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TUSB546-DCI: Do I need this device, how to know which way to set FLIP

Piers
Prodigy 10 points
Part Number: TUSB546-DCI
Other Parts Discussed in Thread: TPS25810

Tool/software:

Hi,

I'm trying to use a TUSB546 to send USB 2.0, USB 3.1 and a single DisplayPort lane (one P/N pair with DP1.4) to a type C receptacle. This is a source only device, also using a TPS25810 to send up to 3A at 5V. I hadn't planned to need a PD device. For some context, this is on an AMD (Xilinx) Zync UltraScale+ device. One of the GTH transceivers is handling USB and another handles DisplayPort. On their development board these are separate ports.

Reading through the configuration on the datasheet is proving confusing. I'm looking at section 8.3.2, comparing the two figures:

Whether my DisplayPort ends up on TRX1 or TRX2 depends on whether FLIP is HIGH or LOW. How will I know which way to set this control pin?

Say the cable is inverted at the sink end, something will have to compensate. Since the sink is the receiver, the surely that would have to be the device which switches? Then if so, does the source even need a multiplexer, or could I just wire the DisplayPort lane and USB to one each of the lanes?

Appreciate that's quite a few questions but it'd be nice to know if I really require this device or that I'm adding complexity for no reason.

Thanks :)

  • 0
    TI__Mastermind 38635 points

    Hello,

    Piers said:

    Whether my DisplayPort ends up on TRX1 or TRX2 depends on whether FLIP is HIGH or LOW. How will I know which way to set this control pin?

    Say the cable is inverted at the sink end, something will have to compensate. Since the sink is the receiver, the surely that would have to be the device which switches? Then if so, does the source even need a multiplexer, or could I just wire the DisplayPort lane and USB to one each of the lanes?

    Typically, the PD/CC controllers between both the host and the device boards will communicate over the CC lines to determine power delivery and orientation of the cable. Once these have determined the orientation, the PD controller, like the TPS25810 in this case, will communicate to the TUSB546 what the orientation of the cable is via the POL pin, which should be connected to the FLIP pin of the TUSB546. This will help the TUSB546 ensure the DP and USB lanes are correctly routed to account for the orientation of the cable.

    Typically, for a DP alt-mode configuration, yes, both a PD controller and a mux/redriver-mux are needed to ensure proper functionality.

    Please let me know if you have any questions or need any clarification!

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 10 points

    Hi Ryan,

    Thanks, this is super helpful. Somehow I'd missed the output control signals from the TPS25810 - I only had it configured for power delivery. This takes care of the FLIP pin as it can be wired to POL on the TPS25810.

    One control signal that seems to be missing (output from TPS25810) is for telling the TUSB536-DCI whether to send DisplayPort at all. Can I leave the CTL0 and CTL1 high even when it's a USB only connection? Or do I need a different device from the TPS25810 to get this all working seamlessly?

    Thanks, Piers

  • 0 in reply to Piers
    TI__Mastermind 38635 points

    Hi Piers,

    We've got some different reference schematics or schematic guidelines, I would recommend looking through those:

    I believe you can pull the pin up, per the Schematic Checklist, however if you are using I2C, you can use HPD instead.

    Thanks,

    Ryan