Freescale Semiconductor FRDM-FXS-MULTI 데이터 시트
FXOS8700CQ
Sensors
Freescale Semiconductor, Inc.
Freescale Semiconductor, Inc.
11
3
Terminology
3.1
Sensitivity
Sensitivity is represented in mg/LSB for the accelerometer and
μT/LSB for the magnetometer. The magnetometer sensitivity is
fixed at 0.1
μT/LSB. The accelerometer sensitivity changes with the full-scale range selected by the user. Accelerometer
sensitivity is 0.244 mg/LSB in 2 g mode, 0.488 mg/LSB in 4 g mode, and 0.976 mg/LSB in 8 g mode.
3.2
Zero-g and Zero-Flux offset
For the accelerometer, zero-g offset describes the deviation of the output values from the ideal values when the sensor is
stationary. With an accelerometer stationary on a level horizontal surface, the ideal output is 0 g for the X and Y axes, and 1 g
for the Z-axis. The deviation of each output from the ideal value is called zero-g offset. Offset is to some extent a result of stress
on the sensor, and therefore, can slightly change after mounting the sensor onto a printed circuit board or exposing it to extensive
mechanical stress. For the magnetometer, zero-flux offset describes the deviation of the output signals from zero when the
device is shielded from external magnetic field sources (that is, inside a zero-gauss chamber).
stationary. With an accelerometer stationary on a level horizontal surface, the ideal output is 0 g for the X and Y axes, and 1 g
for the Z-axis. The deviation of each output from the ideal value is called zero-g offset. Offset is to some extent a result of stress
on the sensor, and therefore, can slightly change after mounting the sensor onto a printed circuit board or exposing it to extensive
mechanical stress. For the magnetometer, zero-flux offset describes the deviation of the output signals from zero when the
device is shielded from external magnetic field sources (that is, inside a zero-gauss chamber).
3.3
Self-Test
Self-Test can be used to verify the transducer and signal chain functionality without the need to apply an acceleration or magnetic
field stimulus. When the accelerometer self-test is activated, an electrostatic actuation force is applied to the sensor, simulating
a small acceleration. In this case the sensor X, Y, Z outputs will exhibit a change in DC levels related to the selected full-scale
range (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. When self-test is activated for the magnetometer,
an internal magnetic field is generated along the X, Y and Z axes. The sensor response will be the sum of the ambient magnetic
field and the self-test induced field.
field stimulus. When the accelerometer self-test is activated, an electrostatic actuation force is applied to the sensor, simulating
a small acceleration. In this case the sensor X, Y, Z outputs will exhibit a change in DC levels related to the selected full-scale
range (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. When self-test is activated for the magnetometer,
an internal magnetic field is generated along the X, Y and Z axes. The sensor response will be the sum of the ambient magnetic
field and the self-test induced field.