The7400 series is a popularlogic family oftransistor–transistor logic (TTL)integrated circuits (ICs).^[3]

In 1964,Texas Instruments introduced the SN5400 series of logic chips, in a ceramicsemiconductor package. A low-cost plastic package SN7400 series was introduced in 1966 which quickly gained over 50% of the logic chip market, and eventually becomingde facto standardized electronic components.^[4][5] Since the introduction of the original bipolar-transistor TTL parts,pin-compatible parts were introduced with such features as low powerCMOS technology andlower supply voltages.Surface mount packages exist for several popular logic family functions.^[6]

The 7400 series contains hundreds of devices that provide everything from basiclogic gates,flip-flops, and counters, to special purpose bus transceivers andarithmetic logic units (ALU). Specific functions are described in alist of 7400 series integrated circuits. Some TTL parts were made with an extended military-specification temperature range. These parts are prefixed with54 instead of74 in the part number. The less-common64 and84 prefixes onTexas Instruments parts indicated an industrial temperature range. Since the 1970s, new product families have been released to replace the original 7400 series. More recent TTL-compatible logic families were manufactured usingCMOS orBiCMOS technology rather than TTL.

Today,surface-mounted CMOS versions of the 7400 series are used in various applications in electronics and forglue logic in computers and industrial electronics. The originalthrough-hole devices indual in-line packages (DIP/DIL) were the mainstay of the industry for many decades. They are useful for rapidbreadboard-prototyping and for education and remain available from most manufacturers. The fastest types and very low voltage versions are typicallysurface-mount only, however.^{[citation needed]}

The first part number in the series, the 7400, is a 14-pin IC containing four two-inputNAND gates. Each gate uses two input pins and one output pin, with the remaining two pins being power (+5 V) and ground. This part was made in various through-hole and surface-mount packages, including flat pack and plastic/ceramic dual in-line. Additional characters in a part number identify the package and other variations.

Unlike the olderresistor-transistor logic integrated circuits, bipolar TTL gates were unsuitable to be used as analog devices, providing low gain, poor stability, and low input impedance.^[7] Special-purpose TTL devices were used to provide interface functions such asSchmitt triggers ormonostable multivibrator timing circuits. Inverting gates could be cascaded as aring oscillator, useful for purposes where high stability was not required.

Although the 7400 series was the firstde facto industry standard TTL logic family (i.e. second-sourced by several semiconductor companies), there were earlier TTL logic families such as:

• Sylvania Universal High-level Logic in 1963^[8][9][10]
• Motorola MC4000 MTTL^[11][12][13]
• National Semiconductor DM8000^{[14][better source needed]}
• Fairchild 9300 series^[15][16]
• Signetics 8200 and 8T00^[13][15][17]

The 7400 quad 2-inputNAND gate was the first product in the series, introduced byTexas Instruments in a military grade metalflat package (5400W) in October 1964. The pin assignment of this early series differed from thede facto standard set by the later series inDIP packages (in particular, ground was connected to pin 11 and the power supply to pin 4, compared to pins 7 and 14 for DIP packages).^[5] The extremely popular commercial grade plasticDIP (7400N) followed in the third quarter of 1966.^[18]

The 5400 and 7400 series were used in many popularminicomputers in the 1970s and early 1980s. Some models of the DECPDP-series "minis" used the74181ALU as the main computing element in theCPU. Other examples were theData General Nova series andHewlett-Packard 21MX, 1000, and 3000 series.

In 1965, typical quantity-one pricing for the SN5400 (military grade, in ceramic weldedflat-pack) was around 22USD.^[19] As of 2007, individual commercial-grade chips in molded epoxy (plastic) packages can be purchased for approximately US$0.25 each, depending on the particular chip.

• 
  Die of a 74AHC00D, manufactured byNXP
• 
  SN7400 die in the original flat package, manufactured byTI
• 
  Die vs Schematic of a NAND gate in a 74H00 (Darlington transistor is visbile on the right)
• 
  Schematic of one gate in a 7400
• 
  Schematic of one gate in a 74LS00
• 
  Schematic of one gate in a 74ALS00
• 
  Size comparison of 74HC00 in DIP vs TSSOP package

7400 series parts were constructed usingbipolar junction transistors (BJT), forming what is referred to astransistor–transistor logic orTTL. Newer series, more or less compatible in function and logic level with the original parts, useCMOS technology or a combination of the two (BiCMOS). Originally the bipolar circuits provided higher speed but consumed more power than the competing4000 series of CMOS devices. Bipolar devices are also limited to a fixed power-supply voltage, typically 5 V, while CMOS parts often support a range of supply voltages.

