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(ADuM14x)What will happen if input is HiZ.

Hi !

I have some questions about ADuM14x.

At our customers system sometime the device which is connected to ADuM14x input outputs HiZ.

So my question are these.

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Q1)

I already know that ADuM14x don't have internal resistor.

(ADuM14x)Does ADuM14x has internal Pull-up or Pull-down resistor? 

What will happen if all supply are powered and input is HiZ.

I think output will be Indeterminate.

Is this correct?

Q2)

If our customer input HiZ to ADuM14x , would it cause some problem to the device?

For example, some kind of digital device will broke up when input is HiZ.

Q3)

At datasheet , this is written.

What do you mean

"The ADuM140D/ADuM140E/ADuM141D/ADuM141E/
ADuM142D/ADuM142E digital isolators require no external
interface circuitry for the logic interfaces."?

If there is HiZ input mode at system and if the customer want to control the output , I think they should insert Pull-up or down resistor to input pin.

Can our customer do this?

But at the datasheet "digital isolators require no external interface circuitry for the logic interfaces" so I want to ask can our customer insert resistor to the input signal line.

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Also the competitor chip has internal resistor so it won't be a problem if input is HiZ.

So if our customer have Pull-down/up resistor , it would become disadvantage.

Best regards.

Kawa

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  • Hi Kawa,

    Q1)What will happen if all supply are powered and input is HiZ.

          I agree that the output will be indeterminate.

    Q2)If our customer input HiZ to ADuM14x , would it cause some problem to the device?

          I think it should not be a problem because ADuM14x has high input impedance.

    Q3) can our customer insert resistor to the input signal line.

          If the customer wants to control the input state, and there exists HiZ, I also agree that they should add pull-up or pull-down resistors to the input of our digital isolators.

    Regards,

    Neil

Reply
  • Hi Kawa,

    Q1)What will happen if all supply are powered and input is HiZ.

          I agree that the output will be indeterminate.

    Q2)If our customer input HiZ to ADuM14x , would it cause some problem to the device?

          I think it should not be a problem because ADuM14x has high input impedance.

    Q3) can our customer insert resistor to the input signal line.

          If the customer wants to control the input state, and there exists HiZ, I also agree that they should add pull-up or pull-down resistors to the input of our digital isolators.

    Regards,

    Neil

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