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555 schmitt trigger speed

BlinkingLeds

Feb 23, 2013
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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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Harald Kapp

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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.
 

BlinkingLeds

Feb 23, 2013
180
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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.

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)
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Have you considered a mosfet driver? That would appear to be exactly what you want.
 

BlinkingLeds

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