Hello,
We did some investigation about our offset appearing and disappearing :
It was indeed the Vref over voltage we put on the ADS1246.
Vref = Vrefp-Vrefn should not exceed Avdd-Avss-1V, which in our case was not achieved.
Regarding the die in place on the board, there seems to be a limit over which the ADC begin to leak few µA to Vains.
In our try and error test, this limit seems to be 3.5V for Avdd=3V.
I am pretty sure that some dies have lower limit. And rising temperature is even reducing more this limit .
Which means that with some dies, at some temperature, the max limit before leakage can be 3V : and tha tha!! µA over thousands ohm sensors get you to few annoying mVs.
We are going to change all our analog plan to meet the specs on Vref.
Hope this will help further users.
Quentin
