Alt-BEAM Archive
Message #02146
To: beam@corp.sgi.com
From: Steven Bolt sbolt@xs4all.nl
Date: Fri, 9 Apr 1999 08:26:11 +0200 (CEST)
Subject: [alt-beam] Re: Better design was Better 74HC design
On Thu, 8 Apr 1999, Wilf Rigter wrote:
> Issues like "Why AC and not ALS" or "Why 74C and not 74HC" would be fun but
> rather than "championing" a logic family, I prefer to concentrate on solving
> problems with novel design solutions including your own excellent analog
> sampling method and so many other of your contributions.
Hmmm... I see that I should have worded it differently, or maybe
should have used even less words.
People are still using 74LS, 74HCT and any other 74XXX where 74HC
is specified. "Can I use ..." and "Why not use..." are the
questions I answer most often. TI points out a difference between
families which are often thought to be equivalent even by
`advanced' BEAMers, and does it in an easy to understand way. It
seemed worth the minor effort of posting.
Of course there are valid reasons for using 74AC, or a sensible mix
of two or more families. So when someone thinks he/she needs the
higher sink/source capability of 74AC, he/she may consider "Yes,
but in this part of my circuit, that means (solar) power going to
waste - no, wait a minute, Wilf said Icc is *much* lower at 2V.
Maybe I should look around for relevant data or do a test, like he
did."
Anyway, I didn't intend to simplify. In fact, I usually try to
show the importance of making one's analysis as complete as
possible. If the posting you refer to gave a different impression,
that's regrettable.
Best,
Steve
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# sbolt@xs4all.nl # Steven Bolt # popular science monthly KIJK #
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