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TUSB2046B: "USB Device Not Recognized" error whenever the USB cable is plugged in

Naser S.
Genius 11605 points
Part Number: TUSB2046B

Team: Customer have produced thousands of boards in different products using the TUSB2046BVF. While testing a new run of boards with the same parts and board design that has worked in over 100 shipped products, they are now getting a "USB Device Not Recognized" error whenever the USB cable is plugged in to the product. In Device Manager, the USB Hub is showing, the HID-compliant device for our application, and one Unused Port. Two other unused ports on the hub are showing as "Unknown USB Device" and giving an error. The pins on the chip for the two unused ports are not brought out to connect to anything.

The error will be an issue for our customers and create customer calls. I can send screen caps of the error and the schematic. Please advise. Thank you.

  • 0
    TI__Genius 11605 points
    Follow up:

    I see no mention of how to terminate the unused downstream ports in the datasheet. Customer did some research Wednesday and he did see in the forum the downstream ports need to have 15K ohm pull-down resistors. I don’t understand why the first 150 boards of the exact revision and design did not have the problem without the resistors. We still have some stock of the first 150 boards and the design is ok and never fails. The last run of 50 boards is where the issue is occurring.


    Questions:

    1. Any ideas of what to look for in the USB hub circuit to salvage the last run of 50 boards?

    2. Would you be able to send a schematic of the internal circuitry of the downstream ports?

    3. Do you know if something changed internal to the USB hub chip?

    4. Do certain date coded hubs initialize differently?

    Thanks again,
  • 0 in reply to Naser S.
    TI__Guru**** 176811 points
    Naser

    TUSB2046B is a mature design, no design change has been done to the TUSB2046B.

    When unused ports being terminated with 15K pulldown, did it resolve the "USB device not recognized" issue?

    Please go ahead and send me the schematic, and if possible, USB log file between host and hub, and between hub and device.

    Is hub self powered or bus powered? How about the device, is it self-powered or bus powered?

    Have you checked the thermal pad soldering of TUSB2046B and make sure it has good coverage?

    Thanks
    David
  • 0 in reply to David (ASIC) Liu
    TI__Guru 60870 points
    Hi Naser,

    Is there any update on this issue?

    Regards,
    JMMN