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TXS0102 pull up resistor problem

Soccer Wang
Prodigy 500 points
Other Parts Discussed in Thread: TXS0102, SN74AVC2T245, SN74AVC2T45, SN74AVCH2T45, SN74AVC2T244, TXB0101

                I am account analog FAE of Suzhou IVO who’s the China leading panel maker customer. Now, we have DIN TXS0102 in their notebook panel for open drain level translator.

               As we known, the internal pull up resistor is 10k, when the input signal is floating, the voltage of point 1 is 3.3V*(1k/(1k+10k))=0.3V which is larger than VIL (max=0.15V), so the output status is unknown at this time. While, my customer requires the output voltage is low during the input is floating.

               I also checked the other type level translator (SN74AVC2T244, SN74AVC2T245, SN74AVC2T45, SN74AVCH2T45, etc.), but the datasheet doesn’t show the specific data regarding the pull up or pull down resistor.

               Could you give any suggestions regarding this requirement (the output is low when input is floating.)?

              

 Thank you very much.

  • 0
    Guru 74080 points

    You could add an external transistor, but this also inverts your logic, of course.

    What about the TXB0101?

  • 0
    TI__Expert 6335 points

    Soccer,

    I apologize for the late response on this. My feedback is below:

    Soccer Wang said:

    As we known, the internal pull up resistor is 10k, when the input signal is floating, the voltage of point 1 is 3.3V*(1k/(1k+10k))=0.3V which is larger than VIL (max=0.15V), so the output status is unknown at this time. While, my customer requires the output voltage is low during the input is floating.

    The VOL and VIL relationship is documented in the TXS0102 datasheet.

    Soccer Wang said:

    I also checked the other type level translator (SN74AVC2T244, SN74AVC2T245, SN74AVC2T45, SN74AVCH2T45, etc.), but the datasheet doesn’t show the specific data regarding the pull up or pull down resistor.

    Could you give any suggestions regarding this requirement (the output is low when input is floating.)?

    1k pulldown resistor would be ok. I would avoid the AVCH product since it has bus-hold and we generally recommend not to use pulldown resistors on those parts.

    Best Regards,

    Nirav

  • 0 in reply to Dennis Eichmann
    TI__Prodigy 500 points

    Thank you for your suggestion, TXB0101 is only for push pull, not for open drain.

  • 0 in reply to Nirav Patel
    TI__Prodigy 500 points
    Thank you for support.