Si4430
Preliminary Rev. 0.4
57
The differential offset can be coarse compensated by the adcoffs[3:0] bits found in "Register 11h. ADC Value". Fine
compensation should be done by the microcontroller software. The main reason for the offset compensation is to
shift the negative offset voltage of the bridge sensor to the positive differential voltage range. This is essential as
the differential input mode is unipolar. The offset compensation is VDD proportional, so the VDD change has no
influence on the measured value.
Figure 26. ADC Differential Input Offset for Sensor Offset Coarse Compensation
adcoffs[3]
Input Offset (% of VDD)
0
0 if adcoffs[2:0] = 0
–(8 – adcoffs[2:0]) x 0.12
1
adcoffs[2:0] x 0.12
0.84 %
–0.84 %
0 %
0 1
15
Input Offset
adcoffs[3:0]
8
