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TPS55288EVM-045: Power management forum

Part Number: TPS55288EVM-045
Other Parts Discussed in Thread: TPS55288

Hi TI,

We are attempting to adopt this EVM board with a PD controller to support PD3.1 100W SPR/DRP and fast role swap functions for our project. However, we are struggling with an issue where the VBUS discharge time is too long when the PD is performing a power role swap from sink to source. Even though the DISCHG register (0x06) bit 4 of the TPS55288 has been set to 1, the VBUS voltage still remains at 20V for over 2 minutes.

Would you like further assistance on how to potentially solve this technical issue?

  • Hi Eric,

    May I know how do you do the power role swap since this device is single direction dc/dc converter.

    Have you set the mode at PFM?

    About the DISCHA register, when you set OE=0 and EN high, then there will be about 100mA discharge current from Vout to GND.



  • Hi Bryce,

    I highly appreciate your kind reply.

    You are right. In our project, the TPS55288 always assumes the role of the source side during a power role swap.

    Below are the settings:

    • When VBUS is ON: 06h=0xB3
    • When VBUS is OFF: 06h=0x33

    Unfortunately, regardless of whether VBUS is ON or OFF, we observe a leaking current of about 100mA.

    Additionally, we've measured that the VBUS discharge time is approximately 2 minutes, which is quite long.

    Would you like any further assistance or suggestions on this issue?

  • Hi Eric,

    Thanks for feedback.

    Can you show the schematic and layout of this test?

    May I know how do you test the leakage current when VBUS is on?

    Since I see you set at FPWM mode, can you also show the waveforms of SW1, SW2, Vout and inductor current?



  • Hi Bryce,

    After our internal discussion, I think we are confused about the source and Dual Role Swap circuits. Our USB Docking project must support Dual Role Swap and Fast Role Swap functions. Could you provide an application circuit that supports Fast Role Swap using TPS55288 and TPS25947XX for our reference?

  • Hi Eric,

    Sorry, I don't know how to do the swap circuits using TPS25947xx. It is recommended that you post a new thread about TPS25947xx for suggestions from the experts.

    And if any questions about TPS55288, you can post it here. Thanks.



  • Hi Eric,

    We have not seen an update from you for two weeks, so I assume the questions of TPS55288 are answered.

    I close this thread now. If there is still something open, please reply and the thread will get opened again.

    If you have any other question or of the thread has been locked, please open a new one.

    Clicking the Resolved Button also helps us to maintain this forum.

    Best regards,

    Bryce Xun