence of external
mechanical noise.
FILTER
The ADXL356/ADXL357 use an analog, low-pass, antialiasing
filter to reduce out of band noise and to limit bandwidth. The
ADXL357 provides further digital filtering options to maintain
excellent noise performance at various ODRs.
The analog, low-pass antialiasing filter in the ADXL356/
ADXL357 provides a fixed bandwidth of approximately
1.5 kHz, the frequency at which the output response is
attenuated by approximately 50%. The shape of the filter
response in the frequency domain is that of a sinc3 filter.
The ADXL356 x-axis, y-axis, and z-axis analog outputs include
an amplifier followed by a series 32 kΩ resistor, and output to
the XOUT, the YOUT, and the ZOUT pins, respectively.
The ADXL357 provides an internal 20-bit, Σ-Δ ADC to digitize
the filtered analog signal. Additional digital filtering (beyond the
analog, low-pass, antialiasing filter) consists of a low-pass digital
decimation filter and a bypassable high-pass filter that supports
output data rates between 4 kHz and 3.906 Hz. The decimation
filter consists of two stages. The first stage is fixed decimation
with a 4 kHz ODR with a low-pass filter cutoff (50% reduction
in output response) at about 1 kHz. A variable second stage
decimation filter is used for the 2 kHz output data rate and below
(it is bypassed for 4 kHz ODR). Figure 61 shows the low-pass
filter response with a 1 kHz corner (4 kHz ODR) for the
ADXL357. Note that Figure 61 does not include the fixed
frequency analog, low-pass, antialiasing filter with a fixed
bandwidth of approximately 1.5 kHz.
Figure 61. ADXL357 Digital Low-Pass Filter (LPF) Response for 4 kHz ODR
The ADXL357 pass band of the signal path relates to the
combined filter responses, including the analog filter previously
described, and the digital decimation filter/ODR setting. Table 10
shows the delay associated with the decimation filter for each
setting and provides the attenuation at the ODR/4 corner.
The ADXL357 also includes an optional digital high-pass filter
with a programmable corner frequency. By default, the high-
pass filter is disabled. The high-pass corner frequency, where
the output is attenuated by 50%, is related to the ODR, and the
HPF_CORNER setting in the filter register (Register 0x28,
Bits[6:4]). Table 11 shows the HPF_CORNER response. Figure 62
and Figure 63 show the simulated high-pass filter response and
delay for a 10 Hz cutoff.
The ADXL357 also includes an interpolation filter, after the
decimation filters, that produces oversampled/upconverted data
and provides an external synchronization option. See the Data
Synchronization section for more details. Table 12 shows the
delay and attenuation relative to the programmed ODR.
Figure 62. High-Pass Filter Pass-Band Response for a 4 kHz ODR and an
HPF_CORNER Setting of 001 (Register 0x28, Bits[6:4])
Group delay is the digital filter delay from the input to the ADC
until data is available at the interface (see the Filter section).
This delay is the largest component of the total delay from
sensor to serial interface.
Figure 63. High-Pass Filter Delay Response for a 4 kHz ODR and an
HPF_CORNER Setting of 001 (Register 0x28, Bits[6:4])
–70
–60
–50
–40
–30
–20
–10
0
110 100 10k1k
DIGITAL LPF RESPONSE (dB)
INPUT FREQUENCY (Hz)
15429-061
AMPLITUDE RELATIVE TO FULL SCALE (dB)
0
–3
–10
–20
–30
–40
–5009.8801 100
FREQUENCY (kHz)
15429-062
DELAY (ODR CYCLES)
40
32.2122
30
20
10
1
009.8801
100
FREQUENCY (kHz)
15429-063
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 24 of 42
Table 10. Digital Filter Group Delay and Profile
Delay Attenuation
Programmed ODR (Hz) ODR (Cycles) Time (ms) Decimator at ODR/4 (dB) Full Path at ODR/4 (dB)
4000 2.52 0.63 3.44 3.63
4000/2 = 2000 2.00 1.00 2.21 2.26
4000/4 = 1000 1.78 1.78 1.92 1.93
4000/8 = 500 1.63 3.26 1.83 1.83
4000/16 = 250 1.57 6.27 1.83 1.83
4000/32 = 125 1.54 12.34 1.83 1.83
4000/64 = 62.5 1.51 24.18 1.83 1.83
4000/128 ~ 31 1.49 47.59 1.83 1.83
4000/256 ~ 16 1.50 96.25 1.83 1.83
4000/512 ~ 8 1.50 189.58 1.83 1.83
4000/1024 ~ 4 1.50 384.31 1.83 1.83
Table 11. Digital High-Pass Filter Response
HPF_CORNER Register Setting
(Register 0x28, Bits[6:4]) HPF_CORNER Frequency, −3 dB Point Relative to ODR Setting −3 dB at 4 kHz ODR (Hz)
000 Not applicable, no high-pass filter enabled Off
001 247 × 10−3 × ODR 9.88
010 62.084 × 10−3 × ODR 2.48
011 15.545 × 10−3 × ODR 0.62
100 3.862 × 10−3 × ODR 0.1545
101 0.954 × 10−3 × ODR 0.03816
110 0.238 × 10−3 × ODR 0.00952
Table 12. Combined Digital Interpolation Filter and Decimation Filter Response
Interpolator Data Rate Resolution
Relative to 64 × ODR (Hz)
Combined Interpolator/
Decimator Delay (ODR Cycles)
Combined Interpolator/
Decimator Delay (ms)
Combined Interpolator/Decimator
Output Attenuation at ODR/4 (dB)
64 × 4000 = 256000 3.51661 0.88 6.18
64 × 2000 = 128000 3.0126 1.51 4.93
64 × 1000 = 64000 2.752 2.75 4.66
64 × 500 = 32000 2.6346 5.27 4.58
64 × 250 = 16000 2.5773 10.31 4.55
64 × 125 = 8000 2.5473 20.38 4.55
64 × 62.5 = 4000 2.53257 40.52 4.55
64 × 31.25 = 2000 2.52452 80.78 4.55
64 × 15.625 = 1000 2.52045 161.31 4.55
64 × 7.8125 = 500 2.5194 322.48 4.55
64 × 3.90625 = 250 2.51714 644.39 4.55
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 25 of 42
SERIAL COMMUNICATIONS
The 4-wire serial interface communicates in either the SPI or
I2C protocol. It affectively autodetects the format being used,
requiring no configuration control to select the format.
