• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 19 subscribers
  • Views 357 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

RMII & MDIO Level Shift IC

Charge Kuo1
Prodigy 70 points
Other Parts Discussed in Thread: LSF0102

Hi
When I looked for a solution for RMII & MDIO level shift, I got confused about SN74AXCH8T245RHLR and TXB0102DCUTG4.
The datasheet of TXB0102DCUTG4 shows it cannot use strong pull high or down resistor, because of the drive resistor is 4K Ohm.
Is there the same "note" in SN74AXCH8T245RHLR?

Because my RMII signals have the strap function and the recommended pull up/down resistors are 4.7K~10K, I don't know if I can use SN74AXCH8T245RHLR or not?

The MDIO signal is bi-directional, and the minimum rate is 20MHz. The switch chip also shows needs pull up resistor and 10K Ohm.

Could you help to find the component?
Thanks

  • 0
    TI__Mastermind 45725 points

    Hey Charge,

    I recommend the SN74AXC8T245RHLR device instead as it will have no issues with a 4.7k~10k pullup/pulldown resistor on the I/O. Its identical to the device you mentioned but it doesn't have the Bus-hold functionality (its not recommended to use pullups/pulldowns with Bus hold devices). For MDIO, my best recommendation would be the LSF0102 since it supports bi-directional open drain interfaces. Translating 20 MHz may be difficult, but it will depend on the size of the pull-ups used (these will have to be much smaller than 10 k) and the drive strength of the interfacing devices. Here are training videos that go into great detail on the LSF family and will enable you to best implement the device in your system. 

  • 0 in reply to Dylan Hubbard
    Prodigy 70 points

    Hi 

    I got it!

    Thanks