> If you put a scope on the circuit you may see that this chip is in
> oscillation. Did you use bypass capacitors? See if it is oscillating. That
> would cause lager current draw.
>
>
> On Thu, Aug 29, 2019 at 9:14 PM Jason White <
>
RemoveMEwhitewaterssoftwareinfo
TakeThisOuTgmail.com> wrote:
>
> > Russell that is pretty clever, I am half tempted to give it a try on one
> of
> > my existing prototype boards just to see if it works. The next revision
> > will probably get Schmitt trigger ICs since this is (will be) a safety
> > sensitive application.
> >
> >
> > On Thursday, August 29, 2019, RussellMc <
apptechnzEraseME
.....gmail.com> wrote:
> >
> > > On Fri, 30 Aug 2019 at 09:05, Jason White <
> > >
EraseMEwhitewaterssoftwareinfo
gmail.com>
> > > wrote:
> > >
> > > > My application is space and power constrained. Is there a logic gate
> > that
> > >
> > > does not exhibit this behavior? (100uA in the undefined would be much
> > more
> > > acceptable than 45mA) Maybe a schmitt trigger would be designed to
> > > >
> > > >
> > > > A Schmitt triggered gate is the obvious solution, as you and others
> > have
> > > noted.
> > > Below I describe an extremely 'naughty' concept which may be able to be
> > > made to work deep-ending on overall situation.
> > > This arrangement
> > >
> > > - may not work at all
> > > - may be an utter disaster
> > > - may be able to be made to work extremely well
> > >
> > > Odds are the naughtiness factor exceeds the levels acceptable in a real
> > > world design :-).
> > >
> > > "" Solution """: Add a 'suitably sized' resistor in the IC's Vdd line..
> > >
> > > Greatly increased current drain will lower the IC's Vdd thus increasing
> > the
> > > relative voltage of the inputs relative to the IC.
> > > Reduction of current drain will restore the voltages so there is a
> > > potential for oscillation depending on time constants.
> > >
> > > (This "works", if at all, on rising input waveforms.
> > > A resistor in the Vss line will achieve a similar result with falling
> > > inputs.
> > > Both at once (probably) don't work for equal sized resistors.
> Assymetric
> > > sizing may work in both directions in some cases but, by then magic is
> > > probably safer).
> > >
> > > I have never tried this with an IC.
> > > But I have successfully added hysteresis in a transistor based circuit
> by
> > > adding a small resistor in a current path and using the small pedestal
> to
> > > raise a switching voltage level elsewhere. Not a formal Schmitt per se.
> > In
> > > that case the solution was 'almost elegant' rather than 'naughty' and
> > > produced superb results with astonishingly small levels of hysteresis
> for
> > > the results achieved. (ie calculation suggested that the level that
> > worked
> > > was far smaller than would be expected to be effective.
> > >
> > >
> > > Russell
> > > --
> > >
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> > >
> >
> >
> > --
> > Jason White
> > --
> >
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