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DP83848Q-Q1: PHYTER Transformerless Ethernet Operation

Daniel Wang (auto)
Expert 5160 points

Part Number: DP83848Q-Q1

Hi team,

My customer is checking the possibility to replace the transformer with caps for 100BASE-Tx.

According to the application note attached, the safe distance for this kind of topology is < 1 meter.

Unfortunately this is not the case for our project. The distance is longer in car.

I would like to know how is the performance if the distance is longer and which test shall be performed to verify the impact?

Since 100BASE-Tx is used for programming in our project, I suppose certain degrade of performance is acceptable.

snla088a.pdf 

BR,

Daniel

  • 0
    TI__Guru**** 191231 points

    Daniel

    The comment in section 2 is a general comment and recommends that network designs utilizing non-typical topologies be verified at the specific application level. If you look at section 7 validation result of the app note, for the bit error rate tests conducted, error free operation of the transformer-less circuit was obtained up to 100 meters in 10 Mb/s mode and in 100 Mb/s mode. Would this meet their requirement?

    Thanks

    David

  • 0
    Prodigy 50 points

    Hello David,

    Thanks for your feedback.

    For the following from section 7, may I know what does this imply?

    "Other IEEE tests, which are designed to simulate worst-case cable loading, did not pass, thus supporting the recommendation to use short distance configurations in non-typical transformerless applications."

  • 0 in reply to Rong Wang
    TI__Guru**** 191231 points

    Hi,

    Two tests are performed, standard IEEE compliance testing as well as bit error rate testing.

    For standard IEEE compliance testing, as the app note pointed out, the transformer-less design did not pass, thus supporting the recommendation to use short distance configurations in non-typical transformer-less applications.

    But if you don't care about passing the compliance testing, and just focus on the bit error rate, then error free operation of the transformer-less circuit was obtained up to 100 meters in 10 Mb/s mode and in 100 Mb/s mode.

    Thanks

    David