This is the problem I too had for a long time with
Schottkys. You'd see them in circuits, you'd see them
referred to in messages, you'd see descriptionss -- as in
AoE -- of when you'd want to use one, but despite however
common they were, for some reason no one ever explains
*what* they are. Like, descriptions of how a FET works are
a dime a dozen, but it seems as if it is assumed that by
the time you care about Schottkys you already know what
they are.

As a total coincidence, just last night I went looking
for a real description of them (AoE doesn't help here,
as far as I could tell). After two hours (!) of digging
through vendor websites and general-purpose search engines,
(endless product bulletins, EE course descriptions,
how-they-are-used notes, etc.), I finally came up with
this reference:

http://www.microsemi.com/micnotes/400ser/401.htm

Which was more like what I was looking for. The document is
also available as a pdf at:

http://www.microsemi.com/micnotes/401.pdf

Undoubtedly I just wasn't doing a good job of
Web searching, but nevertheless I wrote to
Microsemi to say thanks for having that document
up... :-)

--Bob

On Tue, May 11, 1999 at 10:32:49AM -0700, Mark Willis wrote:
> Roland Andrag wrote:
> >
> > >Sorry about my lag of analogic electronics, but what is a Schottky Diode ?
> >
> > Also called a 'hot-carrier' diode. Basically it has a very low forward drop
> > voltage - say around .25 V instead of the normal silicon 0.6 to 0.7 V.  A
> > very good book is The art of electronics, by Horowitz and Hill, if you plan
> > to learn anything but basic electronics, especially analogue. It contains
> > just as much digital electronics knowledge, but no PICs. Still a must have.
> >
> > Cheers
> > Roland
>
>   They're a little more expensive than 1N4148's et al, they're great
> where you want to drive a circuit off a Parallel Port, or anywhere else
> that those diode drops add up too fast and you need them not to.
> They're also pretty fast diodes, so protection networks are great when
> done with Schottky's.
>
>   The forward voltage drop does come up to more like 0.4V at higher
> currents, still about 1/2-1/3 the drop can mean your circuit works
> without a "Wall Wart".
>
>   Mark

--
============================================================
Bob Drzyzgula                             It's not a problem
bob@drzyzgula.org                until something bad happens
============================================================