Negative voltage one shot - 2 usec

Discussion in 'General Electronics Chat' started by atferrari, Mar 28, 2015.

  1. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
    I need to implement a one-shot stage to generate a negative voltage pulse (0 to -3V) lasting around 2 usec, triggered by a TTL pin of a micro. Dual PSU (+/- 5V) available.

    Been considering an LM311 connected between 0 and -5V. I got just one! of those comparators for the week end and I fear to destroy it in any uncontrolled test. Additionally I cannot see how to trigger it with a positive voltage and even more as a one shot.

    Reading the datsheet got me even more confused.

    Any ideas about this or any better/simpler?
  2. JWHassler


    Sep 25, 2013
    IF you let the microprocessor handle the one-shot timing (like it's supposed to)
    AND you're not real finicky about the output levels
    AND not much drive is needed, this might do it
  3. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    What is the pulse used for? What kind of current must it supply in both the hi and low states? Does it need to come from a low impedance source such as the output of a digital logic part or an LM311? If a medium impedance source work, the above circuit is a nice approach.
  4. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
    I think it could be OK. It is about 120 uA when pulling down to about -3V.