> >From: Dave Dilatush <davedilatush@COMCAST.NET>
> ....
> >You have it right: the "droopout voltage" spec gives you the
> >minimum required input-output differential needed for the
> >regulator to operate.
>
> Or else, what happens? I've always wondered. F'r instance, if it's a
5V
> regulator
> and the input is 5V, what's at the output?

You know, I could swear I've seen a regulator do the following bad
thing, but I can't recall at all what device it was.  I wish I could, so
I could avoid it forever:

as soon as the input voltage went below the sum of the output voltage
and the dropout voltage (that is, the normal minimum you need to get the
right voltage out), the device acted like a simple diode _in_conduction_
(with the 0.6v drop across it).  So the 5V regulator that needed 7.5V
and got 7.2V was giving 6.6V to my circuit.  Riiight.

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