MMA8451Q Просмотр технического описания (PDF) - Freescale Semiconductor

Номер в каталоге

Компоненты Описание

производитель

MMA8451Q

3-Axis, 14-bit/8-bit Digital Accelerometer

Freescale Semiconductor 

3

Terminology

3.1 Sensitivity

The sensitivity is represented in counts/g. In 2g mode the sensitivity is 4096 counts/g. In 4g mode the sensitivity is 2048 counts/

g and in 8g mode the sensitivity is 1024 counts/g.

3.2 Zero-g Offset

Zero-g Offset (TyOff) 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 0g in X-axis and 0g in Y-axis whereas the Z-axis will measure 1g. The output

is ideally in the middle of the dynamic range of the sensor (content of OUT Registers 0x00, data expressed as 2's complement

number). 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.

3.3 Self-Test

Self-Test checks the transducer functionality without 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

test-force.

MMA8451Q

10

Sensors

Freescale Semiconductor, Inc.

Share Link: