Currently I am working with the AD7195. I'm using this ADC to convert the signal from a loadcell to a digital value. The loadcell has the following specs/configuration:
|(AC) Excitation voltage||10||V|
I am trying to find out how the ADC is converting the analog value to the digital value. I searched the datasheet and found these statements:
- Code = 2^(N – 1) × [(AIN × Gain/VREF) + 1]
- The offset calibration coefficient is subtracted from the result prior to multiplication by the full-scale coefficient
So I checked my coëfficients and they are:
- offset calibration coëfficient = 8388608
- full-scale calibration coëfficient = 5585472
The ADC is configured with ACX enabled, CHOP enabled, Gain=1 and bipolar operation.
I am using these voltages to power the ADC:
|A_GND = D_GND||0||V|
|REFIN+ = A_VDD||5||V|
|REFIN- = A_GND||0||V|
When I put 0 kg weight on the loadcell, the digital value I get is around 13974xxx. Is it coincidence that this is almost the same value as the offset calibration coëfficient + full-scale calibration coëfficient (8388608+5585472=13974080)?
My question is, which statement for conversion does apply to the ADC, because it seems to me that they can't both be true at the same time. Maybe I am missing something? Can somebody please enlighten me?
Thanks in advance