Milspec-rated devices for use in extended temperature conditions are available as the 5400 series. Texas Instruments also manufacturedradiation-hardened devices with the prefixRSN, and the company offeredbeam-lead bare dies for integration into hybrid circuits with aBL prefix designation.^[20]

Regular-speed TTL parts were also available for a time in the 6400 series – these had an extended industrial temperature range of −40 °C to +85 °C. While companies such asMullard listed 6400-series compatible parts in 1970 data sheets,^[21] by 1973 there was no mention of the 6400 family in the Texas InstrumentsTTL Data Book. Texas Instruments brought back the 6400 series in 1989 for the SN64BCT540.^[22] The SN64BCTxxx series is still in production as of 2023.^[23] Some companies have also offered industrial extended temperature range variants using the regular 7400-series part numbers with a prefix or suffix to indicate the temperature grade.

As integrated circuits in the 7400 series were made in different technologies, usually compatibility was retained with the original TTL logic levels and power-supply voltages. An integrated circuit made in CMOS is not a TTL chip, since it usesfield-effect transistors (FETs) and not bipolar junction transistors (BJT), but similar part numbers are retained to identify similar logic functions and electrical (power and I/O voltage) compatibility in the different subfamilies.

Over 40 different logic subfamilies use this standardized part number scheme.^{[6][page needed]} The headings in the following table are:V_cc – power-supply voltage;t_pd – maximum gate delay;I_OL – maximum output current at low level;I_OH – maximum output current at high level;t_pd,I_OL, andI_OH apply to most gates in a given family. Driver or buffer gates have higher output currents.

Many parts in the CMOS HC, AC, AHC, and VHC families are also offered in "T" versions (HCT, ACT, AHCT and VHCT) which have input thresholds that are compatible with both TTL and 3.3 V CMOS signals. The non-T parts have conventional CMOS input thresholds, which are more restrictive than TTL thresholds. Typically, CMOS input thresholds require high-level signals to be at least 70% of Vcc and low-level signals to be at most 30% of Vcc. (TTL has the input high level above 2.0 V and the input low level below 0.8 V, so a TTL high-level signal could be in the forbidden middle range for 5 V CMOS.)

The 74H family is the same basic design as the 7400 family with resistor values reduced. This reduced the typicalpropagation delay from 9 ns to 6 ns but increased the power consumption. The 74H family provided a number of unique devices for CPU designs in the 1970s. Many designers of military and aerospace equipment used this family over a long period and as they need exact replacements, this family is still produced by Lansdale Semiconductor.^[102]

The 74S family, usingSchottky circuitry, uses more power than the 74, but is faster. The 74LS family of ICs is a lower-power version of the 74S family, with slightly higher speed but lower power dissipation than the original 74 family; it became the most popular variant once it was widely available. Many 74LS ICs can be found in microcomputers and digital consumer electronics manufactured in the 1980s and early 1990s.

The 74F family was introduced byFairchild Semiconductor and adopted by other manufacturers; it is faster than the 74, 74LS and 74S families.

Through the late 1980s and 1990s newer versions of this^[which?] family were introduced to support the lower operating voltages used in newerCPU devices.

Part number schemes varied by manufacturer. The part numbers for 7400-series logic devices often use the following designators:

• Often first, a two or three letter prefix, denoting the manufacturer and flow class of the device. These codes are no longer closely associated with a single manufacturer, for example,Fairchild Semiconductor manufactures parts with MM and DM prefixes, and no prefixes. Examples:
  • SN:Texas Instruments using a commercial processing
  • SNV: Texas Instruments using military processing
  • M:ST Microelectronics
  • DM:National Semiconductor
  • UT:Cobham PLC
  • SG:Sylvania
  • RD:RIFA AB
• Two digits for temperature range. Examples:
  • 54: military temperature range
  • 64: short-lived historical series with intermediate "industrial" temperature range
  • 74: commercial temperature range device
• Zero to four letters denoting the logic subfamily. Examples:
  • zero letters: basic bipolar TTL
  • LS: low power Schottky
  • HCT: High-speed CMOS compatible with TTL
• Two or more arbitrarily assigned digits that identify the function of the device. There arehundreds of different devices in each family.
• Additional suffix letters and numbers may be appended to denote the package type, quality grade, or other information, but this varies widely by manufacturer.

For example, "SN5400N" signifies that the part is a 7400-series IC probably manufactured byTexas Instruments ("SN" originally meaning "Semiconductor Network"^[104]) using commercial processing, is of the military temperature rating ("54"), and is of the TTL family (absence of a family designator), its function being thequad 2-input NAND gate ("00") implemented in a plastic through-holeDIP package ("N").

