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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  • 0
    •  Analog Employees 
    on Dec 9, 2015 7:46 AM

    Hi,

    I am sorry I think I made misunderstanding for this issue at last reply. Please ignore it.

    Yes, the issue is because of the nosie of your input signal. What's the amplitude of the input signal noise? about 80mV?

    The input hysteresis of ADuM1401 is not so large. I tested one chip in my lab is about 70mV.

    Right now, we don't have large hysteresis parts. How large of the hysteresis do you think is enough?

    Thanks.

    Jian

Reply
  • 0
    •  Analog Employees 
    on Dec 9, 2015 7:46 AM

    Hi,

    I am sorry I think I made misunderstanding for this issue at last reply. Please ignore it.

    Yes, the issue is because of the nosie of your input signal. What's the amplitude of the input signal noise? about 80mV?

    The input hysteresis of ADuM1401 is not so large. I tested one chip in my lab is about 70mV.

    Right now, we don't have large hysteresis parts. How large of the hysteresis do you think is enough?

    Thanks.

    Jian

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