CMOS Compatability Question

[Paul Schreiber]

1) If you are replacing 74LS, use 74HCT.
2) 4000 series, HC, and AC are all true CMOS: their input level for a '1' is 2/3s of the VCC voltage. Also 4000 series has:

wacky pinouts
low output drive
very slow

but it has 2 great advantages

very very low power, especially 'static' logic (I once ran 143 chips off of 10ma)
can run off +9V batteries, or 4 AA's without a voltage regulator for months on end

The 74C was an attempt by National Semiconductor to steal 4000 business away from Motorola by having the same pinouts as LS. Didn't fly, because of issue (2).

Paul Schreiber
Synthesis Technology

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From: 	A.S.P.[SMTP:ms20 at serv.net]
Sent: 	Saturday, March 22, 1997 7:21 PM
To: 	synth-diy
Subject: 	CMOS Compatability Question


Can anybody give me a quick rundown of what type of logic families are
compatible with each other.  I think the 74Cxx series will work with the
CD4xxx series ok.  Are there any others?  

Romeo