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DP83TC812R-Q1: ESD protection

Daniel Stekelenburg
Prodigy 10 points
Part Number: DP83TC812R-Q1


Tool/software:

Hello,

I would like to include additional ESD protection at my ethernet physical but find it difficult to select the right TVS diode. The internal protection is not adequate for my application as I occasionally see damaged physicals. As the datasheet recommends, I would put it right at the MDI pins but how do I guarantee that the common mode pulse is sinked by the added TVS instead of the internal protection on the PHY? I can't find any details regarding ESD protection in any TI provided document to help me with this problem.

I am currently looking at the Littlefuse AQRV05-4HTG. Do you think this will give me the appropriate protection? Hope anyone can help me out, thanks!

  • 0
    TI__Mastermind 27212 points

    Hi Daniel,

    We have included our ESD diode recommendation in SNLA389 , see table 2-1. This has been verified to provide adequate protection against ESD strikes and other transients which may have caused the damage you are referring to.

    Thanks,

    David

  • 0 in reply to David Creger
    Prodigy 10 points

    Hi David,
    working in the same team as Daniel.
    we measure a voltage of over 4V (absolute max rateing of the PHY) to 9V with in a periode of 20µs in case of a Surge (EFT) according to IEC61000-4-5 (no ESD).
    The surge propagates somehow into the signal-area.
    We ask if this is transients are considered as harmfull form TI side?

    Additionally we observe a significant inner resistance drop at the TRD_P / TRD_M PINs after the surge but without noticable change in signal quality and general functionality. Do you have an idea where it may come from in the PHY?

    Can you provide a functional diagram of the TRD_M / P PINs inner circuit?

    Thank you
    Peter

  • 0 in reply to Peter Raab
    TI__Mastermind 27212 points

    Hi Peter,

    Yes, this transient is considered harmful as it is above the absolute max rating for the PHY. See SNLA389 for our recommended ESD diode to protect against such transients.

    Thanks,

    David