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TXS0108E: Data rate conflict

Ryan.Bishop
Expert 3900 points
Part Number: TXS0108E
Other Parts Discussed in Thread: TXS0206A, SN74AVC4T234, SN74AUP1T17, SN74AVC4T774

Hello,

The parametric table and front page of the datasheet states: Maximum Data Rates – 110 Mbps (Push Pull)

However, Sections 6.6 through 6.15 state that the maximum data rate TI guarantees is 20-60Mbps depending on the supply voltages.

There seems to be a huge gap between what performance is advertised and what performance is guaranteed. I may be misunderstanding something, so please correct me if so.

Would we recommend a customer use this part for speeds between 60-110Mbps?

Thank you,
Ryan B.

  • 0
    TI__Guru 62240 points
    Ryan,

    The 60Mbps is the min data rate and typically it can go higher up to max 110Mbps.
    I want to know what is the application and system requirements. Would the data rate be a key requirement, and if auto bidirectional translators are needed?
  • 0 in reply to ShreyasRao
    TI__Expert 3900 points
    Hi Shreyas,

    Thanks for your quick answer.

    To follow up, this is for a 100Mbps SDIO connection. To me the TXS0108E does not seem to be the best part since not all pieces are guaranteed to hit 100Mbps (given that proper PCB layout is done).

    Do we have an auto-directional level shifter that is designed for 100Mbps data?

    My other thought is to see if the customer can use the SPI protocol that is compatible with SD interfaces. This does not have bi-directional data. Perhaps we will have a better option in this case?

    Thank you,
    Ryan B.
  • 0 in reply to Ryan.Bishop
    TI__Guru 62240 points
    Hi Ryan,

    There is TXS0206A device which has a max clock rate of 60Mhz ( 120Mbps), but the data rate on the IO pins are up to 60Mbps.
    This is an application specific device supporting the SD card interface.
    The clock pins are buffered but the IO pins are auto bidirectional and hence cannot achieve high data rates.
  • 0 in reply to ShreyasRao
    TI__Expert 3900 points

    Hi Shreyas,

    I am trying to explore using the SPI protocol to communicate with the microSD card. This would require 3 unidirectional data lines going to the card (DI, SCLK, CS) and 1 unidirectional data line going back to the host (DO).

    My only concern here is the delay introduced to the clock. The SD card will be operating from a clock that has been slightly delayed by the propagation delay of the level translator. When it attempts to send data back to the host, will the host interpret the data correctly since it's own clock is slightly "ahead" of the SD card's clock?

    Thank you,
    Ryan B.

  • 0 in reply to Ryan.Bishop
    TI__Expert 3900 points
    I was thinking SN74AVC4T234 for data to the card

    and

    SN74AUP1T17 for data from the card
  • 0 in reply to Ryan.Bishop
    TI__Guru 62240 points
    Hi Ryan,

    For the SPI interface, I would recommend the SN74AVC4T774. Each of the IO port has DIR control which can be configured for SPI operation.
    This device supports greater than 100Mbps data rate.