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AD7764 Rbias stay at zero voltage event MCLK is running, and all supply are feeded.

Question asked by on Jul 27, 2017
Latest reply on Jul 31, 2017 by jcolao

I'm using AD7764, it working fine with some of my board, but there is one board it did not work for some reason. I cannot figure out the issue with it. I would like had some suggestions only what to checking for figure out the issue on the board. The board using AD7764 have 5V supply for Analog, and 2.5V for Digital. 4V Reference bias. I had replace the IC, check all the supply voltage pins, Vref pin. The build-in diff-opamp seem to work but did not center at 2V on the output. The Rbias pin always stay at 0V (where it should be 4V as the working board).