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TUSB8044A: TUSB804xx Host Controlled Per Port Power Reset

Brett Padfield
Prodigy 10 points

Part Number: TUSB8044A
Other Parts Discussed in Thread: TUSB8042A

Hi, I'm currently designing a USB 3.0 hub that requires host-commanded per-port power cycling. I've been reviewing the TUSB8042A datasheet but I'm having trouble finding a clear answer on a few things:

Is there a native mechanism to toggle per-port VBUS from an upstream host command, either through the port control pins or overcurrent pins? Is external hardware beyond a standard power switch IC required to achieve this? Does TI offer any hub IC that supports this natively without an external MCU?

I want to make sure I'm not missing an obvious use case or recommended reference design before committing to an architecture. Any guidance or application note references would be appreciated. Thank you.

  • 0
    TI__Guru**** 162151 points

    Hi Brett:

       TUSB80xx hubs do support power switching for individual downstream port:

    1: FULLPWRMENT  low to enable power switching.

    2: GANGED pin low to enable individual power switching mode for each port.

    3: PWRCTLx is used to enable or disable Vbus switch .

    4: Vbus switch FAULT pin is connected to hub OVERCRN pin.

    5: once overcurrent happened, FAULT pin and OVERCUR pin will go low.

    6: Once hub detect PVERCUR pin goes low, PWRCTLx will be low to disable vbus switch.

    7: PWRCTLx  will keep low until overcurrent issue cleared.

        Is this feature meeting your design goal?

    Best

    Brian

  • 0
    Prodigy 10 points

    Thank you for the clarification on the overcurrent and fault detection behavior. My question is specifically about whether I can control the PWRCTLx pins independently of the overcurrent protection logic — essentially overriding or bypassing it when needed.

    What I'm trying to achieve is host-commanded per-port VBUS switching: the ability to send a command over the upstream USB port and have the hub toggle a specific port's power on or off on demand, independent of any fault condition.

    A few specific questions:

    Is there any onboard logic or register in the TUSB80xx that allows runtime host control of PWRCTLx independent of the overcurrent protection state, or any other pin that could serve this purpose?

    If not, is there a recommended external hardware approach alongside the power switch IC that would enable this without a captive MCU on a downstream port?

    Is host-commanded per-port power switching achievable on this device at all without an external MCU?

  • 0 in reply to Brett Padfield
    TI__Guru**** 162151 points

    HI Brett:

       From our system, host command can  control power switching PWRCTL if  in individual mode.

    Best

    Brian

  • 0 in reply to Brian Zhou
    Prodigy 10 points

    Thank you Brian, that's very helpful. Could you point me to any documentation or reference on how the host actually issues that command? Specifically:

    Is this done via a standard USB hub class request, or is it a vendor-specific control transfer?

    Is there any host-side software or driver work required, or is this accessible through standard OS USB hub APIs?

    Is there an application note or section of the datasheet that covers the host command interface for PWRCTL in individual mode?

    I'm trying to understand the full stack from host software down to the PWRCTL pin toggle.

  • 0 in reply to Brett Padfield
    TI__Guru**** 162151 points

    USB3.2 spec has all information to control downstream port power,

    SetPortFeature (PORT_POWER) is the command to control downstream port power.

    Regards

    Brian