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AD7492BRUZ referencing

Hi!

The AD7492 datasheet says that the internal 2.5 V reference is available for external referencing. The EVAL-AD7492SDZ User Guide showing the connection of REF OUT with +input of the AD8021AR what have typical Input Bias Current 7.5 uA.
I want to connect the voltage divider (750 kOhm+32 kOhm) to the output REF OUT of the AD7492BRUZ and join the midpoint of the divider with a non-inverting input of the AD8066. Could this load affect the AD7492BRUZ?

  • Hi Regwer,

          

       The AD8021 in the AD7492 evaluation board is buffered to connect to external circuit and this will give enough current drive to  the external circuit. Do you mean putting a resistor a 75Kohm and 32Kohm between REFOUT and AD8021? Where is AD8066 connected? If you have a schematic to have a better understanding, please share.

     

    Regards,

    Jonathan

  • Hi,

    I'm not trying to modify the evaluation Board, and am upgrading my device. I attached shematic fragment with a divider, which I wrote   

  • Hi Regwer,

       Thanks for sharing. As I mentioned, the performance of AD7492 specification is not guarantee when placing resistor right after the REFOUT. The Evaluation board has placed a buffer on the REFOUT, this is to have enough current drive on the next stage of the external circuit and

       I recommend to buffer the REFOUT before using it on the external circuit.

    Regards,

    Jonathan

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