GENERAL DESCRIPTION
The ADXL3121 is a small, thin, low power, 3-axis accelerometer
with high resolution (13-bit) measurement up to ±12 g. Digital
output data is formatted as 16-bit twos complement and is
accessible through either a serial port interface (SPI) (3- or 4-wire)
or I2C digital interface.
The ADXL312 is well suited for car alarm or black box applications.
It measures the static acceleration of gravity in tilt-sensing
applications, as well as dynamic acceleration resulting from motion
or shock. Its high resolution (2.9 mg/LSB) enables resolution of
inclination changes of as little as 0.25°. A built-in FIFO facilitates
using oversampling techniques to improve resolution to as
little as 0.05° of inclination.
Several special sensing functions are provided. Activity and
inactivity sensing detects the presence or absence of motion and
whether the acceleration on any axis exceeds a user-set level.
These functions can be mapped to interrupt output pins. An
integrated 32 level FIFO can be used to store data to minimize
host processor intervention.
Low power modes enable intelligent motion-based power
management with threshold sensing and active acceleration
measurement at extremely low power dissipation.
The ADXL312 is supplied in a small, thin 5 mm × 5 mm ×
1.45 mm, 32-lead, LFCSP package.

FEATURES
Ultralow power: as low as 57 μA in measurement mode and
0.1 μA in standby mode at VS = 3.3 V (typical)
Power consumption scales automatically with bandwidth
User-selectable resolution
Fixed 10-bit resolution
Full resolution, where resolution increases with g range,
up to 13-bit resolution at ±12 g (maintaining 2.9 mg/LSB
scale factor in all g ranges)
Embedded FIFO technology minimizes host processor load
Built-in motion detection functions for activity/inactivity
monitoring
Supply and I/O voltage range: 2.0 V to 3.6 V
SPI (3- and 4-wire) and I2C digital interfaces
Flexible interrupt modes mappable to either interrupt pin
Measurement ranges selectable via serial command
Bandwidth selectable via serial command
Wide temperature range (−40 to +105°C)
10,000 g shock survival
Pb free/RoHS compliant
Small and thin: 5 mm × 5 mm × 1.45 mm LFCSP package
Qualified for automotive applications

APPLICATIONS
Car alarm
Hill start aid (HSA)
Electronic parking brake
Data recorder (black box)