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DP83822I: ESD Protection of TD_M, TD_P, RD_M, RD_P

Patrick Ruf
Genius 4965 points
Part Number: DP83822I
Other Parts Discussed in Thread: TPD4E05U06, , TIDA-00299

Hi,

We plan to make a design based on the DP83822I for Industrial Ethernet. I have studied some designs from TI for example TIDA-00299. In this design I can see a TPD4E05U06 ESD protection device on the TD_M, TD_P, RD_M and RD_P signals. Also there are capacitors (4.7pF) on each of this signals to GND.

Questions:
a) What is the purpose of the capacitors?
b) Is the ESD protection device necessary or does the design pass ESD testing without it? On the DP83822 EVM this device is not populated. Maybe TI can give some more information?

Thanks and best regards,

Patrick

  • 0
    TI__Mastermind 19780 points
    Hi Patrick,

    The ESD rating of the DP83822 is published in the datasheet. The ESD rating in the datasheet is achieved without the use of external protection devices.

    External protection devices can increase the ESD rating, or provide other immunity for the device. In TIDA-299, an external ESD diode is used to increase contact discharge to 12kV.

    The 4.7pf caps on the signal lines is for EMI testing and not related to ESD.

    Best Regards,