Other Parts Discussed in Thread: ADS131A04, ADS131M08, ADS1278, REF5030, OPA191, LM8261
I implemented the ADS131E08 on a board where I'm measuring signals (IN-P) that range between 0V and 2V. IN-N is tied to ground. I'm using an external precision 3V reference. Note, AVDD is 5V and AVSS is ground. The prototype isn't working properly because my common mode voltage, Vcm, doesn't meet the requirements in the "Input Common-Mode Range" section. My solution is going to be to respin the board with the following changes: set AVDD to 3.3V and set AVSS to -1.7V. I'm leaving my input circuits (IN-P and IN-N) the same and VREFP at 3V. This makes it so my Vcm falls within the required range. The question is do I have to tie VREFN to AVSS? In section 7.3 of the datasheet it shows VREFN as AVSS nominally. It doesn't give a range. Because my input signal is always positive, I was hoping to keep VREFN at ground so that my VREF (VREFP-VREFN) is 3V and not 4.7V which would keep my resolution the same. Appreciate any help.