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DP83620: what the max differential signal level in copper mode?

Gump
Intellectual 490 points
Other Parts Discussed in Thread: TPD4E1U06, DP83620

Hi,

What the max voltage level for differentia signall in copper mode? So i can set a protect voltage level, and may know if it is the reason of frequently damage.

Thnaks!

  • 0
    TI__Mastermind 18425 points
    Hello,

    The maximum voltage in 10M mode 2.8V and in 100M mode is 1.05V. Please note that these are differential signal voltage levels. The output of the PHY also has a pull up resistor network.

    Are you planning to use something like TVS diodes? Are the protection devices connected between PHY and Magnetics?

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Intellectual 490 points
    Hi Aniruddha，
    Thanks for your time and answer!
    Do the maximum vlotage 2.8V&1.05V is peak to peak ? Is that absolute value? What the TVS do you suggest to use, If protection devices connected between PHY and Magnetics ? As you know, the TVS pretect voltage could not as low as 1.05V.
    Thanks!
  • 0 in reply to Aniruddha Khadye
    Intellectual 490 points

    Dear Aniruddha,

    I am anxiously awaiting your reply. Thanks!

  • 0 in reply to Gump
    TI__Mastermind 19780 points
    Hi gan,

    The recommended protection diodes for our 100base-tx devices is the TPD4E1U06. The most frequent damage to the device from the cable side is either:
    1. PoE circuits that do not have protection diodes and cause surges to the pins when first connected
    2. ESD strikes when cables are plugged in (longer cables can build up more charge)

    The TPD4E1U06 provides excellent protection against these two events. Please read the app notes on placement of the TPD4E1U06 in your circuit. The protection diodes should be between the transformer and the PHY. Do not put the diodes between the transformer and the RJ45 jack.

    Best Regards,
  • 0 in reply to Aniruddha Khadye
    Intellectual 490 points
    Hi Aniruddha,
    Do the maximum voltage of 2.8V and 1.05V are (TD+ to TD-) or (RD+ to RD-)? Or both of them?
    Thanks!
  • 0 in reply to Rob Rodrigues
    Intellectual 490 points
    Hi ,
    Thanks for your suggestion!
    Currently, customer uses SRV05-4, which is simlar to TPD4E1U06, but frequently damage.
    As the maximum voltage is 1.05V @ 100M, does it work when the "Breakdown Voltage" of TPD4E1U06 is 6V ?
  • 0 in reply to Gump
    TI__Mastermind 19780 points
    Gan,

    Is the diode being damaged? Or is the DP83620 being damaged?

    The 1.05V is the AC spec for the pins. This does not have to do with the protection threshold. 5V - 6V protection is what we commonly recommend.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Intellectual 490 points
    Dear Rodrigues,
    It is DP83620damaged.
    I do not understand "The 1.05V is the AC spec".
    Aniruddha mentioned that "The maximum voltage in 10M mode 2.8V and in 100M mode is 1.05V. Please note that these are differential signal voltage levels. " Beside 2.8V & 1.05V, I also want to know the absolute value for differential and single-ended singal.
    Thank you!
  • 0 in reply to Gump
    TI__Mastermind 18425 points
    Hello Gan,

    The TVS diode voltage threshold is kept at level such that normal PHY operation does not accidentally trigger the diodes. The maximum voltage swing of the signal will include the DC pull-up + positive AC voltage swing. For e.g. If DC pull-up of 3.3V is used and the part is working in 10M mode the voltage swing can be 3.3 + (2.8/2) = 4.7V.

    -Regards,
    Aniruddha