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ADS8681EVM-PDK: PHI board 3.3V output does not turn off immediately.

Part Number: ADS8681EVM-PDK
Other Parts Discussed in Thread: ADS8681


I am using the 3.3V from the PHI board to power another board (Test Board) which is connected to PHI board's signal source. When I connect USB cable of ADS8681 and open the software, this 3.3V is supplied to the Test Board. However when I disconnect the USB cable, the 3.3V reduces to 0 very slowly damaging a transistor in the board. 

Can you please assist me on how to solve this and let me know whether it will be possible to cut off the 3.3V from PHI board immediately before disconnecting the ADS8681 board from laptop. 

Thank you.

  • Hi Maheedh,

    The PHI controller board is only designed for the EVM board for ADC evaluation purpose, we do not recommend to use the PHI card for other purpose because the power supply current from the PHI card is very limited and it's possible to damage the PHI card when it's used for other circuit board.

    There is no way to cut off the 3.3V power supply from the PHI card because there is no switch on that, however you can add a switch on your test board, or you may have to check if the capacitance load on your test board is too high for the 3.3V supply.