ADAS3022 code to voltage conversion

Tech1,

Your LSB weight is off by a factor of 2.   (2*VREF)/((2^16-1)*0.8) = VREF/((2^15-1)*0.8 = 4.096/(32767*0.8) =  156.25uV. 

That should take care of your factor of two.

Sean 

Sean,

Thanks for that. Your formula does indeed fix the factor of two error.

It seems that all single-ended inputs have to be doubled. Am I right in assuming this is due to the differential structure of the ADC?

Cheers

Tech1,

You are close but the real reason is the output encoding as it is fixed to account for the bipolar range which gives 2x the voltage span but as a consequence the LSB weight is also 2x larger than if you could select unipolar operation.  Later products like the LTC2358 family address this limitation of the ADAS3022 by adding unipolar input ranges in addition to the bipolar input range.   The measurement is still differential but allowable input range is now fixed to positive voltages only.

Sean

Tech1,

You are close but the real reason is the output encoding as it is fixed to account for the bipolar range which gives 2x the voltage span but as a consequence the LSB weight is also 2x larger than if you could select unipolar operation.  Later products like the LTC2358 family address this limitation of the ADAS3022 by adding unipolar input ranges in addition to the bipolar input range.   The measurement is still differential but allowable input range is now fixed to positive voltages only.

Sean

Thanks Sean. That's very helpful.