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TUSB7320 EVM - ESD/EMI protection

David F
Intellectual 645 points
Other Parts Discussed in Thread: TUSB7320

The TUSB7320 EVM implementation provided ESD protection on all 3 USB pairs, but only supports EMI filtering on 2 pairs. Refer to SLLU146C page 15.

Is there perhaps some undisclosed issue with EMI filtering on the superspeed receive pair?

  • 0
    TI__Guru* 76130 points
    Hello,
    I'm little confused with your question, the EVM has EMI filtering on all the USBSS_TX and all the USB_DP/DM.
    It has ESD protection on all the USBSS_RX.

    The above is kind of standard for USB implementations, depending on your design/requirements, you may or may not include more protection.

    There are not undisclosed issues withe EMI.

    Best Regards
  • 0 in reply to Elias Villegas M.
    Intellectual 645 points

    Hi Elias,

    Not sure how to be clearer. All three pairs on each connector should have both ESD protection and EMI suppression for commercial applications.

    For instance on J1:

    1. USB_D pair (pins 1,2) has ESD protection and EMI suppression via L2.

    2. USBSS_TX pair (pins 8,9) has ESD protection and EMI suppression via L4.

    3. USBSS_RX pair (pins 5,6) has only ESD protection via U25. There is no comon-mode EMI choke on this pair. This presents a conducted EMI issue. Going to the trouble of plugging two EMI "holes" without plugging the third seems odd.

    4. Normally, I would add ferrites to both VBus and Ground as well...

    Does this clear things up?

    Best,

    Dave

  • 0 in reply to David F
    TI__Guru* 76130 points
    Oh, I see.
    You are right.
    At the end of the day this was a designer's choice, but I agree with your comments though, I actually think it could be a typo and the TPD2EUSB device was actually supposed to be on the DP/DM lines.
    I will take this around the table and we will probably update the user's guide.

    Again, the ESD and EMI protection is optional depending on your system, the only required protection is the one on the connector's shield.
    Thank you for your comments.
  • 0 in reply to Elias Villegas M.
    Intellectual 645 points

    Thanks, Elias.

    My main concern was that there might be an issue with the superspeed receiver on-chip that made adding a common-mode choke to the pair problematic.

    Best,

    Dave