SPI PROTOCOL
Wire the ADXL357 for SPI communication as shown in the
connection diagram in Figure 64. The SPI protocol timing is
shown in Figure 65 to Figure 68. The timing scheme follows the
clock polarity (CPOL) = 0 and clock phase (CPHA) = 0. The
SPI clock speed ranges from 100 kHz to 10 MHz.
Figure 64. 4-Wire SPI Connection
Figure 65. SPI Timing DiagramSingle-Byte Read
Figure 66. SPI Timing DiagramSingle-Byte Write
Figure 67. SPI Timing DiagramMultibyte Read
Figure 68. SPI Timing DiagramMultibyte Write
PROCESSOR
CS
MOSI
MISO
SCLK
DOUT
DOUT
DIN
DOUT
ADXL357
15429-064
RWA6 A5 A4 A3 A2 A1 A0
12345678910 11 12 13 14 15 16
CS
SCLK
MOSI
MISO D7 D6 D5 D4 D3 D2 D1 D0
15429-065
D7 D6 D5 D4 D3 D2 D1 D0
12345678910 11 12 13 14 15 16
SCLK
MOSI
MISO
RWA6 A5 A4 A3 A2 A1 A0
CS
15429-066
10 11 12 13 14 15 16 17
123456789
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0D0 D7
BYTE 1 BYTE n
RWA6 A5 A4 A3 A2 A1 A0
SCLK
MOSI
MISO
CS
15429-067
10 11 12 13 14 15 16 17
BYTE 1 BYTE n
123456789
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
D0 D7
RWA6 A5 A4 A3 A2 A1 A0
SCLK
MOSI
MISO
CS
15429-068
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 26 of 42
I2C PROTOCOL
The ADXL357 supports point to point I2C communication.
However, when sharing an SDA bus, the ADXL357 may prevent
communication with other devices on that bus. If at any point,
even when the ADXL357 is not being addressed, the 0x3A and
0x3B bytes (when the ADXL357 device ID is set to 0x1D), or
the 0xA6 and 0xA7 bytes (when the ADXL357 device ID is set
to 0x53) are transmitted on the SDA bus, the ADXL357 responds
with an acknowledge bit and pulls the SDA line down. For
example, this response can occur when reading or writing the
data bytes (0x3A/0x3B or 0xA6/0xA7) to another sensor on the
bus. When the ADXL357 pulls the SDA line down, communica-
tion with other devices on the bus may be interrupted. To
resolve this, the ADXL357 must be connected to a separate SDA
bus, or the SCL pin must be switched high when communication
with the ADXL357 is not desired (it is normally grounded).
The ADXL357 supports standard (100 kHz), fast (up to 1 MHz)
and high speed (up to 3.4 MHz) data transfer modes when the
bus parameters in Table 4 are met. There is no minimum SCL
frequency, with the exception that, when reading data, the clock
must be fast enough to read an entire sample set before new data
overwrites it. Single- or multiple-byte reads/writes are supported.
With the ASEL pin low, the I2C address for the device is 0x1D
and an alternate I2C address of 0x53 can be chosen by pulling
the ASEL pin high.
There are no internal pull-up or pull-down resistors for any
unused pins; therefore, there is no known state or default state
for the pins if left floating or unconnected. It is required that
SCLK/VSSIO be connected to ground when communicating to
the ADXL357 using I2C.
Due to communication speed limitations, the maximum output
data rate when using the 400 kHz I2C mode is 800 Hz, and it
scales linearly with a change in the I2C communication speed.
For example, using I2C at 100 kHz limits the maximum ODR to
200 Hz. Operation at an output data rate above the recommended
maximum may result in an undesirable effect on the acceleration
data, including missing samples or additional noise.
Figure 69 to Figure 71 detail the I2C protocol timing. The I2C
interface can be used on most buses operating in I2C standard
mode (100 kHz), fast mode (400 kHz), fast mode plus (1 MHz),
and high speed mode (3.4 MHz). The ADXL357 I2C device ID
is as follows:
ASEL (pin) = 0, device address = 0x1D
ASEL (pin) = 1, device address = 0x53
If other devices are connected to the same I2C bus, the nominal
operating voltage level of these other devices cannot exceed
VDDIO by more than 0.3 V. External pull-up resistors, RP, are
necessary for proper I2C operation.
READING ACCELERATION OR TEMPERATURE
DATA FROM THE INTERFACE
Acceleration data is left justified and has a register address
order of most significant data to least significant data, which
allows the user to use multibyte transfers and to take only as
much data as requiredeither 8 bits, 16 bits, or 20 bits, plus the
marker. Temperature data is 12 bits unsigned, right justified.
The ADXL357 temperature value is split over two bytes, but is
not double-buffered, meaning the value can update between
readings of the two registers. The data in XDATA, YDATA, and
ZDATA is always the most recent available. It is not guaranteed
that XDATA, YDATA, and ZDATA form a set corresponding to
one sample point in time. The routine used to retrieve the data
from the device controls this data set continuity. If data transfers
are initiated when the DATA_RDY bit goes high and completes
in a time approximately equal to 1/ODR, XDATA, YDATA, and
ZDATA apply to the same data set.
For multibyte read or write transactions through either serial
interface, the internal register address auto-increments. When
the top of the register address range, 0x3FF, is reached the auto-
increment stops and does not wrap back to Hexadecimal
Address 0x00.
