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Original question:

DP83867CS: SGMII latency

DP83867CS: SGMII latency

Jim Laser
Prodigy 55 points
Part Number: DP83867CS

I note from the datasheet for the DP83867ERGZ PHY that it claims “Extra Low Latency TX < 90 ns, RX < 290 ns” in Features. It also provides nominal RGMII to MDI latency of 88 ns and nominal MDI to RGMII latency of 288 ns (presumably the source for the numbers provided in the Features quote). However, our usage of this device is via SGMII, rather than RGMII. I don’t see anything in the datasheet that discusses latency for SGMII.

Can someone please provide details for SGMII to MDI Tx latency and MDI to SGMII Rx latency?

Thank you,
Jim

  • 0
    TI__Mastermind 26320 points
    Hi,

    Their are no standard Tools available to decode data on SGMII interface and measure the Tx and Rx path latency separately. Best way is to use Loop Back on SGMII and measure the latency of complete path ( TX+RX).

    Is latency critical for your application ? What is the budget you have ?

    Regards,
    Geet
  • 0 in reply to Geet Modi
    Prodigy 55 points

    Hello Geet,

    Latency is critical from the perspective that I am working on doing verification of some hardware requirements we have that call out specific maximum transmit and receive latencies for our usage of this device. While it may indeed be possible to look at the loopback TX+RX timing to show the hardware satisfies the requirements, I wanted to check here first.

    It appeared from the related forum item that TI was working on doing some analysis/testing that was going to be shared with the original poster off-line. Can that data be shared with me as well (off-line is fine)?

    Regards,
    Jim

  • 0 in reply to Jim Laser
    TI__Mastermind 26320 points
    Sure. Please share your email id, I will be able to provide some estimated values.

    Regards,
    Geet
  • 0 in reply to Geet Modi
    Prodigy 55 points

    Geet, thank you. A while back now, I selected +Connect to send you a friend request, so that you could email me. Is there some alternative method of contact that you were proposing?

    Jim

  • 0 in reply to Jim Laser
    TI__Mastermind 26320 points
    Hi Jim,

    Accepted your invite. Closing this thread.

    Regards,
    Geet