74 series

The 74 series are a pervasive family of TTL integrated circuits. Originally created by Texas Instruments, eventually all the major IC producers offered compatibly-numbered lines.

Originally offered in DIP and 'flat pak' forms, they are now available in surface mount form as well.

Families

The original 74 series chips (which have numbers of the form '74xx') were joined over time by many other compatible families. '74H' used more power, but were faster; '74L' use less, and were slower. '74S' (using Schottky circuits) which were faster followed, along with '74LS' (low-power Schottky), not as fast as 74S, but using less power. Later '74AS' ('Advanced Schottky) and '74ALS' were added.

The following table gives typical propogation delay (in nsec) and power consumption (in mW):

Family	Speed	Power
Original	10	10
H	6	22
L	33	1
S	3	19
LS	10	2
AS	2	8
ALS	4	1