74lsXXX vs 74XXX chip famies?

[tggzzz]

I also recall those 74xx TTL devices with nostalgia, as I learned the basic logic circuit concepts with them.

Nowadays if I would want to use them, for whatever the reason, I would choose the 74HCxx or 74HCTxx devices instead, which have improved electrical characteristics.

I prefer the HC and HCT families as well, but most of the old test instruments that I repair or improve use the bipolar TTL families.  For mixed signal stuff, the higher voltage 4000 and 74C series are more useful even though they are slow.

Or the 74LVC* devices. Small, fast, drive 50ohms, low inductance PSU leads.

I think LVC is the fastest since it still supports 5 volt power, and it would be my first choice unless the lower voltage stuff is faster.

(Some LVC is apparently only 3.3V)

This kind of discussion is a good example of how TAoE can save a lot of peoples' own time. If readers of this thread haven't got a copy... get one!

From TaOE 3rd edition Section 10.2.3 CMOS and bipolar (“TTL”) characteristics"...
"...Among them, the LVC and 7SZ families are nice, with their 5 V tolerant inputs and good supply voltage ranges (1.8–3.3 V and 1.8–5 V). For operation at 5 V the AHC(T), VHC(T), or LV families are also good choices; their inputs are 5 V tolerant regardless of supply voltage (which can be 2.5–5 V). These parts are available only in surface-mount packages; if you want DIP through-hole parts for ease of  breadboarding, use HC(T) or AC(T)."