The address auto-increment function disables when the FIFO
address is used, so that data can be read continuously from the
FIFO as a multibyte transaction. In cases where the starting
address of a multibyte transaction is less than the FIFO address,
the address auto-increments until reaching the FIFO address,
and then stops at the FIFO address.
Figure 69. I2C Timing DiagramSingle-Byte Read
Figure 70. I2C Timing DiagramSingle-Byte Write
10 11 12 13 14 15 16 17 18 19 28 2920 21 22 23 24 25 26 27 30 31 32 33 34 35 36 37123456789
A60A5 A4 A3 A2 A1 A0 D6
0D5 D4 D3 D2 D1 D0 AKAKAK A6 A5 A4 A3 A2 A1 A0
A6 A5 A4 A3 A2 A1 A0 RW
RW
SCL
START REPEAT
START
DEVICE ADDRESS
SINGLE BYTE READ
REGISTER ADDRESS DEVICE ADDRESS DATA BYTE
STOP
SDA
AK
INDICATE SDA IS
CONTROLLED BY ADXL357
15429-069
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27123456789
START
DEVICE ADDRESS REGISTER ADDRESS DATA BYTE
STOP
SCL
SDA
A60A5 A4 A3 A2 A1 A0 AK D6D7 D5 D4 D3 D2 D1 D0 AK
A6 A5 A4 A3 A2 A1 A0 RW AK
15429-070
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 27 of 42
Figure 71. I2C Timing DiagramMultibyte Write
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 19123456789
SCL
START
DEVICE ADDRESS REGISTER ADDRESS DATA BYTE 1 DATA BYTE n
SDA
A6
0A5 A4 A3 A2 A1 A0 AK D6
D7 D5 D4 D3 D2 D1 D0 D7AK D0 AK D6D7 D5 D4 D3 D2 D1 D0 AK
A6 A5 A4 A3 A2 A1 A0 RW AK
15429-071
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 28 of 42
FIFO
FIFO operates in a stream mode; that is, when the FIFO
overruns new data overwrites the oldest data in the FIFO. A
read from the FIFO address guarantees that the three bytes
associated with the acceleration measurement on an axis all
pertain to the same measurement. If the FIFO never overflows,
the data is always taken out in sets (multiples of three data
points).
There are 96 21-bit locations in the FIFO. Each location
contains 20 bits of data and a marker bit for the x-axis data. A
single-byte read from the FIFO address pops one location from
the FIFO. A multibyte read to the FIFO location pops the FIFO
on the read of the first byte and every third byte read thereafter.
Figure 72 shows the organization of the data in the FIFO. The
acceleration data is twos complement, 20-bit data. The FIFO
control logic inserts the two virtual bits (0b00) between the data
bits and the empty indicator bit. Bit 1 indicates that an attempt
was made to read an empty FIFO, and that the data is not valid
acceleration data. Bit 0 is a marker bit to identify the x-axis,
which allows a user to verify that the FIFO data was correctly
read. An acceleration data point for a given axis occupies one
FIFO location. The read pointer, RD_PTR, points to the oldest
stored data that was not read already from the interface (see
Figure 72). There are no physical x-acceleration, y-acceleration, or
z-acceleration data registers. This data also comes directly from
the most recent data set in the FIFO, which points to by the
z pointer, Z_PTR (see Figure 72).
Figure 72. FIFO Data Organization
1
0
0
1
0
Z17 Z16 Z15 Z14 Z13 Z12 Z11 Z10 Z9 Z8 Z7 Z6 Z5 Z4 Z3 Z2 Z1 Z0
Z3 Z2 Z1 Z0
Y3 Y2 Y1 Y0
X3 X2 X1 X0
X3 X2 X1 X0
Y3 Y2 Y1 Y0
0
DATA SET. SAMPLE POINT
IS THE SAME ACROSS
A SINGLE X-AXIS, Y-AXIS,
AND Z-AXIS DATA SET.
RD_PTR
Z_PTR
Z_PTR – 1
Z_PTR – 2
X-AXIS MARKER
VIRTUAL BITS
(NOT ALLOCATED IN THE FIFO)
ACCELERATION DATA
ASCENDING SPI ADDRESSES
Z19 Z18
Y17 Y16 Y15 Y14 Y13 Y12 Y11 Y10 Y9 Y8 Y7 Y6 Y5 Y4Y19 Y18
Y17 Y16 Y15 Y14 Y13 Y12 Y11 Y10 Y9 Y8 Y7 Y6 Y5 Y4Y19 Y18
X17 X16 X15 X14 X13 X12 X11 X10 X9 X8 X7 X6 X5 X4X19 X18
X17 X16 X15 X14 X13 X12 X11 X10 X9 X8 X7 X6 X5 X4X19 X18
Z17 Z16 Z15 Z14 Z13 Z12 Z11 Z10 Z9 Z8 Z7 Z6 Z5 Z4Z19 Z18
1
Z_PTR + 1 00000000 00000000 0000001
0
0
0
0
0
0
EMPTY INDICATOR
ASCENDING FIFO ADDRESSES
ASCENDING
SPI ADDRESSES
15429-072
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 29 of 42
INTERRUPTS
The status register (Register 0x04) contains five individual bits,
four of which can be mapped to either the INT1 pin, the INT2 pin,
or both. The polarity of the interrupt, active high or active low,
is also selectable via the INT_POL bit in the range (Register 0x2C)
register. In general, the status register clears when read, but this
is not the case if the condition that caused the interrupt persists
after the read of the register. The definition of persist varies
slightly in each case, but it is described in the DATA_RDY,
DRDY Pin, FIFO_FULL, FIFO_OVR, and Activity sections.
The DRDY pin is similar to an interrupt pins (INTx) but clears
very differently. This case is also described.
