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Original question:

[FAQ] Why are the TXS01xx VIH/VIL specifications so stringent?

TXS0102-Q1: follow up question on FAQ why TSX0xxx VIL/IH so stringent

Dongbao Zhou
Expert 4130 points
Part Number: TXS0102-Q1

hello,

One follow up questions on why TXS010x VIL/VIH specification so stringent, i can understand the logic that the downstream device input requirement are taken into consideration. If we don't consider the Vol/voh dependency on Vil/Vih, what are the real VIL/VIH spec?

Regards,

Dongbao

  • 0
    Guru 298390 points

    For all input voltages below VCCA, the TXS works as an analog switch. For input voltages above VCCA, the switch is open, and the output voltage is determined by the pull-up resistor. It does not make sense to specify VIL/VIH values for this behaviour.

  • 0 in reply to Clemens Ladisch
    TI__Expert 4130 points

    hi Clemens,

    Thanks for the feedback.

    Now I can understand why Vil doesn't make sense due to the N-FET on until input voltage higher enough to turn it off, but why VIH spec doesn't make sense?

  • +1 in reply to Dongbao Zhou
    Guru 298390 points

    Sorry, my statement might have been too strong. While there is no logic low state, it is possible to define the switch-open state as high.(And when you want to know what input voltage you need to make the output high, this is certainly the correct answer.)

  • 0 in reply to Dongbao Zhou
    TI__Mastermind 38435 points

    Hi Dongbao,

    In addition to Clemens' feedback, note that with the direct input to output connection architecture of the device; the provided specification in the datasheet is to help guarantee specified VOL and VOH levels.

    Hence, if the VOL/VOH observed is acceptable; then there should be no concerns, as they are dependent on the current of the drivers per the application's IOL/IOH and ROH i.e VOL = VIL + (IOL*Ron) and VOH = Vcc - (IOH*ROH). Please see the referenced Factors Affecting VOL for the TXS and LSF Auto-Bidirectional Translational Devices, to help further clarify, thanks

     

    Best Regards,

    Michael.