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TXB0102YZPR for SDIO CLK and CMD Signals

Trent Oshiro
Intellectual 505 points
Other Parts Discussed in Thread: WL1831, TXS0108E, TXS0102, TXS0206, TXB0102

I'm currently using a TXB0102YZPR to translate SDIO_CLK and SDIO_CMD signals from 3.3V to 1.8V for the WL1831.  The SDIO data signals are directly connected to the WL1831 from MPU.  We have reason to believe this setup might be causing problems for us.  This app note (page 6, $4.1) suggests to use a different shifter TXS0108E with 10k pullups on both sides for the SDIO signals.  My questions are:

  1. Can we get away with sticking to the TXB0102YZPR instead of the TXS0108E that is suggested in the WL1831 app notes?
    1. If we can, do we need to add pullups?  My thoughts are no because the TXB0102YZPR operates with push-pull, not open-drain.
    2. If we can't, do we need to switch to the TXS0108E?  Or do we need to get rid of the shifter altogether?  Is the problem stemming from the fact that we are trying to translate just the clk and cmd lines as opposed to all or none of the SDIO signals (i.e. CLK, CMD, DATA0-4).

  • 0
    TI__Intellectual 2530 points

    Hi

    We recommend the TXS0102 or the TXS0206.

     

    Thanks

  • 0 in reply to Jennifer Joseph
    Intellectual 505 points

    Hey Jennifer,

    Just to clarify, we are only using this translator for SDIO_CLK and SDIO_CMD signals, not I2C or 1-wire.  From the TXB0102 datasheet, it states that "For the same reason, the TXB0102 should not be used in applications such as I2C or 1-Wire where an opendrain driver is connected on the bidirectional data I/O. For these applications, use a device from the TI TXS01xx series of level translators."  (Page 14). From my understanding, we would only need to use the TXS01xx if we were using open drain signals, correct?  Also, the TXS0206 seems like it would only be unnecessary since we only need to translate the CLK and CMD signals, correct?

    Thanks,

    Trent

  • 0 in reply to Trent Oshiro
    TI__Intellectual 2530 points

    Hi Trent

    Hope this is not too late. Yes, you can use the TXB0102 to interface with an SD/SDIO card.

    To prevent floating bus lines, card standards recommend adding pull-up resistors on the data and command lines.When using an auto direction sensing translator, the value of these pull-up resistors must be kept high enough to ensure that they do not contend with the weak outputs of the translator. For card interface applications using auto direction- sensing translators, the highest allowable pull-up resistor is 100k.

    I have a schematic for an 8-bit TXB part, which you can refer to below. Hope this helps.

     

    Thanks