DATA_RDY
The DATA_RDY bit is set when new acceleration data is
available to the interface. It clears on a read of the status register.
It is not set again until acceleration data that is newer than the
status register read is available.
Special logic on the clear of the DATA_RDY bit covers the
corner case where new data arrives during the read of the status
register. In this case, the data ready condition may be missed
completely. This logic results in a delay of the clearing of
DATA_RDY of up to four 512 kHz cycles.
DRDY PIN
The DRDY pin is not a status register bit; it instead behaves
similar to an unmaskable interrupt. DRDY is set when new
acceleration data is available to the interface. It clears on a read
of the FIFO, on a read of XDATA, YDATA, or ZDATA, or by an
autoclear function that occurs approximately halfway between
output acceleration data sets.
DRDY is always active high. The INT_POL bit does not affect
DRDY. In external sync modes (EXT_SYNC = 01, EXT_SYNC =
10), the first few DRDY pulses after initial synchronization can
be lost or corrupted. The length of this potential corruption is
less than the group delay.
FIFO_FULL
The FIFO_FULL bit is set when the entries in the FIFO are
equal to the setting of the FIFO_SAMPLES bits. It clears as
follows:
If the number of entries in the FIFO is less than the
number of samples indicated by the FIFO_SAMPLES bits,
which is only the case if sufficient data is read from the
FIFO.
On a read of the status register, but only when the entries
in the FIFO are less than the FIFO_SAMPLES bits.
FIFO_OVR
The FIFO_OVR bit is set when the FIFO is so far overrange that
data is lost. The specified size of the FIFO is 96 locations. The
FIFO_OVR is set only when there is an attempt to write past
this 96 location limit.
A read of the status register clears FIFO_OVR. It is not set again
until data is lost subsequent to this data register read.
ACTIVITY
The activity bit (Register 0x04, Bit 3) is set when the measured
acceleration on any axis is above the ACT_THRESH bits for
ACT_COUNT consecutive measurements. An overthreshold
condition can shift from one axis to another on successive
measurements and is still counted toward the consecutive
ACT_COUNT count.
A read of the status register clears the activity bit (Register 0x04,
Bit 3), but it sets again at the end of the next measurement if the
activity bit (Register 0x04, Bit 3) conditions are still satisfied.
NVM_BUSY
The NVM_BUSY bit indicates that the nonvolatile memory
(NVM) controller is busy, and it cannot be accessed to read,
write, or generate an interrupt.
A status register read that occurs after the NVM controller is no
longer busy clears NVM_BUSY.
EXTERNAL SYNCHRONIZATION AND
INTERPOLATION
There are three possible synchronization options for the ADXL357,
shown in Figure 73 to Figure 75. For clarity, the clock frequencies
and delays are drawn to scale. The labels in Figure 73 to Figure 75
are defined as follows:
Internal ODR is the alignment of the decimated output
data based on the internal clock.
ADC CLK shows the internal master clock rate
DRDY is an output indicator signaling a sample is ready.
The three modes are as follows:
No external synchronization (internal clocks used)
Synchronization with interpolation filter enabled
Sync with an external sync and clock signals, no
interpolation filter
EXT_SYNC = 00No External Sync or Interpolation
For this case, an internal clock that serves as the synchronization
master generates the data. No external signals are required, and
this is used commonly when the external processor retrieves
data from the device asynchronously and absolute synchronization
to an external source is not required. Use Register 0x28 to program
the ODR.
The device outputs a DRDY (active high) to signal that a new
sample is available, and data is retrieved from the real-time
registers or the FIFO. The group delay is based on the
decimation setting as shown in Table 10.
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 30 of 42
EXT_SYNC = 10—External Sync with Interpolation
In this case, the internal clock generates data; however, an
interpolation filter provides additional time resolution of 64
times the programmed ODR. Synchronization using interpolation
filters and an external ODR clock is commonly used when the
external processor can provide a synchronization signal (which
is asynchronous to the internal clock) at the desired ODR.
Synchronization with the interpolation filter enabled
(EXT_SYNC = 10) allows the nonsynchronous external clock to
output data most closely associated with the external clock
rising edge. The interpolation filter provides a frequency
resolution related to ODR (see Table 12).
The advantage of this mode is that data is available at a user defined
sample rate and is asynchronous to the internal oscillator. The
disadvantage of this mode is that the group delay is increased,
with increased attenuation at the band edge. Additionally,
because there is a limit to the time resolution, there is some
distortion related to the mismatch of the external sync relative
to the internal oscillator. This mismatch degrades spectral
performance. The group delay is based on the decimation
setting and interpolation setting (see Table 12). Table 13 shows
the delay between the SYNC signal (input) to DRDY (output).
Table 13. EXT_SYNC = 10, DRDY Delay
ODR_LPF Delay (Oscillator Cycles)
0x0 8
0x1 10
0x2 14
0x3 22
0x4 38
0x5 70
0x6 134
0x7 262
0x8 1031
0x9 2054
0x10 4102
EXT_SYNC = 01—External Sync and External Clock, No
Interpolation Filter
In this case, an external source provides an external clock at a
frequency of 4 × 64 × ODR. The external clock becomes the
master clock source for the device. In addition, an external
synchronization signal is needed to align the decimation filter
output to a specific clock edge, which provides full external
synchronization and is commonly used when a fixed external
clock captures and processes data, and asynchronous clocks are not
allowed. When using multiple sensors, synchronization with an
external master clock is beneficial and requires time alignment.
When configured for EXT_SYNC = 01 with an ODR of 4 kHz,
the user must supply an external clock at 1.024 MHz (64 × 4 ×
4 kHz) on the INT2 pin (Pin 13), and an external synchronization
on DRDY pin (Pin 14), as shown in Table 14.
Special restrictions when using this mode include the following:
An external clock (EXT_CLK) must be provided as well as
an external sync.
