Well, I know this has been covered before, but a stroll 
through the archive didn't seem to find a direct answer.  
So here goes once again:

I'm building a circuit using 74HC discrete logic (and a 
16F872, to keep this on topic) and have become ever more 
confused by all the 74xx families that seem to exist.  In 
my particular circuit, a 74HC132 demands 275 microamps of 
5-volt power when handling a 1 MHz signal.  But at 50 MHz 
(Yikes!) the power consumption goes up to a whopping 12.9 
milliamps.  Too much.  Batteries too dead, too soon.

Now, the first reaction might likely be 'Why are you 
trying to use 74HC parts when you should be using ECL or 
discrete transistors or ...'  The answer is, mostly, that 
this is a learning experience and I'd like to get a better 
understanding of all the options.  So here's my question:  
Which of the 5-volt 74xx families might give the best 
performance in terms of lower power consumption at 
(insanely) high frequencies?  74F? 74AC? 74somethingelse?
Maybe someone could point me towards a chart comparing the 
different varieties, if such a thing exists?

This is a one-off exercise, and migrating down to lower 
voltage logic really isn't an option here, even though 
that's what I would do if this were a commercial design.

Brian Aase



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