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DS26C31MQML: Non-operating (no power supply), is the output pin of the part high impedance?

daejin kang
Intellectual 320 points
Part Number: DS26C31MQML

Hello

I'm daejin kang, and work in Satrec Initiative in south korea.

when, this part is non-operating (no power supply), is the output pin of the part high impedance?

I will design for redundancy structure. therefor, the output pin of two parts is connected together.

My design is that the power of two parts is used individually for operating. Therefore, when power is supplied to one part, it isn't supplied to the other part. at this time, the output pin of the non-operating part must hold high impedance. Is it possible?

  • 0
    TI__Guru 62930 points
    Daejin,
    This is specified in the datasheet.
    The parameter is Ioff. It has a limit of +/-100uA when Vcc = 0.

    If this answers your question, please click "Verify it as the answer"
    Regards,
    Wade
  • 0 in reply to Wade Vonbergen
    Intellectual 320 points

    hi

    thank you for answer

    in addition, I have a question.

    Is it a problem?, if the output of part is entered to output pin of the other part. when, the other part is non operating (not supplied the power)

    (e.g. part failure due to stress of other part, uncertain output signal and so on) 

    thank you

  • 0 in reply to daejin kang
    TI__Guru 62930 points

    Daejin,

    I am not certain I understand your question.

    Can you elaborate each device that you are considering, and what pins?   Are you considering case where the line driver will be driving onto a bus shorted to GND or VCC?

    If so, this is also specified in the datasheet for parameter Isc.   The device can survive this, as long as it is only a single output pair.  Multiple outputs shorted is not warranted.  

    Regards,

    Wade

  • 0 in reply to Wade Vonbergen
    Intellectual 320 points

    hello, Wade

    I'm sorry. I will explain in more detail.

    My design concepts are:

    I use two ds26c31. (Part 1, Part2)

    the Part 1 is supplied the power, and the Part 2 is not supplied the power.

    The output pins of the two ds26c31 are connected together.

    When operating in this configuration,

    Is the non-supplied Part 2 dangerous?

    Is there a problem with the 422 interface?

    is this possible?

    thank you

  • 0 in reply to daejin kang
    TI__Guru 62930 points
    Daejin,
    Part 2 will not be an issue when it is unpowered. This is the Ioff parameter. It will only leak at the most +/-100uA when Vcc = 0. It may be important to make sure that VCC=0, and does not get pulled up by ESD diodes and partially bias part 2.

    Inputs and enables on part #2 must not violate the absolute max table. Ie, they need to not be driven.

    Regards,
    Wade