18 Jun
2009
18 Jun
'09
6:52 p.m.
blstuart at bellsouth.net wrote:
It was a National book, but I can believe that it could
well be incomplete. That's why I equivocated and said
it suggested a time frame. The existence of it in these
earlier systems clearly moves the lower bound.
Funny that it wouldn't even be mentioned, perhaps the chip was old enough by
that time that it got left out of a current-techniques handbook (as opposed to
a databook) in favor of newer stuff.
Could be. It's one of the thinnest of the National books
I have, and it was distributed through Radio Shack. So
it might well be a "greatest hits" compilation. It does
include the [123]09, [123]17, 120, [123]23, [123]25,
[123]26, [123]27, [123]40, 341, 342, [123]45, 78XX,
78LXX, 79XX.
BLS
I just checked what I have. My 1977 Voltage Regulator
Handbook doesn't list it at all.
My 1980 Linear Databook
includes a couple of switchers among the typical applications.
That would suggest such a data sheet would have to be
around 1978 or 79.
The earliest example I have at hand for the 723 is the manufacturer's schematic
for the Wang 520 calculator. The power supply page with two 723's on it (used
just in linear mode), is dated early 1971. Perhaps the earlier handbook was
from a manufacturer that didn't 2nd-source it.