Alt-BEAM Archive
Message #00226
To: BEAM mailing list beam@corp.sgi.com
From: Michael Kennan kennanm@efn.org
Date: Fri, 5 Feb 1999 23:54:27 -0800 (PST)
Subject: [alt-beam] Re: Schmitt trigger
> Anyway, as for the single gate chips, I like the idea, and I can't imagine a
> company not taking advantage of such an opportunity. with devices shrinking,
> every bit of board space is crucial.
When I first started in electrical engineering, I said the same thing...
but it wasn't true. Sure, the need for smaller and smaller components
exists, but that is why there are FPGAs and GALs and ASICs, so you can add
just one more gate without impacting space. This is still mostly true,
but:
There have been a number of letters recently about this, and every one of
them said 'I think these should exist', but not one of them said they
looked it up on the web, which never ceases to amaze me... so I did a
search for 'surface mount single inverter' and got the following as the
first hit:
http://www.fairchildsemi.com/pf/NC/NC7S14.html
These are available in SOT-23 or SC-70 packaging. Interestingly, these
are *5* pin devices... probably so they don't get put in backwards, though
the extra pin and increased size probably make the thing more realistic to
handle. The SOT-23s are about 2.9x2.9mm (body is 1.6x2.9mm), while the
SC-70s are 1.9x2mm (body is 1.25x2mm). Generic packaging information on
the two sizes can be found at
SOT-23: http://www.fairchildsemi.com/products/logic/pdf/ma05b.pdf
SC-70 : http://www.fairchildsemi.com/products/logic/pdf/maa05a.pdf
They are very spendy compared to hex packages... for our purposes, they
are probably best used for aesthetic reasons or for cases where boards
space costs more than the gate price delta.
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