Part Number: ADS5527
We realized a board that integrates several ADS5527. At the moment the board does not work well (it seems that the output of the ADCs is always zero). We suspect that the problem is related to the analog input at pins INP and INM. In fact we are feeding the ADC with a differential signal with no DC component (there are DC blocking capacitors on the input analog lines just before the ADC inputs INP and INM).
The ADS5527 datasheet at page 32 say "The INP and INM pins have to be externally biased around a common mode voltage of 1.5V available on VCM pin 13. For a full-scale differential input, each input pin INP, INM has to swing symmetrically between VCM+0.5V and VCM–0.5V, resulting in a 2-VPP differential input swing".
Unfortunately in our design we are not using the pin VCM (it is connected to ground with two capacitance).
Do you think that our problem is related to the wrong input signal (no DC component)?
If yes, do you have a suggestion to solve the problem?
PS. I've added an image of the connection scheme used to integrate the ADS5527.
