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SN74AHC1G08: Hysteresis value

May
Genius 9880 points
Part Number: SN74AHC1G08
Other Parts Discussed in Thread: SN74LVC2G17

Hi Team,

In the datasheet it mentioned Schmitt-Trigger, customer is requesting if we could provide a table of its hysteresis values just like in the datasheet of  SN74LVC2G17. 

Thanks.

Regards,
May

  • 0
    Guru 265760 points

    The guaranteed hysteresis is zero. "Schmitt-trigger action" is not the same as a real Schmitt-trigger input.

    The AHC application report says:

    Input hysteresis of typically 150 mV is included in AHC devices, which ensures the devices are free from oscillations by increasing the noise margin around the threshold voltage during low-input transitions.

    The AHC Designer's Guide says:

    Hysteresis in the input circuit is intended only to process reliably signals that have a slew rate of <10 ns/V. With a signal swing of 5 V, this corresponds to rise and fall times of about 50 ns. If signals with considerably longer rise and fall times are processed, the specially developed Schmitt triggers, such as the SN74AHC(T)14, should be used. These components have a considerably larger hysteresis of about 800 mV at VCC = 5 V and, therefore, allow processing of very slow edges without any problems.