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ADA4938 common mode setting

Question asked by julian_e on Feb 18, 2016
Latest reply on Mar 21, 2016 by julian_e

Hello,

i am confused about the common mode voltage setting of ADA4938 differential OpAmp. As mentioned in the datasheet we would like to set the output common mode voltage via OCM input and an external resistor devider. The OpAmp has dual supply (+/- 5V) and is configured as single ended to differential converter. Should the resistor devider be referenced to ground or -5V? In the datasheet it is mentioned that the ADA4938 has an internal devider. What are the values? How can i calculate a proper external devider if i dont know the internal values?

We tried different external resistors but it seems that the common mode voltage is different with every ADA4938.

Can someone give me an advice?

 

Best regards.

Julian

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