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AM5748: MDIO specification

matusan
Guru 10235 points

Part Number: AM5748

 Hello, TI Experts,

 

Our customer sent us questions about MDIO specification of AM5748.

They reported us the unexpected behavior like below;

- They said "MDIO7(Delay time) spec in below datasheet show "10-390[ns]".  

     http://www.ti.com/lit/ds/symlink/am5748.pdf　

     5.10.6.18.2 GMAC MDIO Interface Timings

 

- But their observation result is about 500[ns] like attached pdf.

       - They use IOSET7(F6,D3).

 

And they also found related E2E-thread like blow;

This thread said "the MDIO diagram as reproduced in the datasheet is incorrect."

https://e2e.ti.com/support/processors/f/791/t/791070

 

Question:

   - Could you tell us the reason or comment of this difference about MDIO spec?

   - Are there any problem or mistake in the below datasheet ?

     http://www.ti.com/lit/ds/symlink/am5748.pdf　

     5.10.6.18.2 GMAC MDIO Interface Timings

 

Best regards,

mdio1.pdf

  • 0
    TI__Mastermind 27890 points

    Hello,

    As per the referenced thread, the MDIO timing diagram and values in the existing DS are incorrect. This will be rectified in upcoming revisions of the document.

    Please use the -150/150 values as outlined.

  • 0 in reply to -DK-
    Guru 10235 points

    Hi,

    Thank you very much for your kindness.

    I really appreciate your help.

    We are waiting for next datasheet update.

     

    We understand that your answer for MDIO7 spec is same of the below E2E-thread.

    https://e2e.ti.com/support/processors/f/791/t/791070

      - Td (MDC-MDIO) | "Delay Time: MDC Low to MDIO Valid" | MIN: -150ns MAX:150ns

      - The timed edge has changed from rising edge to falling edge.

     

    And our customer sent us additional questions for MDIO4 and MDIO5 spec in the below datasheet.

         http://www.ti.com/lit/ds/symlink/am5748.pdf 　

         5.10.6.18.2 GMAC MDIO Interface Timings

     

    Their understanding is like below for MDIO4 and MDIO5 spec.

    - The timed edge should be also changed from rising edge to falling edge for MDIO4 and MDIO5 spec.

    - The below value in the datasheet will not be not changed in future released datasheet.

           - MDIO4 : (min) 90 ns

           - MDIO5 : (min) 0 ns

     

    Question:

      Is this understanding correct?

    If there is difference of future update released datasheet for MDIO4 and MDIO5 spec, please tell us proper specification.

     

    Best regards,

  • 0 in reply to matusan
    TI__Mastermind 27890 points

    Hello,

    Only the output timing will change. The input timing values and timed edge will not change.

    In other words: MDIO 4/5 are unaffected.

  • 0 in reply to -DK-
    Guru 10235 points

    Hi,

    Thank you very much for your kindness.

    I really appreciate your help.

    I will send the answer to the customer.

    Best regards,