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DP83869HM: RGMII-to-SGMII bridge mode

Souvik Sarkar
Prodigy 90 points
Part Number: DP83869HM

Hello All,

This is regarding a custom board wherein we are using the part DP83869HM. We have an RGMII interface on a microprocessor and SGMII interface on a switch. We want to use this PHY as a bridge between the two.

However, the RGMII interface is at 1.8V and the SGMII is at 3.3V. Please find the below query regarding the same:

Does supplying only VDDIO with 1.8V suffice for the same in two-supply mode. Or is it necessary to opt for three-supply mode for the same?

  • 0
    TI__Mastermind 24881 points

    Hi Souvik,

    Let me check with the team. Due to U.S. holiday, I will get back to you next week.

    Thanks,

    David

  • 0 in reply to David Creger
    Prodigy 90 points

    Hello David,

    A very happy new year to you. Please help regarding this. It would be greatly appreciated if you could help with this as soon as possible.

  • 0 in reply to Souvik Sarkar
    TI__Mastermind 24881 points

    Hi Souvik,

    What do you mean by SGMII is at 3.3V? SGMII is LVDS signalling so does not operate on the VDDIO logic level like RGMII does. I am assuming you mean the PHY inside the switch is operating with VDDIO = 3.3V. This will not translate to SGMII voltage, though, where only the differential voltage matters. 

    The DP83869HM can support SGMII input differential voltages from 0.3 to 2.0V, and has output differential voltage configurable between 0.6V - 1.27V (default at 1.1V). This does not depend on VDDIO. Since SGMII is a standard protocol, the switch likely will support the same but please confirm. 

    Either two or three supply mode can be used, but ensure that VDDIO is 1.8V to support the RGMII logic level.

    Thanks,

    David

  • 0 in reply to David Creger
    Prodigy 90 points

    Hi David,

    Thank you for your help. So, as I can understand from your statement, we can use either two or three supply mode in DP83869HM but we need to ensure that VDDIO is 1.8V to support the RGMII logic level. The other end could be SGMII or Copper?

    Is this OK?

  • +1 in reply to Souvik Sarkar
    TI__Mastermind 24881 points

    Hi Souvik,

    Yes, that is correct.

    Thanks,

    David

  • 0 in reply to David Creger
    Prodigy 90 points

    Thanks David for your help. Good Day to you.