Transistor-Transistor Logic

(TTL) A common semiconductor technology for building discrete digital logic integrated circuits.

It originated from Texas Instruments in 1965.

There have been several series of TTL logic:

7400: 10 ns propagation time, 10 mW/gate power consumption, obsolete;

74L00: Low power: higher resistances, less dissipation (1 mW), longer propagation time (30 ns);

74H00: High power: lower resistances, more dissipation: less sensitivity for noise;

74S00: Schottky-clamped: faster switching (3 ns, 19 mW) by using Schottky diodes to prevent the transistors from saturation;

74LS00: Low power, Schottky-clamped (10 ns, 2 mW);

74AS00: Advanced Schottky: faster switching, less dissipation, (1.5 ns, 10 mW);

74ALS00: Advanced Low power Schottky (4 ns, 1.3 mW).

For each 74xxx family there is a corresponding 54xxx family. The 74 series are specified for operation at 0 - 70 C whereas the 54 (military) series can operate at -55 - 125 C

See also CMOS, ECL.

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