• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 32 subscribers
  • Views 125 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83TC812S-Q1: TRD common mode voltage

Timothee TOUDIC
Prodigy 30 points
Part Number: DP83TC812S-Q1

Hello,

For reliability and redundancy purposes, and for very small overall network length (<1m), we would like to switch the TRM lines between 2 targets.

We would then like to know the output common mode voltage of the TRD pins, or at least a value of the minimum and maximum voltage for the two differential pins. If that is not known, we would have to DC-block and re-bias in an additional stage, which is not desirable. Having this data with different VDDIO possible values would be even better.

Thank you.

  • 0
    TI__Genius 17800 points

    Hi Timothee,

    Can you please clarify the sentence "we would like to switch the TRM lines between 2 targets." Does this mean you want to switch the polarity of pins 12 and 13? If so, no concern is needed, as the PHY has auto-polarity detection and correction. Please see section 8.4.11.2 for more information.

    Regarding your second question, the common mode voltage is not characterized. You will need to perform such a measurement yourself.

    Thanks,

    David

  • 0 in reply to David Creger
    Prodigy 30 points

    We would like to switch the TRD lines from one PHY to another, after the CM termination + DC-block, which is why knowing the voltage range on the TRD pins is necessary, in order to choose the appropriate component to perform that switching. This would of course be an unbuffered analog switch. We are aware that this is liable to cause signal degradation.

    These MDI outputs are advertised as VML, is there really no measurement that TI might be able to share, taken directly from the pins of the PHY?

  • +1 in reply to Timothee TOUDIC
    TI__Genius 17800 points

    Hi Timothee,

    This value is not characterized, I cannot provide a measurement. You will need to conduct such testing yourself.

    Thanks,

    David