The frequency of EXT_CLK must be exactly 4 × 64 × ODR.
The width of sync must be a minimum of four EXT_CLK
periods.
The phase of sync must meet an approximate 25 ns setup
time to the EXT_CLK rising edge.
When using the EXT_SYNC mode and without providing sync,
the device runs on its own synchronization. Similarly, after
synchronization, the device continues to run synchronized to
the last sync pulse it received, which means that EXT_SYNC = 01
mode can be used with only a single synchronization pulse.
The interpolation filter provides a frequency resolution related to
the ODR (see Table 12). In this case, the data provided corresponds
to the external signal, which can be greater than the set ODR,
but the output pass band remains the same it was prior to the
interpolation filter.
Table 14. Multiplexing of INT2 and DRDY
Register or Bit Fields Pins
EXT_CLK EXT_SYNC[1:0] INT_MAP[7:4] INT2 (Pin 13) DRDY (Pin 14) Comments
0 00 0000 Low DRDY Synchronization is to the internal clocks, and there is no
external clock synchronization.
0 00 Not 0000 INT2 DRDY
1 00 0000 EXT_CLK DRDY
1 00 Not 00002 EXT_CLK DRDY
0 01 0000 DRDY SYNC These options reset the digital filters on every
synchronization pulse and are not recommended.
0 011 Not 0000 INT2 SYNC
1 011 0000 EXT_CLK SYNC External synchronization, no interpolation filter, and
DRDY (active high) signals that data is ready. Data
represents a sample point group delay earlier in time.
1 011 Not 00002 EXT_CLK SYNC
0 10 0000 DRDY SYNC External synchronization, interpolation filter, and DRDY
(active high) signals that data is ready. Data sample
group delay earlier in time.
0 101 Not 0000 INT2 SYNC
1 101 0000 EXT_CLK SYNC
1 101 Not 0000 EXT_CLK SYNC
1 No DRDY.
2 No INT2, even though it is enabled.
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 31 of 42
Figure 73. External Synchronization OptionEXT_SYNC = 00, Internal Sync
Figure 74. External Synchronization OptionEXT_SYNC = 10, External Sync, External Clock, Interpolation Filter
Figure 75. External Synchronization OptionEXT_SYNC = 01, External Sync, No Interpolation Filter
INTERNAL ODR
GROUP DELAY
(FIXED RELATIVE TO DRDY)
SAMPLE POINT
ADC MOD. CLK.
64× ODR
DRDY
15429-073
INTERNAL ODR
INTERPOLATOR
64× ODR
DRDY
GROUP DELAY
(FIXED RELATIVE TO SYNC) INTERFACE SYNCHRONIZATION DELAY
SAMPLE POINT
SYNC
110% ODR
15429-074
INTERNAL ODR
DRDY
GROUP DELAY
(FIXED RELATIVE TO SYNC)
SAMPLE POINT
LOST SAMPLE
SYNCHRONIZE
EXT_CLK
(4 × 64) × SYNC
SYNC
15429-075
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 32 of 42
ADXL357 REGISTER MAP
Note that while configuring the ADXL357 in an application, all configuration registers must be programmed before enabling measurement
mode in the POWER_CTL register. When the ADXL357 is in measurement mode, only the following configurations can change: the
HPF_CORNER bits in the filter register, the INT_MAP register, the ST1 and ST2 bits in the SELF_TEST register, and the reset register.
Table 15. ADXL357 Register Map
Hex.
Addr. Register Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset R/W
0x00 DEVID_AD DEVID_AD 0xAD R
0x01 DEVID_MST DEVID_MST 0x1D R
0x02 PARTID PARTID 0xED R
0x03 REVID REVID 0x01 R
0x04 Status Reserved NVM_
BUSY
Activity FIFO_OVR FIFO_FULL DATA_RDY 0x00 R
0x05 FIFO_ENTRIES Reserved FIFO_ENTRIES 0x00 R
0x06 TEMP2 Reserved Temperature, Bits[11:8] 0x00 R
0x07 TEMP1 Temperature, Bits[7:0] 0x00 R
0x08 XDATA3 XDATA, Bits[19:12] 0x00 R
0x09 XDATA2 XDATA, Bits[11:4] 0x00 R
0x0A XDATA1 XDATA, Bits[3:0] Reserved 0x00 R
0x0B YDATA3 YDATA, Bits[19:12] 0x00 R
0x0C YDATA2 YDATA, Bits[11:4] 0x00 R
0x0D YDATA1 YDATA, Bits[3:0] Reserved 0x00 R
0x0E ZDATA3 ZDATA, Bits[19:12] 0x00 R
0x0F ZDATA2 ZDATA, Bits[11:4] 0x00 R
0x10 ZDATA1 ZDATA, Bits[3:0] Reserved 0x00 R
0x11 FIFO_DATA FIFO_DATA 0x00 R
0x1E OFFSET_X_H OFFSET_X, Bits[15:8] 0x00 R/W
0x1F OFFSET_X_L OFFSET_X, Bits[7:0] 0x00 R/W
0x20 OFFSET_Y_H OFFSET_Y, Bits[15:8] 0x00 R/W
0x21 OFFSET_Y_L OFFSET_Y, Bits[7:0] 0x00 R/W
0x22 OFFSET_Z_H OFFSET_Z, Bits[15:8] 0x00 R/W
0x23 OFFSET_Z_L OFFSET_Z, Bits[7:0] 0x00 R/W
0x24 ACT_EN Reserved ACT_Z ACT_Y ACT_X 0x00 R/W
0x25 ACT_THRESH_H ACT_THRESH, Bits[15:8] 0x00 R/W
0x26 ACT_THRESH_L ACT_THRESH, Bits[7:0] 0x00 R/W
0x27 ACT_COUNT ACT_COUNT 0x01 R/W
0x28 Filter Reserved HPF_CORNER ODR_LPF 0x00 R/W
0x29 FIFO_SAMPLES Reserved FIFO_SAMPLES 0x60 R/W
0x2A INT_MAP ACT_EN2 OVR_EN2 FULL_EN2 RDY_EN2 ACT_EN1 OVR_EN1 FULL_EN1 RDY_EN1 0x00 R/W
0x2B Sync Reserved EXT_CLK EXT_SYNC 0x00 R/W
0x2C Range I2C_HS INT_POL Reserved Range 0x81 R/W
0x2D POWER_CTL Reserved DRDY_OFF TEMP_OFF Standby 0x01 R/W
0x2E SELF_TEST Reserved ST2 ST1 0x00 R/W
0x2F Reset Reset 0x00 W
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 33 of 42
REGISTER DEFINITIONS
This section describes the functions of the ADXL357 registers. The ADXL357 powers up with the default register values, as shown in the
Reset column of Table 15.
