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TUSB4041I: Overcurrent Protection Scheme

Leo Rodriguez
Intellectual 945 points
Part Number: TUSB4041I
Other Parts Discussed in Thread: TPS2561,

Hi USB Team,

One of my customers is looking to implement an overcurrent protection scheme similar to what's depicted in Figure 31 of the datasheet. I have a couple of question regarding implementation and internal behavior during such an event:

1. Once an overcurrent event is detected by the TPS2561, the fault pin will drive the appropriate OVERCURxz pin low (correct?):

Does the TUSB4041 automatically disables the appropriate port?

TUSB4041 notifies the host of the overcurrent event and the host sends a comment to disable the port?

In this case, how would this be configured?

3. How does the host gets notified of such an event?

Thanks 

Leo

  • 0
    TI__Guru 60870 points
    Hi Leo,

    1. The TUSB4041 will disable the power on a port while it is reporting an overcurrent event (not ganged mode) or the TUSB4041 will disable power on all the ports while an overcurrent event is reported (ganged mode).
    2. The hub reports the overcurrent event to the host controller via its USB interrupt endpoint . The host controller will then logically disable port power on the hub.

    Regards,
    JMMN
  • 0 in reply to JMMN
    TI__Intellectual 945 points
    Thanks JMMN,

    If I understand correctly, the TUSB4041i will keep the port disabled (not ganged mode) until the overcurrent event is present. This event is reported by the current-limiting switch.

    - Wouldn't disabling the port eliminate the overcurrent condition?

    If the port is disabled automatically by the hub, what do you mean by "The host controller will then logically disable port power on the hub."

    Regards,
    Leo
  • 0 in reply to Leo Rodriguez
    TI__Guru 60870 points
    Hi Leo,

    USB hubs are slave devices so they while they can turn off the port power output if an overcurrent event is reported, they do not clear the port_power bit in the port status register of the hub. Only the host controller can do that. Once the host controller sends a CLEAR FEATURE(PORT POWER), then the port is powered off until the host sends a SET FEATURE(PORT POWER).

    Regards,
    JMMN