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TUSB8040A Upstream Port USB 3.0 Rx Long Channel Jitter Tolerance

1859464
Intellectual 575 points
Other Parts Discussed in Thread: TUSB8040A

Hello, 

We are seeing a high percentage of USB 3.0 Rx long channel jitter tolerance failures on the upstream port of product samples tested. The TUSB8040A downstream ports pass on all samples tested. 

1. Does the TUSB8040A upstream port pass the USB 3.0 Rx long channel jitter tolerance compliance test? Is there any Sj frequencies that are marginal with this hub?

2. Has TI compiled a list of USB 3.0 B connectors that are recommended to use (signal-integrity/crosstalk) and also a list of connectors that are not recommended to use (poor signal-integrity/crosstalk)? 

Test Notes:

1. We are using LeCroy SDA 830Zi-A scope with LeCroy PeRT with QualiPHY compliance software, using USB-IF USB 3.0 test fixtures. 

Regards, 

KT

  • 0
    TI__Guru 60870 points
    Hi KT,

    We use a very similar setup in our lab and we pass RX jitter compliance testing with good margin. For many USB 3.0 applications, the problem frequencies are 33 MHz and 50MHz.

    We recommend that customers use USB connectors that have passed compliance testing by the USB-IF. You can find a list of those by going to usb.org -> products and doing a search of USB 3.0 Type B receptacles.

    Regards,
    JMMN
  • 0 in reply to JMMN
    Intellectual 575 points

    Hi JMMN, 

    Yes, our problem frequencies are usually 33MHz and 50MHz, and sometimes 20MHz. 

    We installed the Foxconn USB B connector from the TUSB8040A EVB and observed a significant reduction in bit errors versus our original B connector, but we still have bit errors at 33MHz and 50MHz causing compliance failure. 

    What root causes have you observed to be the most significant contributors to failing upstream jitter tolerance? 

    a. Connector crosstalk? 

    b. Trace cross-talk?

    c. Via cross-talk?

    d. Xtal manufacturer?

    e. Xtal circuit?

    f. Power supply ripple frequency?

    g. Hub power decoupling impedance profile?

    h. Routing the Rx traces on top layer worse than routing them on the bottom layer as was done on TUSB8040A EVB?

    i. Other?

    Regards, 

    KT