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TPS25730: trouble self made test board with TPS25730D

Georgi Smilyanov
Prodigy 30 points
Part Number: TPS25730

Tool/software:

Hello Guys,

we made ourself a board to test the TPS25730D. We are using for sourcing Lenovo USB-C PD Device 65W.

After connecting the source device the pin cap_mis toggles. We measure 5V "PWM" Signal 50/50 duty on the VBUS_IN Port.

Could you please review our schematic, if we connected something wrong?

Our ADCIN configuration as below:

I uploeded the PDF with the schematic

RPE_uC_PS_V20.pdf

Thanks for you speed response in advance!!!

Georgi

  • 0
    TI__Mastermind 37855 points

    Hi Georgi,

    There could be a couple things going wrong, but I would start here first.

    Fault in should be pulled up to LDO3v3 through a weak pullup (10k or 100k), otherwise the part will disable on power up if it sees the Fault_in pin in a low state.

    Let us know if this fixes your issues. I didn't see anything else in the schematic that would cause obvious issues.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    Prodigy 30 points

    Hello Chris, thanks for the fast answer. My device starts now. I can measure 15V on the output , but cap_mis signal is still toggling. What can be the reason for this behavior?

  • +1 in reply to Georgi Smilyanov
    TI__Mastermind 37855 points

    Hi Georgi,

    Do you have any way to obtain a PD log? A decoded trace log of the CC line communication? This would be the best way to understand why the caps mismatch pin is toggling.

    In general, the Caps mismatch pin toggles if the adapter offers less power than the minimum power calculated from the ADCINx resistor configuration for the compatible PDOs

    From your settings, I think the minimum power would be set to 45-W, but you limit the TPS25730 to 15-V max so it would be based off of the max power the for the adapters 15-V conract.

    Does the adapter list the supported voltage and current levels? Could you share a picture or a list of the supported levels?

    Something that may be worth testing would be to lower the operating current required and see if the caps mismatch gpio stops toggling.

    Thanks and Regards,

    Chris

  • +1 in reply to Christopher Lim1
    Prodigy 30 points

    Hello Chris, problem solved. Thanks a lot!!!