ADUM4190 applicaion issue

Hi ADIexpert

I would like to use the refout1 of ADUM4190 as a voltage reference to my other circuits in the schematic

I connected the REfout1 to the non invert pin of a TL074 to build a voltage follower without attaching any loading on the output of TL074 .

however , the ADUM4190 is damaged after I did this

may I know if this application is ok for ADUM4190?

I don't understand what went wrong if I did this, there is not a lot of description on REFOUT in the datasheet except capacitance limitation ?

thanks

Ken

  • 0
    •  Analog Employees 
    on Nov 23, 2020 3:53 AM 1 month ago

    Hi Ken:

    ADuM4190's REFOUT can not source too much current (10's of uA) but considering TL074's input resistance is very high. This application is OK. 

    Have you ever capture the waveform on REFOUT1 when this damage appear? 

    Regards

    Chris

  • Hi Chris

    yes, please see the picture below

    as you can see from the green waveform, the refout1 steadily output 1.225V  in the first place and after the while the waveform was distorted.

    in this measurement, I didn't even connect the refout1 to TL074 but only attached  the probe on the pin

    I really don't think that probe will make any sinking current to refout1 as well as high imedance input of the Opamp

    any idea or more related document about refout1 is appreciated

    thank you

  • 0
    •  Analog Employees 
    on Dec 1, 2020 7:42 AM 1 month ago in reply to Kencheng

    Hi Ken:

    It is strange to see such a failure. Actually in a lot of experiment, we monitor Vref. 

    could you please share the full application circuit?  you can send it to me via chris.qin@analog.com 

    regards

    Chris