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555 schmitt trigger speed

Discussion in 'General Electronics Discussion' started by BlinkingLeds, Jul 1, 2013.

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  1. BlinkingLeds


    Feb 23, 2013
    Until now i used a p-ch / n-ch to invert a signal but i'm thinking of assigning a 555 as a schmitt trigger for this task. My only concern is speed / response time. Which of these two options is "faster"

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    Last edited: Jul 1, 2013
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    I don't think there is a simple answer.

    The 2 transistor circuit should be faster than the 555 approach (the 555 has a typical rise time and fall time off 100ns).
    However, details depend on the load and your choice of transistors.

    (ab)using a 555 for a simple inverter is overkill in my view.
  3. BlinkingLeds


    Feb 23, 2013
    it will drive a power mosfet (irf740)
    If the 555 isn't more than 2 times slower then i prefer it as it is a bit smaller in it's smd package than the two smd fets (ao3401 and 2N7002 sot-23)

    Another reason for this is that i don't have many of those tiny transistors left so i need an alternative (i don't want to wait a month to get more, to make my next pcb)
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Have you considered a mosfet driver? That would appear to be exactly what you want.
  5. BlinkingLeds


    Feb 23, 2013
    Yes but i don't have any smd drivers around. So only two available options (for now) 555 or fets?
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