Hi,
We have a signal that is alternates between being high for 7s and low for 2s. We want to limit any single high pulse to 20s.
Initially I was going to use a SN74LVC1G123 monostable multivibrator, with Cext=10uF and Rext=2M, as the datasheet does not mention maximum values. Alas TI support do not recommend having Rext greater than about 660K or Cext above 10uF - limiting the period time to 6.6s.
I am looking for alternatives. I will try a TLC555-Q1 set up as a monostable, invert our trigger signal (using a SN74LVC1GU04DBVT) and connect it to both the 555's trigger input and the reset signals. Will this work? Is there a better more modern single IC solution?
The circuit is powered from 3.0V and only needs to drive the gate of a N type MOSFET. The trigger signal comes from a PIC I/O pin and needs to be backwards compatible with older software (hence the inverter for the 555).
Thank you,
Ian