FXLS8471Q Datasheet, PDF (12/75 Pages) Freescale Semiconductor, Inc – Linear Accelerometer

4
Terminology
4.1 Sensitivity
The sensitivity is represented in LSB/g. In 2-g mode the sensitivity is 4096 LSB/g. In 4-g mode the sensitivity is 2048 LSB/ g and
in 8-g mode the sensitivity is 1024 LSB/g.
4.2 Zero-g Offset
Zero-g Offset describes the deviation of an actual output signal from the ideal output signal if the sensor is stationary. A sensor
stationary on a horizontal surface will measure 0 g in X-axis and 0 g in Y-axis whereas the Z-axis will measure 1 g. A deviation from
ideal value in this case is called Zero-g offset. Offset is to some extent a result of stress on the MEMS sensor and therefore the
offset can slightly change after mounting the sensor onto a printed circuit board or exposing it to extensive mechanical stress.
4.3 Self-Test
Self-Test can be used to verify the transducer functionality without applying an external mechanical stimulus. When Self-Test is
activated, an electrostatic actuation force is applied to the sensor, simulating a small acceleration. In this case, the sensor outputs
will exhibit a change in their DC levels which are related to the selected full scale through the device sensitivity. When Self-Test is
activated, the device output level is given by the algebraic sum of the signals produced by the acceleration acting on the sensor
and by the electrostatic self-test force.
FXLS8471Q
12
Sensors
Freescale Semiconductor, Inc.