[time-nuts] Subs for obsolete chips in pictic
hmurray at megapathdsl.net
Mon Dec 12 04:53:20 EST 2011
> Better use 74HC or 74HCT parts, the 74F should be TTL FAST parts that
> require high input current to be driven correctly.
HC/HCT are pretty slow. I'd carefully check the data sheet timings before
substituting for AC.
Yes, F/FAST requires some input current, but I wouldn't call it "high". It's
higher than CMOS but might work in some cases. Again, check the data sheets.
(Or try it for a low volume project.)
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