ANALOG DEVICES ID REGISTER
This register contains the Analog Devices ID, 0xAD.
Address: 0x00, Reset: 0xAD, Name: DEVID_AD
Table 16. Bit Descriptions for DEVID_AD
Bits Bit Name Settings Description Reset Access
[7:0] DEVID_AD Analog Devices ID 0xAD R
ANALOG DEVICES MEMS ID REGISTER
This register contains the Analog Devices MEMS ID, 0x1D.
Address: 0x01, Reset: 0x1D, Name: DEVID_MST
Table 17. Bit Descriptions for DEVID_MST
Bits Bit Name Settings Description Reset Access
[7:0] DEVID_MST Analog Devices MEMS ID 0x1D R
DEVICE ID REGISTER
This register contains the device ID, 0xED (355 octal).
Address: 0x02, Reset: 0xED, Name: PARTID
Table 18. Bit Descriptions for PARTID
Bits Bit Name Settings Description Reset Access
[7:0] PARTID Device ID (355 octal) 0xED R
PRODUCT REVISION ID REGISTER
This register contains the product revision ID, beginning with 0x00 and incrementing for each subsequent revision.
Address: 0x03, Reset: 0x01, Name: REVID
Table 19. Bit Descriptions for REVID
Bits Bit Name Settings Description Reset Access
[7:0] REVID Mask revision 0x01 R
STATUS REGISTER
This register includes bits that describe the various conditions of the ADXL357.
Address: 0x04, Reset: 0x00, Name: Status
Table 20. Bit Descriptions for Status
Bits Bit Name Settings Description Reset Access
[7:5] Reserved Reserved. 0x0 R
4 NVM_BUSY NVM controller is busy with either refresh, programming, or built in, self test (BIST). 0x0 R
3 Activity Activity, as defined in the ACT_THRESH_x and ACT_COUNT registers, is detected. 0x0 R
2 FIFO_OVR FIFO has overrun, and the oldest data is lost. 0x0 R
1 FIFO_FULL FIFO watermark is reached. 0x0 R
0 DATA_RDY A complete x-axis, y-axis, and z-axis measurement was made and results can be read. 0x0 R
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 34 of 42
FIFO ENTRIES REGISTER
This register indicates the number of valid data samples present in the FIFO buffer. This number ranges from 0 to 96.
Address: 0x05, Reset: 0x00, Name: FIFO_ENTRIES
Table 21. Bit Descriptions for FIFO_ENTRIES
Bits Bit Name Settings Description Reset Access
7 Reserved Reserved 0x0 R
[6:0] FIFO_ENTRIES Number of data samples stored in the FIFO 0x0 R
TEMPERATURE DATA REGISTERS
These two registers contain the uncalibrated temperature data. The nominal intercept is 1852 LSB at 25°C and the nominal slope is
−9.05 LSB/°C. TEMP2 contains the four most significant bits, and TEMP1 contains the eight least significant bits of the 12-bit value. The
ADXL357 temperature value is not double-buffered, meaning the value can update between reading of the two registers.
Address: 0x06, Reset: 0x00, Name: TEMP2
Table 22. Bit Descriptions for TEMP2
Bits Bit Name Settings Description Reset Access
[7:4] Reserved Reserved.
[3:0] Temperature, Bits[11:8] Uncalibrated temperature data 0x0 R
Address: 0x07, Reset: 0x00, Name: TEMP1
Table 23. Bit Descriptions for TEMP1
Bits Bit Name Settings Description Reset Access
[7:0] Temperature, Bits[7:0] Uncalibrated temperature data 0x0 R
X-AXIS DATA REGISTERS
These three registers contain the x-axis acceleration data. Data is left justified and formatted as twos complement.
Address: 0x08, Reset: 0x00, Name: XDATA3
Table 24. Bit Descriptions for XDATA3
Bits Bit Name Settings Description Reset Access
[7:0] XDATA, Bits[19:12] X-axis data 0x0 R
Address: 0x09, Reset: 0x00, Name: XDATA2
Table 25. Bit Descriptions for XDATA2
Bits Bit Name Settings Description Reset Access
[7:0] XDATA, Bits[11:4] X-axis data 0x0 R
Address: 0x0A, Reset: 0x00, Name: XDATA1
Table 26. Bit Descriptions for XDATA1
Bits Bit Name Settings Description Reset Access
[7:4] XDATA, Bits[3:0] X-axis data 0x0 R
[3:0] Reserved Reserved 0x0 R
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 35 of 42
Y-AXIS DATA REGISTERS
These three registers contain the y-axis acceleration data. Data is left justified and formatted as twos complement.
