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TPS65987D: CC1 & CC2 not communicating

Kevin Connaughton
Prodigy 55 points
Part Number: TPS65987D

Hello,

I have a custom board using tps65987D. When a device is plugged in the 5V is enabled and looking on the CC1 lines you can see some activity when a button is pressed on the Sink EVM board but no response comes from the TPS65987D. 

Due to a fault on the board Drain 1's pad was shorted to GND internally so the traces were cut to isolate it and VBUS1. Could these being isolated cause cc1 to not communicate?

Kind Regards,

Kevin.USB Power Board.pdf

  • 0
    TI__Genius 12700 points

    Hi Kevin,

    Does this mean that your VBUS1 and VBUS2 aren't connected together anymore? This could also cause an issue. 

    Thank you,

    Hari

  • 0
    Prodigy 55 points

    Hi Hari, That is correct. In the current configuration VBUS1 and Drain1 are floating.

    We will re-spin the board unwanted to confirm that it was that that was causing the CC line to not respond.

    Kind regards,

    Kevin.

  • 0 in reply to Kevin Connaughton
    TI__Expert 8680 points

    Hello Kevin,

    I would like to see CC scope trace. Could you please share the same? 

    Thanks

    Prajith

  • 0
    Prodigy 55 points

    Hi Prajith,

    I am not able to re-generate the scope traces as the board is out of my hands at the moment. They were uneventful however. The cc line would sit at 3.3, 1V8 or 0.7V depending on cable orientation and sink connection. When a sink was connected this remained solid, when a request came in from the sink the cc line would briefly drop low before becoming solid again. Looking at the CC line of the EVM I would have expected the CC line to be active even without a sink connected. 

  • 0 in reply to Kevin Connaughton
    TI__Genius 12700 points

    Hi Kevin,

    Prajith is currently out of office, he will be able to support you once he is back next week.

    Thank you,

    Hari

  • 0 in reply to Kevin Connaughton
    TI__Expert 8680 points

    Hi Kevin, 

    For me it looks likes the PD controller is able to establish implicit contract but its not sending Source cap messages to Sink. Are you getting the board sometime soon for further debug? I would like you to check if the the PD controller is able to successfully boot up from the external SPI flash. You can check firmware version on the device after entering debug mode using GUI. Do not connect Sink in debug mode. 

    For the next revision board, yes VBUS1 and VBUS2 should be shorted together. 

    When you say Vbus1 is floating, which Vbus pin is connected to Sink/ Type-C connector? I can see VBUS 1- VBUS2 connection in the schematic. 

    Thanks
    Prajith