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ISO7221M

Aaron Spaete
Expert 4275 points
Other Parts Discussed in Thread: ISO7221M

Folks,

What happens to the output of the ISO7221M if it receives an input pulse less than the minimum input pulse width (6.67 ns) stated in the data sheet on page 3?

Regards,

Aaron

  • 0
    TI__Intellectual 970 points

    Greeting Aaron,

    The most common thread we encounter with a pulse width less than the datasheet min is that one edge of the pulse will pass through the AC-Channel while the other edge will not.  This can cause a bit at the output to be different than that at the input until an asynchronous internal DC refresh cycle occurs and corrects this difference.  If other data bits occur before the refresh, then it can appear as data is being lost.

    My applications recomendation/solution: Is to add an RC Filter at the inputs to limit your minimum pulse width presented to the device.

    Regards,

    Bryce

    TI Applications Engineer

  • 0 in reply to Bryce Sinclair
    TI__Expert 4275 points

    Bryce,

    Could we recommend the RC filter?   What parameters would you need?

    Regards,

    Aaron

  • 0 in reply to Aaron Spaete
    TI__Intellectual 970 points

    Arron,

    This will have to be custom tuned based on the customer's board and the data-rate at which they want to run.  Usually, we see system noise as the most common cause of narrow pulses, so I recommend picking an RC filter to attenuate those specific noise frequencies.

    Regards,

    Bryce