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ISO7340C: input threshold

Hans
Genius 12705 points
Part Number: ISO7340C
Other Parts Discussed in Thread: SN74AHCT1G14

Hello Team,

please provide "positive-going input threshold" and "negative-going input threshold voltages" as the blockdiagram in the data sheet show a Schmitt-Trigger. Schmitt-Trigger data sheets (e.g. SN74AHCT1G14) typically have this specified.

I also noticed a specified threshold voltage of 480mV (at 5V supply) but page 3 tells me: "The ISO734x-Q1 device has TTL input thresholds and operates from 3-V to 5.5-V supply levels."

To my knowledge TTL thresholds at 5V are LOW below <=0.8V and HIGH >= 2.0V. This does not match with the 480mV (page 9).

Please let me know what is wrong.

Thanks and Best Regards,

Hans

  • 0
    TI__Intellectual 2900 points
    Hi Hans,

    Please find my explanation below.
    The High level and Low level threshold voltages are mentioned in the "Recommended Operating Conditions" (Section 7.3)
    As you have mentioned, HIGH >= 2.0V and LOW<=0.8V is guaranteed by the device. But the actual switch point from High to Low and Low to High will be in between 0.8V and 2.0V. The positive and negative going switching points will be between 0.8V and 2.0V so that the recommended operating condition is guaranteed.

    The difference between the positive going threshold and negative going threshold will be 480mV. This is what the parameter VI(HYS) = 480 mV mentions.

    I hope this answers your query.

    Regards,
    Anand Reghunathan