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TPS25751: Power Path situation with Re-contract

Hideki Hayashi1
Expert 8390 points
Part Number: TPS25751

Tool/software:

Hi team,

Users concern about whether the internal power path (TPS25751D) will not shut off when re-contract

Condition:

9V/3A sink -> MCU sends different RDO -> TPS25751D sends RDO to PD source -> 5V/3A

Actually customer doesn't observe the power path shut off and see the voltage transistion is correctly done. Could you please explain why TPS25751 can keep the internal power path on during changing RDO? Is there any risk?

Best regards,

Hayashi

  • 0
    TI__Mastermind 30222 points

    Hi Hayshi, 

    Thank you for reaching out!

    I will review and get back to you with feedback by Wednesday.

    Best Regards, 

    Aya Khedr

  • 0 in reply to Aya Khedr
    TI__Mastermind 30222 points

    Hi Hayashi, 

    This is expected behavior when the PD controller renegotiates a contract. An important aspect to consider would be the current draw. 

    According to the PD spec, during voltage transitions, the system should not be drawing >500mA. 

    Best Regards, 

    Aya Khedr

  • 0 in reply to Aya Khedr
    TI__Expert 8390 points

    Hi Aya,

    Customer just understand that TPS25751 follows the PD spec. However, customer doesn't understand how TPS25751 follows the spec.

    Aya Khedr said:
    the system should not be drawing >500mA. 

    On this statement, what will happen when the system draws >500mA during this duration? Does the TPS25751 turns off power path in very short period and turns on immidiately? Customer system will not draw >500mA during this transition, but they wants to understand the behavior.

    Regards,

    Hayashi

  • 0 in reply to Hideki Hayashi1
    TI__Mastermind 30222 points

    Hi Hayashi, 

    The TPS25751 would fail compliance testing if the system draws >500mA during the transition time. 

    The power path behavior on the Sink side might not be affected if the system draws >500mA but this could have an effect on the Source. 

    Best Regards, 

    Aya Khedr