TURN ON LED AT CERTAIN INPUT VOLTAGE RANGE

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Dinny24

Joined Jan 7, 2020
2
Hi Guys
I am working on a small project where I need to Drive LED ON when the input voltage is between 23V and 25V. Turn OFF LED when the input voltage is <23V and >25V.
Do you guys have any suggestions? Apologies if the question has already raised elsewhere.
TIA
 

crutschow

Joined Mar 14, 2008
24,076
Yes, a window comparator should work for you.
You can use a LM339 or LM393 comparator (2 comparators in the package used), with a TL431 voltage reference for the levels.
Below is the LTspice simulation of an example circuit:
The LED D1 (blue trace) is on between 23V and 25V input (yellow trace).
How close to those values does the actual trip point need to be?

1578424532028.png
 
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