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DP83867 Layout Guidelines

Zhou Fang67
Expert 4250 points

Hi Expert,

Do we have layout guidelines for DP83867 1000M Phy? Especially for impedance matching etc...

We have a TI design with DP83867 with some guidelines, but it does not go to details. Anything with more information?

Thanks a lot.

Zhou

  • 0
    TI__Mastermind 18425 points
    Hi Zhou,
    There are certain layout practices that are mentioned in the datasheet. I can point a few down here;
    • No metal beneath the magnetics on any layer.
    • Signal traces should have reference planes. There should be no breaks in reference planes.
    • Single ended traces should have 50ohm impedance and Differential traces should have 100ohm differential impedance.
    • Power supply decoupling capacitors for the PHY should be placed physically close to the device.
    • MAC-PHY signal traces should be length matched. However it is not required for TX traces to be matched to RX traces.
    • PMD signal traces should be length matched between MAC-Magnetics and Magnetics-RJ45 connector.
    • For improving immunity, it is recommended that Earth ground and System ground be separated from each other. Ideally, system ground should stop at magnetics. Earth ground should be restricted on the RJ45 side of magnetics.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    TI__Expert 4250 points

    Hi Aniruddha,

    Thanks a lot. If there is an app note, then it will be good.

    Cusotmer needs to route 10cm for RGMII, in datasheet, 6 inches can be supported. Is there any sepcial notifications for 10cm trace length?

    Zhou

  • 0 in reply to Zhou Fang67
    TI__Mastermind 18425 points
    Hello Zhou,

    There are no special requirements for 10cm trace. Please refer to the same guidelines.

    -Regards,
    Aniruddha