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TPS25751: Device will not negotiate PD Source - Does not get Plug Connected indication

Michael Loh
Prodigy 10 points
Part Number: TPS25751

Tool/software:

Our project we are using the TPS25751S in an application where we will generally be USB PD Source, but need to detect when plugged into a PD Source. The TPS25751 is perfect for our application, but we have had issues to get it start to start to provide power.

We know the device is patched and we can explore all the registers. All looks correct, however we cannot seem to get it to detect plug which we expect is the required step for the device to allow source power.



No matter what type of USB C plug we plug, we just cannot get it to detect the cable.

1. Is there a known plug detect issue?

2. Is there an additional step required to enable the USB PD Source mode?

3. Should I expect to see a voltage on the CC1 or CC2 line?

  • 0
    TI__Mastermind 29882 points

    Hi Michael, 

    Thank you for reaching out!

    A couple clarifying questions about your application:

    1- What is the maximum sourcing capability? 

    2- Is the TPS25751S being paired with a battery charger? What is the end-application?

    3- Could you provide the json configuration used in conjunction with your board?

    4- My understanding is that the device is unable to source at all? What downstream devices (sink) have you tested with?

    You should expect to see voltages on the CC lines (depending on orientation of the cable) in order to establish PD communication. 

    Best Regards, 

    Aya Khedr 

  • 0 in reply to Aya Khedr
    Prodigy 10 points

    thank you for the reply.

    Actually we discovered out issue.

    We have placed ESD protection on CC lines in our implementation. The ESD diodes had a breakdown on anything less than 1V meaning that some CC management would be grounded when should have a voltage. The CC exchange failure was causing the PD controller to fail negotiation.

    Removing the ESD diode allowed to work. We are getting expected performance now.

    We will change design to have more appropriate ESD diode.