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TUSB2077A: Behavior when downstream port detects overcurrent

Conor
Guru 12050 points
Part Number: TUSB2077A

Hi,

Please tell me how the HUB works in the following cases.

・What to do when one of the Hub's downstream ports detects an overcurrent and the Hub disables the power to this port

At this time, if the downstream status is requested from the upper level, how will each port respond to the request for all port status for (Get_Port_status)? The USB Log appears to report abnormalities (overcurrent, etc.) for all ports, not just the corresponding port. Specifically, I would like to know the following:

■Hub response after OVRCUR7-N goes low due to current limit and PWRON7-N changes from low to high when a damaged device is connected to the port connected to DP7, DM7 due to short circuit.

Thanks,

Conor

  • 0
    TI__Guru*** 144745 points

    Hi Conor:

       it depends on how do you set the hub switch by pin 8 either in individual power switch mode or ganged mode.

    based  on your report, hub is in ganged mode.

    Conor said:
    Hub response after OVRCUR7-N goes low due to current limit and PWRON7-N changes from low to high when a damaged device is connected to the port connected to DP7, DM7 due to short circuit.

       If  hub is in ganged mode, when a damaged device is connected to DP7, hub will turn all downstream ports off until you unplugged damaged device and clear the overcurrent condition.

    Regards

    Brian

  • 0 in reply to Brian Zhou
    Guru 12050 points

    Hi Brian,

    Thank you fot your reply.

    Please also let us know about the behavior that the Hub performs on the upstream side.

    Thanks,

    Conor

  • 0 in reply to Conor
    TI__Guru*** 144745 points

    Hi Conor:

        Hub upstream should be still connected, what did you see?

    Regards

    brian

  • 0 in reply to Brian Zhou
    TI__Guru*** 144745 points

    any update?

    Regards

    brian

  • 0 in reply to Brian Zhou
    Guru 12050 points

    Hi Brian,

    Sorry for the late reply.

    Brian Zhou said:
    based  on your report, hub is in ganged mode.

    I have a question about the above.

    Q1. Is "ganged mode" a setting that can be changed?

    Q2. If it can be changed, how can I change it?

    Q3. If it is not ganged mode, what will be the behavior you mentioned in your previous answer?

    Q4. There doesn't seem to be any mention of mode settings such as ganged mode in the data sheet. Are there any documents that mention these modes?

    Thanks,

    Conor

  • 0 in reply to Conor
    TI__Guru*** 144745 points
    Conor said:
    Q1. Is "ganged mode" a setting that can be changed?

      yes

    Conor said:
    Q2. If it can be changed, how can I change it?

    can be changed by by pin 8 

    Conor said:
    Q3. If it is not ganged mode, what will be the behavior you mentioned in your previous answer?

    if not ganged mode, if over current happened, only that particular port got disabled, other ports are still working

    Conor said:
    Q4. There doesn't seem to be any mention of mode settings such as ganged mode in the data sheet. Are there any documents that mention these modes?

    see pin 8 description.

    Regards

    brian