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connecting bipolar input to CN0209 (EVAL-CN0209-SDPZ) board

Question asked by ANJUM on Sep 3, 2015
Latest reply on Sep 4, 2015 by Brandon

Hello Sir,


We have tested the  single input voltage  or unipolar mode in EVAL-CN0209-SDPZ board by giving 0 to +10v and 0 to -10v separately and we received the readings correctly. While testing the single input voltage mode , we gave the connection as said in the Figure 2 in circuit note of CN0209 (or please refer the File1 and File2 attached).

Now we want to test the  bipolar or differential input voltage using the EVAL-CN0209-SDPZ board.We made a similar circuit of CN0209 in a bread board and we gave the input connections as said in the figure2 of the  circuit note of CN0209(or please refer the File3 attached) from a yokogawa  handy mutifunction calibrator CA71 ( just connecting inputs at JX-2 and JX-3 and didnt gave any connections to agnd of the main board.). But we found the AD8275 getting damaged , even for an input voltage of 1V from the source. How can we correctly provide the differential voltage as said in figure2 of the circuit note of CN0209? Is it necessary to provide the AGND, during differential input measurement? Will it work correctly, if we  provide an input as shown in file4??