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SN74AVC8T245: For RGMII

Jerry Chu
Genius 4915 points
Part Number: SN74AVC8T245

Hi Expert,

I saw a lot of E2E data, there are mentioned about the SN74AVC8T245 could meet RGMII, but when the data frequency is 125MHz, the "Time" would be 8nS,

The voltage level is from 1.8V to 2.5V, the datasheet shows the MAX tPLH and tPHL both are 4nS. It seems very margin for the application.

Does I mistake anything? Or we have other good device for the application? Thanks!

  • 0
    TI__Mastermind 30815 points

    Hello Jerry,

    Please refer to Hattie's answer in this thread:

    The SN74AVC8T245 will be fine for 125MHz. If you need more clarification feel free to ask. 

  • 0 in reply to aozer
    Genius 4915 points

    Hi Aozer,

    But I got the other document, it didn't suggest 4ns propagation type buffer or level-translated device. Could you help to clarify it? Thanks!

    Page40.

  • 0 in reply to Jerry Chu
    TI__Mastermind 30815 points
    Hello Jerry,

    I just wanted to update you. I have notified an engineer who is more familiar with this and can give you more accurate feedback, they should respond soon.
  • 0 in reply to aozer
    Genius 4915 points
    Hi Aozer,
    Any update? Thanks!
  • 0 in reply to Jerry Chu
    TI__Mastermind 30815 points
    Hello Jerry,

    Sorry that he never replied, I have been speaking to my colleagues and from what I understand, the 4ns propagation delay shouldn't be an issue if you are only communicating between a host device and a single peripheral device. The timing can be an issue if you have multiple peripheral devices, and one of those devices is receiving the signal 4ns later the other peripherals.

    Another thing to consider is the channel-to-channel skew. AVC translators are guaranteed to have a maximum skew of 1 ns betwen pins on a single device but the typical skew values are usually closer to 250 ps, assuming an equal load across the pins. If these channel-to-channel skew values are within your specifications, I do not think you will run into any issues.