CMA3000-D0X Datasheet, PDF (26/35 Pages) VTI technologies – 3-axis accelerometer

CMA3000-D0X Series
8 Data sheet references
8.1 Offset
CMA3000's offset will be calibrated in X = 0 g, Y = 0 g, and Z = +1 g (Z measuring axis is parallel to
earth’s gravitation) position, see Figure 18.
Z-axis in +1 g
position
Y
X
Earth’s
gravitation
Pin #1
Figure 18. CMA3000 offset (0 g) position.
8.1.1 Offset calibration error
Offset calibration error is the difference between the sensor's actual output reading and the nominal
output reading in calibration conditions. Error is calculated by
Equation 1
Offset _{X −axisCalibEr}
=
Output _{X −axis} − Output
Sens
⋅1000 ,
where Output_{X-axisCalibEr} is sensor’s X-axis calibration error in [mg], Output_X-axis is sensor’s X-axis
output reading [counts], Output is sensor’s nominal output in 0 g position and Sens sensor’s nominal
sensitivity [counts/g].
8.1.2 Offset temperature error
Offset temperature error is the difference between the sensor's output reading in different
temperatures and the sensor’s calibrated offset value at room temperature. Error is calculated by
Equation 2
Offset _{X −axisTempEr @ T}
= ^{Output X −axis @ T − Output X −axis @ RT}
Sens
⋅1000 ,
where Output_{X-axisTempEr@T} is sensor’s X-axis temperature error in [mg] in temperature T, Output_X-axis@T
is sensor’s X-axis output reading [counts] in temperature T, Output_X-axis@T X-axis output reading
[counts] at room temperature RT and Sens sensor’s nominal sensitivity [counts/g]. Sensor is in 0 g
position for every measurement point.
8.2 Sensitivity
During sensitivity calibration, the sensor is placed in ±1 g positions having one of the sensor’s
measuring axes at a time parallel to the earth’s gravitation, see Figure 19.
VTI Technologies Oy
www.vti.fi
Doc.Nr. 8281000.12
26/ 35
Rev. 0.12