Please help with logic IC families...

gstopp at gstopp at
Thu Feb 15 17:48:17 CET 1996

     Don't despair Chris and don't feel alone... new logic families come 
     out faster than most of us can keep up with. I blow up chips on a 
     regular basis and when I look at the part it's something like 
     "74HCTAFLS4067BCDLC44" and so I go dig up the "High-speed CMOS TTL 
     Advanced Fast Low-power Schottkey B-series Plastic PLCC" data book and 
     find out that I was trying to shove +15 volts into a five volt part. 
     Large amounts of thermal release is always a giveaway.
     From memory I can be of little help. I think that the 74HC can go up 
     to about seven volts (like we all have seven volt power supplies!) and 
     the 74HCT4000 guys go only to +5, and the CD4000's go up to +18, but 
     beyond that it's databook time. Sounds like your doohickeys are fine 
     at +15. If they stay cool then you're OK.
     I can look up your HCF4000's if you tell me the manufacturer...
     Good idea for some research and posting. If I find the time maybe I'll 
     put something out.
     - Gene
     gstopp at

______________________________ Reply Separator _________________________________
Subject: Please help with logic IC families...
Author:  Christopher List <Christopher_List at> at ccrelayout
Date:    2/15/96 11:56 AM
- I didn't know what to make of it. Everything I've done so far has been with 
+15v power supplies, and so I've always just ordered 4000 stuff without much 
thought. I usually got CD4000 from the suppliers, used 'em, no problem. So I try
looking this chip up in the book. It's got the  HC line that runs on +5 or +6, 
and the 4000B line that runs on +15  - but nothing with both. So I tried it an 
it works (so far) - but that's never good enough for me. I'm confused and I hate
Should this thing be at +15? Is this some kind of high-speed +15v CMOS. What 
about the 74C -  I see they're 15v as well? But the CD54HC4000A is 5v - right?
Some simple rules of thumb would be greatly appreciated. I always thought the 
major groups of modern IC's were "74" types (5v) and "CD4xxx" types (15v) - but 
The AofE tells me that's not so - and it doesn't clarify some of these 
seemingly "cross-named" IC's. My world is coming apart - all is chaos and 
entropy. Please help...

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