I have used the AD7190 EVAL board to measure the battery voltage (1.5V), and the battery+ is connected to AIN+ and battery- is connected to AIN- terminals. Please see attachment for details.
I am also using the REF2 that comes with the EVAL board, with the following setting:
Gain = 1
Buffer = OFF
Chopping = OFF
Input: AIN1 and AIN2
FS Bits = 48 (100Hz)
Running the program using Bipolar mode gives me the P-P resolution of 20.2 bits. However, once I changed to Unipolar mode, the resulting P-P resolution becomes 19.2 bits.
Is this expected or is there anything wrong with the input connection/software setting?
Thanks for your help.