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TUSB2077A: Failure after long working time

zhang ping
Genius 3835 points
Part Number: TUSB2077A

Our test board uses a Ti HUB chip: tusb2077a. There is a problem found in the test these days. Please ask. When the circuit board is continuously tested for dozens of hours, the USB does not recognize, the test is interrupted, and the corresponding indicator on the board is abnormal. There are three groups of indicator lights on the board, which are chip pin signals: hubcfg, portpwr, portdis. In case of abnormal phenomenon, hubcfg and portpwr are displayed as off status indication. I don't know what causes it. Please help me to analyze it. The following is my schematic design. The power supply is self powered on the board：

  

 

   TUSB2077A_SCH.pdf
  • 0
    TI__Guru 60870 points

    Hello Zhang,

    Do all the hubs in the schematic show the same behavior?  The schematic look acceptable.  The pullup on the upstream DP should be close to the hub, not on the other side of the series resistor, but that may not explain the behavior.  Do you get any errors reported on the USB host?

    Regards,

    JMMN

  • 0 in reply to JMMN
    Genius 3835 points

    The circuit is extended to the second level (3 * usb2077) through the first level hub (usb2077). Now the PC is connected to the first level hub, and the PC does not recognize the device. The subsnd indicator is always red, and it is also red when it can be connected normally. Can you help me with the analysis? Are there any special requirements for power on sequence? Is there any special requirement for reset sequence? After the initial communication is successful, is the chip dormant due to no communication for a long time?

  • 0 in reply to zhang ping
    TI__Guru 60870 points

    The hubs are in suspend, which will occur if there are no devices connected downstream.  Which port is the device connected to?  Does the system work initially and fail curing cycle testing?   Can you probe the DP/DM lines between the host and the top level hub and see what the line states are?