Address: 0x0B, Reset: 0x00, Name: YDATA3
Table 27. Bit Descriptions for YDATA3
Bits Bit Name Settings Description Reset Access
[7:0] YDATA, Bits[19:12] Y-axis data 0x0 R
Address: 0x0C, Reset: 0x00, Name: YDATA2
Table 28. Bit Descriptions for YDATA2
Bits Bit Name Settings Description Reset Access
[7:0] YDATA, Bits[11:4] Y-axis data 0x0 R
Address: 0x0D, Reset: 0x00, Name: YDATA1
Table 29. Bit Descriptions for YDATA1
Bits Bit Name Settings Description Reset Access
[7:4] YDATA, Bits[3:0] Y-axis data 0x0 R
[3:0] Reserved Reserved 0x0 R
Z-AXIS DATA REGISTERS
These three registers contain the z-axis acceleration data. Data is left justified and formatted as twos complement.
Address: 0x0E, Reset: 0x00, Name: ZDATA3
Table 30. Bit Descriptions for ZDATA3
Bits Bit Name Settings Description Reset Access
[7:0] ZDATA, Bits[19:12] Z-axis data 0x0 R
Address: 0x0F, Reset: 0x00, Name: ZDATA2
Table 31. Bit Descriptions for ZDATA2
Bits Bit Name Settings Description Reset Access
[7:0] ZDATA, Bits[11:4] Z-axis data 0x0 R
Address: 0x10, Reset: 0x00, Name: ZDATA1
Table 32. Bit Descriptions for ZDATA1
Bits Bit Name Settings Description Reset Access
[7:4] ZDATA, Bits[3:0] Z-axis data 0x0 R
[3:0] Reserved Reserved 0x0 R
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 36 of 42
FIFO ACCESS REGISTER
Address: 0x11, Reset: 0x00, Name: FIFO_DATA
Read this register to access data stored in the FIFO.
Table 33. Bit Descriptions for FIFO_DATA
Bits Bit Name Settings Description Reset Access
[7:0] FIFO_DATA FIFO data is formatted to 24 bits, 3 bytes, most significant byte first. A read to this
address pops an effective three equal byte words of axis data from the FIFO. Two
subsequent reads or a multibyte read completes the transaction of this data onto the
interface. Continued reading or a sustained multibyte read of this field continues to
pop the FIFO every third byte. Multibyte reads to this address do not increment the
address pointer. If this address is read due to an auto-increment from the previous
address, it does not pop the FIFO. Instead, it returns zeros and increments onto the
next address.
0x0 R
X-AXIS OFFSET TRIM REGISTERS
Address: 0x1E, Reset: 0x00, Name: OFFSET_X_H
Table 34. Bit Descriptions for OFFSET_X_H
Bits Bit Name Settings Description Reset Access
[7:0] OFFSET_X,
Bits[15:8]
Offset added to x-axis data after all other signal processing. Data is in twos complement
format. The bit significance of OFFSET_X[15:0] matches the significance of XDATA[19:4].
0x0 R/W
Address: 0x1F, Reset: 0x00, Name: OFFSET_X_L
Table 35. Bit Descriptions for OFFSET_X_L
Bits Bit Name Settings Description Reset Access
[7:0] OFFSET_X,
Bits[7:0]
Offset added to x-axis data after all other signal processing. Data is in twos complement
format. The significance of OFFSET_X[15:0] matches the significance of XDATA[19:4].
0x0 R/W
Y-AXIS OFFSET TRIM REGISTERS
Address: 0x20, Reset: 0x00, Name: OFFSET_Y_H
Table 36. Bit Descriptions for OFFSET_Y_H
Bits Bit Name Settings Description Reset Access
[7:0] OFFSET_Y,
Bits[15:8]
Offset added to y-axis data after all other signal processing. Data is in twos complement
format. The significance of OFFSET_Y[15:0] matches the significance of YDATA[19:4].
0x0 R/W
Address: 0x21, Reset: 0x00, Name: OFFSET_Y_L
Table 37. Bit Descriptions for OFFSET_Y_L
Bits Bit Name Settings Description Reset Access
[7:0] OFFSET_Y,
Bits[7:0]
Offset added to y-axis data after all other signal processing. Data is in twos complement
format. The significance of OFFSET_Y[15:0] matches the significance of YDATA[19:4].
0x0 R/W
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 37 of 42
Z-AXIS OFFSET TRIM REGISTERS
Address: 0x22, Reset: 0x00, Name: OFFSET_Z_H
Table 38. Bit Descriptions for OFFSET_Z_H
Bits Bit Name Settings Description Reset Access
[7:0] OFFSET_Z,
Bits[15:8]
Offset added to z-axis data after all other signal processing. Data is in twos complement
format. The significance of OFFSET_Z[15:0] matches the significance of ZDATA[19:4].
0x0 R/W
Address: 0x23, Reset: 0x00, Name: OFFSET_Z_L
Table 39. Bit Descriptions for OFFSET_Z_L
Bits Bit Name Settings Description Reset Access
[7:0] OFFSET_Z,
Bits[7:0]
Offset added to z-axis data after all other signal processing. Data is in twos complement
format. The significance of OFFSET_Z[15:0] matches the significance of ZDATA[19:4].
0x0 R/W
ACTIVITY ENABLE REGISTER
Address: 0x24, Reset: 0x00, Name: ACT_EN
Table 40. Bit Descriptions for ACT_EN
Bits Bit Name Settings Description Reset Access
[7:3] Reserved Reserved. 0x0 R
2 ACT_Z Z-axis data is a component of the activity detection algorithm. 0x0 R/W
1 ACT_Y Y-axis data is a component of the activity detection algorithm. 0x0 R/W
0 ACT_X X-axis data is a component of the activity detection algorithm. 0x0 R/W
ACTIVITY THRESHOLD REGISTERS
Address: 0x25, Reset: 0x00, Name: ACT_THRESH_H
Table 41. Bit Descriptions for ACT_THRESH_H
Bits Bit Name Settings Description Reset Access
[7:0] ACT_THRESH[15:8] Threshold for activity detection. Acceleration magnitude must be above
ACT_THRESH to trigger the activity counter. ACT_THRESH is an unsigned
magnitude. The significance of ACT_THRESH[15:0] matches the significance
of XDATA[18:3], YDATA[18:3], and ZDATA[18:3].
