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ISO7742-Q1: leakage in ISO77xx Input coming from BQ79616-Q1

AnBer
Mastermind 28880 points
Part Number: ISO7742-Q1
Other Parts Discussed in Thread: BQ79616-Q1, ISO7742

Team,

Here is the background:
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1056675/bq79616-q1-leakage-over-the-uart-tx-when-in-shutdown-mode-to-the-iso7742-q1-in-pin/3915592

-Can the EN (on the IN side) be used to prevent leakage in the ISO77x coming from the BQ79616-Q1?
-Do you have some design suggestion to prevent this?
I can provide the schematics off-line.

Thanks in advance,

A

  • 0
    TI__Mastermind 49415 points

    Hi AnBer,

    Thanks for reaching out and for providing the background.

    The EN pin is to enable or disable the outputs that share the same GND as EN pin. The input pins do not have enable controlled and are directly driven. Since there is an ESD bypass diode between IN to VCC, applying voltage to IN when VCC is not powered will end-up powering the isolator. 

    The best way to address this issue to follow what Taylor had suggested in your BQ device post. I am not sure what approach is used to disconnect power to VCC of ISO7742, the same approach can be used to disconnect the IN pin from BQ device as well. I hope customer will consider implementing this, thanks.


    Regards,
    Koteshwar Rao