I am having trouble getting the ADN8834 to work as expected, and the cause appears to be coming from the Chopper1 amplifier. I am controlling the temperature by applying various voltages on the IN2P pin and OUT1 locks to this voltage; however, it does not match the relationship given by the equation for OUT1 in the datasheet. More specifically, increasing TEMPSET appears to decrease the temperature. I have tried to replace the thermistor with different resistors, and the OUT1 voltage increases as the resistance increases, which doesn't agree with the equations provided for calculating OUT1. The related component values that are being used and the measurements obtained by changing the resistance are given below.
I have also used the ADN8834CP-EVALZ board and have gotten a similar response.
I tried to test the functionality of the amplifier by connecting it as a buffer (removing R,Rx,Z1, and replacing RFB with a short), but when applying 1.247V to IN1P, OUT1 is equal to 350mV.
I would appreciate any help I could get on understanding why the ADN8834 is not performing as expected.
Thank you in advance.