ADuM1401 input

We’ve been doing some tests on above, and get considerable oscillation on output when i/p risetime is 100us or so. Please see attached screenshot: yellow trace is i/p signal, 4.9v p-p, risetime of 100us (ignore Y axis scale for signal – x10 probe attached). Blue trace is o/p signal – as you can see, any amount of noise on i/p is giving rise to multiple o/p transients.

Is there any form of hysteresis on the input? The datasheet implies it’s Schmitt but it doesn’t act like it. Is there a pin for pin compatible device which does have Schmitt inputs?

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    •  Analog Employees 
    on Dec 8, 2015 6:54 PM

    Hi,

    ADuM1401 is standard CMOS input logic, it have hysteresis at the input. If the input signal rising time or falling time is not so slow, you will find the different judge voltage level between rising and falling. But in your case, the time last so long during the undefined input voltage level. This is like you put one middle voltage at the input. So the output is indeterminacy.

    Thanks.

    Jian

Reply
  • 0
    •  Analog Employees 
    on Dec 8, 2015 6:54 PM

    Hi,

    ADuM1401 is standard CMOS input logic, it have hysteresis at the input. If the input signal rising time or falling time is not so slow, you will find the different judge voltage level between rising and falling. But in your case, the time last so long during the undefined input voltage level. This is like you put one middle voltage at the input. So the output is indeterminacy.

    Thanks.

    Jian

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