Datasheet ADXL251 (Analog Devices)

Dual-Axis, 60 g to 480 g Sensor with SPI and PSI5 Data Sheet ADXL251 FEATURES GENERAL DESCRIPTION User selectable sensor g ranges: ±60 g , ±120 g , ±240 g , ±480 g
The ADXL251 is a dual-axis, integrated satel ite sensor with
Dual x-axis and y-axis sensor
user selectable g ranges, compliant to the PSI5 Version 2.1 airbag
Compliant to PSI5 Version 2.1 airbag substandard
substandard, and backwards compliant to PSI5 Version 1.3.
Synchronous operation
The ADXL251 (x-axis/y-axis) enables low cost solutions for
PSI5-P10P-500/3L and others
front impact and side impact airbags, as well as satellite sensor
Daisy-chain operation with bidirectional communication
and electronic control unit (ECU) main sensor applications.
Application level serial peripheral interface (SPI)
Acceleration data is sent to the control module via a digital,
communication
2-wire current loop PSI5 bus. Communication via the SPI bus
Selectable 16-bit or 10-bit sensor data
is also available for ECU applications.
Independently programmable g range and time slot for each
The device uses an ECC protected one time programmable
axis
(OTP) memory. The sensor g range is configurable to provide
Independent fault discrimination for each axis
ful -scale measurement of ±60 g, ±120 g, ±240 g, or ±480 g
Fully differential analog signal chain
acceleration. The user can program each axis independently
0.25 µs data interpolation routine
with multiple g ranges in different time slots. In PSI5 mode,
User selectable, continuous auto-zero operation
there are four programmable time slots available. The device
High resistance to electromagnetic interference (EMI) and
transmits 16-bit or 10-bit acceleration data to the control
radio frequency interference (RFI)
module, and can be configured to include either a 1-bit parity
SPI mode supply voltage: 3.3 V and 5 V, +5%
check, or a 3-bit cyclic redundancy check (CRC).
PSI5 mode supply voltage range: 4.5 V to 11.0 V
The ADXL251 is available in a 4 mm × 4 mm LFCSP package
Qualified for automotive applications
and is specified to operate over the ful automotive temperature
APPLICATIONS
range, −40°C to +125°C.
Front impact crash sensing Side impact crash sensing FUNCTIONAL BLOCK DIAGRAM X-AXIS ONLY X-AXIS ONLY X-AXIS/Y-AXIS V SENSOR ANALOG FRONT END (SAFE) SENSOR DIGITAL SIGNAL PROCESSING COMMUNICATIONS INTERFACE DDIO g RANGE MISO SPI MOSI DIGITAL OFFSET/ OUTPUT SPI PHY AC SCLK X-AXIS DEMOD FILTER AUTO- Σ-Δ MOD SENSITIVITY DATA AMP –3dB AT ZERO DLL CALIBRATION REGISTER SERIAL CS 400Hz PORT PSI5 PSI5 IDATA DLL PHY SENSOR SELF VBP DRIVERS TEST OFFSET OFFSET OVER- OVR V V DD DD RANGE ERROR X-AXIS ONLY FLAG REG CAP TIMING STATE REGISTER DETECT GENERATOR MACHINE FILE VBN DUAL-AXIS SELF SELF ACCELER ATION ERROR TEST TEST SENSOR DIE HANDLER CHECK ERROR DCC/TP2 FLAG POR MASTER ECC STATE Y-AXIS ONLY Y-AXIS ONLY MACHINE V NVM DD MONITOR SENSOR ANALOG FRONT END (SAFE) SENSOR DIGITAL SIGNAL PROCESSING REPAIR g RANGE TEST MUX TP1 NVM DIGITAL CONTROL OFFSET/ OUTPUT Y-AXIS AC CLOCK DEMOD FILTER AUTO- Σ-Δ MOD SENSITIVITY DATA AMP –3dB AT ZERO CALIBRATION REGISTER 400Hz OTP NVM (eFuse) SENSOR SELF DRIVERS TEST OFFSET OFFSET OVER- OVR RANGE ERROR Y-AXIS ONLY TIMING FLAG STATE GENERATOR MACHINE SELF SELF TEST TEST CHECK ERROR
001
FLAG
15454- Figure 1. For more information about the ADXL251, contact the Analog Devices, Inc., Customer Interaction Center at http://www.analog.com/technical_support to connect with a technical support specialist.
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM NOTES