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TPS25763-Q1: How to switch USB mode/DP Alternate mode

Youhei Miyaoka
Expert 3865 points
Part Number: TPS25763-Q1

Tool/software:

Hello team,

I could not understand how to set PD negotiation from the TPS25763-Q1 data sheet, how do I switch between normal USB mode and DP Alternate mode?

[PD Negotiation]
Can the TPS25763-Q1 negotiate PD with device connected via USB?
And is the negotiation configurable in I2C?

[Entry trigger to DP Alternate mode]
When the TPS25763-Q1 is operating as a power source and normal USB DFP, can it send command to enter DP ALT mode at any time?

[Exit trigger from DP Alternate mode]
When the TPS25763-Q1 is operating as Power Source and DisplayPort Sink, can it send command to exit DP Alternate mode at any time?
Or it can only do by DisplayPort Source side?

Regards,

Youhei MIYAOKA

  • 0
    TI__Genius 10825 points

    Hi Miyaoka san,

    Once the 763-Q1 is flashed with firmware configured to support alt mode, it will do the entry process on it's own.  Everything PD related, including alt mode entry/exit, is done over the CC signal of the USB connection.

    When a device connects, the port will initially provide 5V.  Then, based on PD communication over the CC lines, the voltage/current limit may be negotiated to a new value.  Once the voltage/current has been negotiated, there is a series of PD messages used to enter alt mode.  The source and sink need to agree that they both support DisplayPort, along with which DP signal will be assigned to which USB pin.

    For exiting Alt Mode, the DFP (data host) could issue an exit command, but the UFP (data device) cannot.  99% of the time, alt mode exited simply by unplugging the cable.

    This document is slightly out of date, but see page 4 for some details: https://www.ti.com/lit/wp/slly021/slly021.pdf

    Regards,
    Eric