[sdiy] Low supply voltage monitoring..

[Jean-Pierre Desrochers]

Hi list,
I'm in the design off a low supply voltage monitor
module for my Dotcom modular supply voltages.
+15v, -15v, +5v will be monitored..
Details:
If my +15v drops <= +14.90v its corresponding monitor led
will go OFF meaning "Bad supply line"
When it comes back to >= +14.95v the monitoring led
will light back to acknowledge normal operation.
(Hysteresis of 0.05v)
The same applies for -15.0v:
led goes OFF at <= -14.90v and lights back at >= -14.95v
And for the +5v:
led goes OFF at <= +4.90v and lights back at >= +4.95v
I managed to monitor all these voltages using
a PIC16F88, REF02 5.00v reference IC and precision dual opamp
with success.
I checked some dedicated Microprocessor voltage monitors
made by Maxim Semi and others but they have
too large hysteresis voltages (typicaly 1.25.. 1.75v).
So does anybody have a good source for
precise voltage monitoring such one that
would have good specs ?

P.S. I need my supply lines not to go far
      from their normal working values..
      Specialy for my VCO's and VCF control voltages..
      Am I too 'picky' on my specs on that ?
      Would a supply voltage drop of 1.00v or more be catastrophic
      on sensitive modules ??

Happy new year to all of you guys !
JP