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AM623: TPS6521901RHBR Power Management IC (PMIC) is not working properly.

yuetong
Prodigy 135 points

Part Number: AM623
Other Parts Discussed in Thread: TPS65219

I am using the TPS6521901RHBR PMIC, where Buck2 is configured to power the peripherals of the AM623 processor. However, the carrier board's PHY chip receives 3.3V power before the PMIC/Core Board starts up. This pre-existing 3.3V back-feeds into the PMIC's Buck2 output rail, causing the TPS65219 to fail its power-up sequence (likely due to the Residual Voltage Check fault). How can I adjust the circuit to resolve this?
 
 

PMIC DESIGN.pdf 

  • 0
    TI__Mastermind 25856 points

    Hi,

    Thank You for using E2E. The TPS65219 PMIC has a built in feature to discharge any residual voltage before executing the power-up sequence and to protect from external backfeeding issues. This PMIC does not have any settings to allow issues like backfeeding. 

    Changing the PMIC settings will not fix the issue. This is a design weakness that must be fixed at the system level so the power solution can successfully execute the power up sequence. 

    Thanks,

    Brenda

  • 0 in reply to Brenda Diaz
    Prodigy 135 points

    What are the risks associated with backfeeding power into an AM62x SoC?

  • 0 in reply to yuetong
    TI__Mastermind 25856 points

    Depending on the specific voltage domains affected by the backfeeding, the issue could violate the SoC sequence requirements, stress IOs that are not fail-safe, affect internal ESD diodes, etc etc. It is challenging to guarantee all the specific consequences when the SoC has not been fully tested and validated for that kind of spec violation faults.  

    Thanks,

    Brenda