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Original question:

TUSB8020B: What happens when USB HUB detect the overcurrent?

TUSB8020B: Over-current event

Yen Nee Lee
Prodigy 110 points
Part Number: TUSB8020B

Hi,

With respect to the question from below thread:

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/600538/tusb8020b-what-happens-when-usb-hub-detect-the-overcurrent

With PWRCTLx/BATENx active high and charging not supported,

1. When over-current event happen and OVERCURxZ is pulled low, the BATENx will be disabled. Correct?

2. When above event happen, the hub will set the overcurrent status in its internal USB hub status register. May i know which register is this referring to? And can it be accessed by OTP?

3. Does the BATENx auto recovers (assert high) after OVERCURxZ is no longer pulled low when the USB load is removed?

 

  • 0
    TI__Guru 60865 points

    Hello Yen Nee Lee,

    1. Yes, this is correct.

    2. The internal register is reported to the host by the Status Change Endpoint, which is part of all USB hubs.  It is defined in Chapter 11.12 of the USB 2.0 specification (you can download the full specification from usb.org).  This register is not accessible by OTP or I2C.

    3. Yes, BATEN will auto recover after OVERCURxZ is no longer pulled low.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 110 points

    Hi,

    Is it correct to say that the status information, change information and control information is accessed by host via the hub's upstream DP & DM lines?

  • 0 in reply to Yen Nee Lee
    TI__Guru 60865 points

    Yes, but there is also a status change endpoint that reports from the USB 3.x portion of the hub too.  An overcurrent event would be reported on both USB 3.0 and USB 2.0 hub instances. 

    Regards,

    JMMN