• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 101 subscribers
  • Views 783 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.

DRA829J-Q1: Quad 2.5GBASE-T PHY interface using SGMII SerDes

jars121
Intellectual 635 points
Part Number: DRA829J-Q1
Other Parts Discussed in Thread: DRA829J

Hi TI,

I'm looking at implementing four 2.5GBASE-T networks on a DRA829J, and would appreciate some clarifications if possible.

  1. Table 12-251 SerDes Supported Standards in the J721E TRM (SPRUIL1C) shows the SGMII interface as having both 1.25Gbps and 2.5Gbps bit rates. My understanding is that for SGMII to support 2.5GBASE-T, the baudrate needs to be 3.125Gbaud to deliver 2.5Gbit throughput with 8b/10b encoding. Can you please clarify whether this is correct, and if so, whether 2.5GBASE-T (at 2.5Gbit/s) is supported?
  2. If 2.5GBASE-T is supported at the full data rate, is there a suitable quad port 2.5GBASE-T PHY that you could recommend? I've come across the MaxLinear GPY245 which appears to be suitable, but it provides four SGMII+ interfaces, which seem to be SGMII interfaces that support 3.125Gbaud. Assuming that the answer to question 1 above is that 3.125Gbaud is supported, I imagine this PHY would be suitable and the DRA829J SGMII SerDes lanes would be compatible with MaxLinear's 'SGMII+' interfaces?

Thanks!

  • +1
    TI__Mastermind 42870 points

    Hi,

    jars121 said:
    Table 12-251 SerDes Supported Standards in the J721E TRM (SPRUIL1C) shows the SGMII interface as having both 1.25Gbps and 2.5Gbps bit rates. My understanding is that for SGMII to support 2.5GBASE-T, the baudrate needs to be 3.125Gbaud to deliver 2.5Gbit throughput with 8b/10b encoding. Can you please clarify whether this is correct, and if so, whether 2.5GBASE-T (at 2.5Gbit/s) is supported?

    Yes, your understanding is correct. SerDes line rate is configured as 3.125G as it is 8b/10b encoding and decoding.

    jars121 said:
    If 2.5GBASE-T is supported at the full data rate, is there a suitable quad port 2.5GBASE-T PHY that you could recommend?

    I haven't come across any of Quad 2.5G PHYs, usually QSGMII PHYs will be available at 5Gbps and using 4 SGMII Ports one as master and rest 3 are subports. The same is available in ti.com suitable for TI EVM.

    jars121 said:
    MaxLinear GPY245 which appears to be suitable, but it provides four SGMII+ interfaces, which seem to be SGMII interfaces that support 3.125Gbaud. Assuming that the answer to question 1 above is that 3.125Gbaud is supported,

    Yes, your understanding is correct.

    Best Regards,
    Sudheer

  • 0 in reply to Doredla Sudheer Kumar
    Intellectual 635 points

    Brilliant, thank you very much for clarifying.

    Thank you for providing the TI link; I've already noted the PHY used in that expansion card as a potential solution if I opt for a gigabit connection.

    It might not be possible due to cost and space constraints, but I suppose it is possible to have four independent 2.5G PHYs, each connected to a SGMII SerDes lane?

  • 0 in reply to jars121
    TI__Mastermind 42870 points

    Hi,

    jars121 said:
    but I suppose it is possible to have four independent 2.5G PHYs, each connected to a SGMII SerDes lane?

    Yes, It is possible. As pointed above "MaxLinear GPY245" has 4 SGMII+ connections each with 2.5Gbps.

    Best Regards,
    Sudheer