0x0 R/W
Address: 0x26, Reset: 0x00, Name: ACT_THRESH_L
Table 42. Bit Descriptions for THRESH_ACT_X_L
Bits Bit Name Settings Description Reset Access
[7:0] ACT_THRESH[7:0] Threshold for activity detection. The acceleration magnitude must be greater
than the value in ACT_THRESH to trigger the activity counter. ACT_THRESH is
an unsigned magnitude. The significance of ACT_THRESH[15:0] matches the
bit significance of XDATA[18:3], YDATA[18:3], and ZDATA[18:3].
0x0 R/W
ACTIVITY COUNT REGISTER
Address: 0x27, Reset: 0x01, Name: ACT_COUNT
Table 43. Bit Descriptions for ACT_COUNT
Bits Bit Name Settings Description Reset Access
[7:0] ACT_COUNT Number of consecutive events above threshold (from ACT_THRESH) required to
detect activity
0x1 R/W
ADXL356/ADXL357 Data Sheet
Rev. 0 | Page 38 of 42
FILTER SETTINGS REGISTER
Address: 0x28, Reset: 0x00, Name: Filter
Use this register to specify parameters for the internal high-pass and low-pass filters.
Table 44. Bit Descriptions for Filter
Bits Bit Name Settings Description Reset Access
7 Reserved Reserved 0x0 R
[6:4] HPF_CORNER −3 dB filter corner for the first-order, high-pass filter relative to the ODR 0x0 R/W
000 Not applicable, no high-pass filter enabled
001 247 × 10−3 × ODR
010 62.084 × 10−3 × ODR
011 15.545 × 10−3 × ODR
100 3.862 × 10−3 × ODR
101 0.954 × 10−3 × ODR
110 0.238 × 10−3 × ODR
[3:0] ODR_LPF ODR and low-pass filter corner 0x0 R/W
0000 4000 Hz and 1000 Hz
0001 2000 Hz and 500 Hz
0010 1000 Hz and 250 Hz
0011 500 Hz and 125 Hz
0100 250 Hz and 62.5 Hz
0101 125 Hz and 31.25 Hz
0110 62.5 Hz and 15.625 Hz
0111 31.25 Hz and 7.813 Hz
1000 15.625 Hz and 3.906 Hz
1001 7.813 Hz and 1.953 Hz
1010 3.906 Hz and 0.977 Hz
FIFO SAMPLES REGISTER
Address: 0x29, Reset: 0x60, Name: FIFO_SAMPLES
Use the FIFO_SAMPLES value to specify the number of samples to store in the FIFO. The default value of this register is 0x60 to avoid
triggering the FIFO watermark interrupt.
Table 45. Bit Descriptions for FIFO_SAMPLES
Bits Bit Name Settings Description Reset Access
7 Reserved Reserved. 0x0 R
[6:0] FIFO_SAMPLES Watermark number of samples stored in the FIFO that triggers a FIFO_FULL condition.
Values range from 1 to 96.
0x60 R/W
INTERRUPT PIN (INTx) FUNCTION MAP REGISTER
Address: 0x2A, Reset: 0x00, Name: INT_MAP
The INT_MAP register configures the interrupt pins. Bits[7:0] select which functions generate an interrupt on the INT1 and INT2 pins.
Multiple events can be configured. If the corresponding bit is set to 1, the function generates an interrupt on the interrupt pins.
Table 46. Bit Descriptions for INT_MAP
Bits Bit Name Settings Description Reset Access
7 ACT_EN2 Activity interrupt enable on INT2 0x0 R/W
6 OVR_EN2 FIFO_OVR interrupt enable on INT2 0x0 R/W
5 FULL_EN2 FIFO_FULL interrupt enable on INT2 0x0 R/W
4 RDY_EN2 DATA_RDY interrupt enable on INT2 0x0 R/W
3 ACT_EN1 Activity interrupt enable on INT1 0x0 R/W
2 OVR_EN1 FIFO_OVR interrupt enable on INT1 0x0 R/W
1 FULL_EN1 FIFO_FULL interrupt enable on INT1 0x0 R/W
0 RDY_EN1 DATA_RDY interrupt enable on INT1 0x0 R/W
Data Sheet ADXL356/ADXL357
Rev. 0 | Page 39 of 42
DATA SYNCHRONIZATION
Address: 0x2B, Reset: 0x00, Name: Sync
Use this register to control the external timing triggers.
Table 47. Bit Descriptions for Sync
Bits Bit Name Settings Description Reset Access
[7:3] Reserved Reserved. 0x0 R
2 EXT_CLK Enable external clock. See Table 14. Multiplexing of INT2 and DRDY Table 14 for
configuration details.
0x0 R/W
[1:0] EXT_SYNC Enable external sync control. 0x0 R/W
00 Internal sync.
01 External sync, no interpolation filter. After synchronization, and for EXT_SYNC within
specification, DATA_RDY occurs on EXT_SYNC.
10 External sync, interpolation filter, next available data indicated by DATA_RDY 14 to
8204 oscillator cycles later (longer delay for higher ODR_LPF setting), data represents
a sample point group delay earlier in time.
11 Reserved.
I2C SPEED, INTERRUPT POLARITY, AND RANGE REGISTER
Address: 0x2C, Reset: 0x81, Name: Range
Table 48. Bit Descriptions for Range
Bits Bit Name Settings Description Reset Access
7 I2C_HS I2C speed. 0x1 R/W
1 High speed mode.
0 Fast mode.
6 INT_POL Interrupt polarity. 0x0 R/W
0 INT1 and INT2 are active low.
1 INT1 and INT2 are active high.
[5:2] Reserved Reserved. 0x0 R
[1:0] Range Range. 0x1 R/W
01 ±10 g.
10 ±20 g.
11 ±