Editing Transistor–transistor logic (section)

==Sub-types==
Successive generations of technology produced compatible parts with improved power consumption or switching speed, or both. Although vendors uniformly marketed these various product lines as TTL with [[Schottky diode]]s, some of the underlying circuits, such as used in the LS family, could rather be considered [[DTL]].<ref>Ayers, J. [http://people.seas.harvard.edu/~jones/es154/lectures/lecture_7/pdfs/215ln04.pdf UConn EE 215 notes for lecture 4.] Harvard University faculty web page. Archive of web page from University of Connecticut. n.d. Retrieved 17 September 2008.</ref>

Variations of and successors to the basic TTL family, which has a typical gate propagation delay of 10ns and a power dissipation of 10&nbsp;mW per gate, for a [[power–delay product]] (PDP) or [[switching energy]] of about 100 [[joule|pJ]], include:

* Low-power TTL (L), which traded switching speed (33ns) for a reduction in power consumption (1&nbsp;mW) (now essentially replaced by [[CMOS]] logic)
* High-speed TTL (H), with faster switching than standard TTL (6ns) but significantly higher power dissipation (22&nbsp;mW)
* Schottky TTL (S), introduced in 1969, which used [[Schottky diode]] clamps at gate inputs to prevent charge storage and improve switching time.  These gates operated more quickly (3ns) but had higher power dissipation (19&nbsp;mW)
* Low-power Schottky TTL (LS) – used the higher resistance values of low-power TTL and the Schottky diodes to provide a good combination of speed (9.5 ns) and reduced power consumption (2&nbsp;mW), and PDP of about 20 pJ. Probably the most common type of TTL, these were used as glue logic in microcomputers, essentially replacing the former H, L, and S sub-families.
* Fast (F) and Advanced-Schottky (AS) variants of LS from Fairchild and TI, respectively, circa 1985, with "[[Miller effect|Miller]]-killer" circuits to speed up the low-to-high transition.  These families achieved PDPs of 10 pJ and 4 pJ, respectively, the lowest of all the TTL families.
* Low-voltage TTL (LVTTL) for 3.3-volt power supplies and memory interfacing.

Most manufacturers offer commercial and extended temperature ranges: for example Texas Instruments [[7400 series]] parts are rated from 0 to 70&nbsp;°C, and 5400 series devices over the military-specification temperature range of −55 to +125&nbsp;°C.

Special quality levels and high-reliability parts are available for military and aerospace applications.

[[Radiation-hardened]] devices (for example from the SNJ54 series) are offered for space applications.