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66AK2H14 MDIO Timing Requirements

Yasunori Saito
Intellectual 460 points

Other Parts Discussed in Thread: 66AK2H14

Hi,

I have some questions about "MDIO Timing Requirements" in 66AK2H14.

I refer to "Table 10-49 MDIO Timing Requirements" in datasheet(sprs866e.pdf, p325).
In here, th(MDCLKH-MDIO) is defined as 10 ns.



In the MDIO specification(IEEE802.3 Std), "MDIO clock to output delay" is defined as Min = 0 ns, Max = 300 ns.




・th(MDCLKH-MDIO) in 66AK2H14 is 10 ns,
・the MDIO clock to output delay is a minimum of 0 ns.

1.
In most PHY devices, the output delay time is a minimum of 0 ns.
Therefore, I think that it cannot meet the "MDIO Timing requirements" in 66AK2H14.

To meet the "MDIO timing requirements" in 66AK2H14,
I think that the data signal(MDIO) must be delayed more than 10ns than the clock signal(MDC).

Is this correct?

2.
Is the data sheet not mistake ?


Best Regards,
Yasunori

  • 0
    TI__Guru* 81335 points

    Welcome to the TI E2E forum. I hope you will find many good answers here and in the TI.com documents and in the TI Wiki Pages (for processor issues). Be sure to search those for helpful information and to browse for the questions others may have asked on similar topics (e2e.ti.com). Please read all the links below my signature.

    We will get back to you on the above query shortly. Thank you for your patience.

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  • 0
    TI__Mastermind 43660 points
    Yasunori,

    The setup time and hold time requirments are same in both 66AK2H14 data manual and the MDIO specification document. I am not sure about the MDIO clock to output delay which is not mentioned in the device data manual. I am not able to find the MDIO specification document to explore this. Please refer Figure 22-19 to see what this MDIO clock to output delay depicts.

    Regards,
    Senthil
  • 0
    TI__Mastermind 42545 points

    Hi Yasunori,

    In reviewing the internal information on the timing of the MDIO I found that the information in the K2H data manual is incorrect. The information in the data manual was culled from the Ethernet spec and wasn't changed to reflect the station agent status of the K2H. I will file a lit bug against the specification and have it fixed in the next revision. The 10ns hold time requirement will be removed. Since the hold time is 0ns, care should be taken in the routing of the MDIO interface to ensure that the clock signal is not longer then the data signal. That would result in the clock arriving after the data is allowed to change.

    Regards,

    Bill

  • 0 in reply to Bill Taboada
    Intellectual 460 points
    Hi Senthil,

    Thank you for your information.


    Hi Bill.

    Thank you for your help.

    I understood that as follows.
    ・The 10ns hold time requirement in the K2H data manual is incorrect, it will be fixed in the next revision (hold time is 0ns).
    ・The additional delay is not necessary if the clock signal is not longer than the data signal in the routing of the MDIO interface.


    Best Regards,
    Yasunori