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TPD3S716-Q1: USB2.0 Eye Diagram Test

Part Number: TPD3S716-Q1

Tool/software:

Hi team,

My customer Bosch asked if you can help provide some suggestion about the TPD3S716-Q1 USB2.0 eye diagram test results improvement on their board? Thanks

Test Result:

J12-USB2.0-TBOX_Fail.pdf

Best Regards,

Xiaowei Zhang

  • Xiaowei,

    Can you send me the scope capture of the Eye Diagram and layout captures for the USB path in the design?

    The schematic shows everything is correct, but the USB performance is very layout dependent.

    Regards,

    Chuck

  • Hi Chuck,

    Eye Diagram test result:

    J12-USB2.0-TBOX_Fail.pdf

    Layout:

      

    Can you please feedback some comments on their layout?

    Best Regards,

    Xiaowei Zhang

  • Xiaowei,

    The Eye diagram test indicates that the USB signal is significantly bandwidth limited, but does not show any asymmetry that would be indicative of grounding or routing issues and when I reviewed the system routing, I did not see any issues that would be of concern.

    The TP3S316 has a nominal BW of 900 MHz, so it is not inherently the cause of the failure, but it does limit the system bandwidth.

    We have a few places that we can experiment with to see if the BW of the system can be improved.

    Here are the experiments that I recommend you run if possible:

    1.  Change C8212 and C8213 from  5.6pF to 6.8pF.  This will change the matching filter and may improve the system BW.

    2.  Change L8202 and L8203 from 8.7nH to 18uH.  This will change the matching filter and may improve the system BW.

    3.  Combine changes 1 & 2

    These experiments are the thinks that I can think of that may improve the system BW.  If you can run them and then send me the same PDF report as the current system.

    If this does not work, then adding a TUSB211A re-driver after the TD3S716 to recover the BW.

    Regards,

    Chuck