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TPS65981: Configuration Commands

Jerry%20Leung
Intellectual 905 points
Part Number: TPS65981

Hi Team,

I have a customer using two TPS65981 in the configuration below, but are running into some issues with configuring the chips.  Could you help provide some insights on the questions below?

We've configured PP_EXTconfig as 101b(PP_EXT configured for Sink (input) and Source (output), but will wait for

SYS_RDY command (SRDY) before closing the switch). However when sending the SRDY command with argument 0b11, the command is rejected and the switch does not turn on. The PD controller is in a sink role, so why does the switch not turn on?

We also want to be able to switch the power path sourcing PP5V after the contract has been made. We've tried to change PDO0NotSourcedbyPP5V0 in TX source capabilities from 1 to 0 in order to switch from EXT power path to 5V power path, but this does not seem to make the switch. What is the fastest way to switch the power path providing PP5V?

Thanks for the help and best regards,

Jerry

  • 0
    TI__Mastermind 36756 points
    Hi Jerry,

    I'm not sure I fully understand the use case here. The TPS65981 is a single port PD controller. You cannot use two TPS65981 devices on the same USB Type-C Port.
    If you would like to change the power path being used, you can do so by writing to the global system config register. However, this would force a disconnect and reconnect on the Type-C port. There is no way to change the power path in TPS65981 without forcing a reconnection.

    Thanks,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 30 points

    Hi Eric,

    We are trying to make a device with two USB Type-C ports and have one TPS65981 control each port. However in the device, they are connected to the same bus after the external FETs.

    Thanks for answering our question about switching power paths. 

    Our other, more pressing question is in regards to the SRDY:

    "We've configured PP_EXTconfig as 101b(PP_EXT configured for Sink (input) and Source (output), but will wait for SYS_RDY command (SRDY) before closing the switch). However when sending the SRDY command with argument 0b11, the command is rejected and the switch does not turn on. The PD controller is in a sink role, so why does the switch not turn on?"

    Thanks,

    - Jack

  • 0 in reply to Jack Ye
    TI__Mastermind 36756 points
    Hi Jack,

    The SRDY Task shall be considered rejected if:
    • PD Controller is not in a Sink role.
    • SwitchSelect == 00b and more than one switch is configured for input (PP_*config == 1Xb).
    • SwitchSelect == 01b and no switch was previously disabled by SRYR and more than one switch is configured with PP_*config == 10b.
    • SwitchSelect == 10b or 11b and the specified switch is not configured for input.
    • The selected switch cannot be enabled for some reason (UVP/OVP or some other fault

    Thanks,
    Eric