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ISO7021: latency IN/OUT on impulsion

yves gagniere
Intellectual 1565 points
Part Number: ISO7021

Hi ,

need to understand device behavior when ISO get a very low frequency signal on the input that need to be acquired promptly. If the input is stable for more than 100ms and an impulsion is applied on the input does this information is instantly provided to the output or the output is delayed due to refresh rate because of the BF mode is activated?

DR max being 4Mbps while FR max being 10Kps according to the DS.

Thanks 

  • 0
    TI__Mastermind 49445 points

    Hi Yves,

    The propagation delay between input and output is going to be as stated in the datasheet, 140ns typical. This is also true when an impulse is applied, irrespective of what the refresh rate is. Every time there is a transition at the input, it will propagate to the output according to datasheet propagation delay spec.

    The refresh rate only comes into picture upon device power or any other unusual fault conditions, where for some reason the input and output are not matching and the input data is not changing. To fix this mismatch and make output match the input, it could take about 100µs. Otherwise, even when there is a mismatch and if input data changes then the output will immediately respond follow input signal.

    For most operating conditions, you could just ignore the refresh rate and refer to other timing specifications. Only for special test conditions where the device is forced into input and output mismatch mode like upon power-up or after a CMTI event of >100kV/µs, refresh rate decides how quickly that mismatch is fixed. Thanks.


    Regards,
    Koteshwar Rao