I am evaluate AD7982 performance with AD7982 evaluation board with Eval-SDP-CB1Z communication board. But the reading seems not correct.
Case 1: Without any input, DC reading seems correct. Its output due to zero differential input should be zero too. But Reading is 2.501V(first photo). IN+=2.5V, IN-=2.5V.
Case 2: Vin+=3.5VDC (1VDC overlap on 2.5V VCM), Vin-=2.5VDC (actually no input). Output reading should be 1V. But actual reading is around 3V. (second photo). IN+=3.5V, IN-=2.5V.
Case 3: Vin+=1.5V (-1VDC overlap on 2.5V VCM), VIN-=2.5VDC (no input). Output reading should be -1V. But actually reading is near 2V. (3rd photo). IN+=1.5V, IN-=2.5V
We plan to use AD7982 to measure DC current in our application. Last photo is the board set up. Could any one help on this?