Manylogic families maintain a consistent use of the device numbers as an aid to designers. Often a part from a different 74x00 subfamily could be substituted ("drop-in replacement") in a circuit, with the same function andpin-out yet more appropriate characteristics for an application (perhaps speed or power consumption), which was a large part of the appeal of the 74C00 series over the competingCD4000B series, for example. But there are a few exceptions where incompatibilities (mainly inpin-out) across the subfamilies occurred, such as:

• some flat-pack devices (e.g. 7400W) and surface-mount devices,
• some of the faster CMOS series (for example 74AC),
• a few low-power TTL devices (e.g. 74L86, 74L9 and 74L95) have a different pin-out than the regular (or even 74LS) series part.^[105]
• five versions of the 74x54 (4-wide AND-OR-INVERT gatesIC), namely 7454(N), 7454W, 74H54, 74L54W and 74L54N/74LS54, are different from each other inpin-out and/or function,^[106]

Some manufacturers, such as Mullard and Siemens, hadpin-compatible TTL parts, but with a completely different numbering scheme; however, data sheets identified the7400-compatible number as an aid to recognition.

At the time the 7400 series was being made, some European manufacturers (that traditionally followed thePro Electron naming convention), such asPhilips/Mullard, produced a series of TTL integrated circuits with part names beginning with FJ. Some examples of FJ series are:

• FJH101 (=7430) single 8-input NAND gate,
• FJH131 (=7400) quadruple 2-input NAND gate,
• FJH181 (=7454N or J) 2+2+2+2 input AND-OR-NOT gate.

TheSoviet Union started manufacturing TTL ICs with 7400-series pinout in the late 1960s and early 1970s, such as the K155ЛA3, which was pin-compatible with the 7400 part available in the United States, except for using a metric spacing of 2.5 mm between pins instead of the 0.1 inches (2.54 mm) pin-to-pin spacing used in the west.^[107]Another peculiarity of the Soviet-made 7400 series was the packaging material used in the 1970s–1980s. Instead of the ubiquitous black resin, they had a brownish-green body colour with subtle swirl marks created during the moulding process. It was jokingly referred to in the Eastern Bloc electronics industry as the "elephant-dung packaging", due to its appearance.^{[citation needed]}

TheSoviet integrated circuit designation is different from the Western series:

• the technology modifications were considered different series and were identified by different numbered prefixes – К155 series is equivalent to plain 74, К555 series is 74LS, К1533 is 74ALS, etc.;
• the function of the unit is described with a two-letter code followed by a number:
  • the first letter represents the functional group – logical, triggers, counters, multiplexers, etc.;
  • the second letter shows the functional subgroup, making the distinction between logical NAND and NOR, D- and JK-triggers, decimal and binary counters, etc.;
  • the number distinguishes variants with different number of inputs or different number of elements within a die – ЛА1/ЛА2/ЛА3 (LA1/LA2/LA3) are 2 four-input / 1 eight-input / 4 two-input NAND elements respectively (equivalent to 7420/7430/7400).

Before July 1974 the two letters from the functional description were inserted after the first digit of the series. Examples: К1ЛБ551 and К155ЛА1 (7420), К1ТМ552 and К155ТМ2 (7474) are the same ICs made at different times.

Clones of the 7400 series were also made in otherEastern Bloc countries:^[108]

• Bulgaria (MikroelektronikaBotevgrad) used a designation somewhat similar to that of the Soviet Union, e.g.1ЛБ00ШМ (1LB00ShM) for a 74LS00. Some of the two-letter functional groups were borrowed from the Soviet designation, while others differed. Unlike the Soviet scheme, the two or three digit number after the functional group matched the western counterpart. The series followed at the end (i.e.ШМ for LS). Only the LS series is known to have been manufactured in Bulgaria.^{[109][110]: 8–11}
• Czechoslovakia (TESLA) used the 7400 numbering scheme with manufacturer prefix MH. Example: MH7400. Tesla also produced industrial grade (8400, −25 ° to 85 °C) and military grade (5400, −55 ° to 125 °C) ones.
• Poland (Unitra CEMI) used the 7400 numbering scheme with manufacturer prefixes UCA for the 5400 and 6400 series, as well as UCY for the 7400 series. Examples: UCA6400, UCY7400. Note that ICs with the prefix MCY74 correspond to the4000 series (e.g. MCY74002 corresponds to 4002 and not to 7402).
• Hungary (Tungsram, later Mikroelektronikai Vállalat / MEV) also used the 7400 numbering scheme, but with manufacturer suffix – 7400 is marked as 7400APC.
• Romania (I.P.R.S.) used a trimmed 7400 numbering with the manufacturer prefix CDB (example: CDB4123E corresponds to 74123) for the 74 and 74H series, where the suffixH indicated the 74H series.^[111] For the later 74LS series, the standard numbering was used.^[112]
• East Germany (HFO) also used trimmed 7400 numbering without manufacturer prefix or suffix. The prefix D (or E) designates digital IC, and not the manufacturer. Example: D174 is 7474. 74LS clones were designated by the prefix DL; e.g. DL000 = 74LS00. In later years East German made clones were also available with standard 74* numbers, usually for export.^[113]

A number of different technologies were available from the Soviet Union,^{[107][114][115][116][108]}Czechoslovakia,^[117][110]Poland,^[108][110] and East Germany.^[113] The 8400 series in the table below indicates an industrial temperature range from −25 °C to +85 °C (as opposed to −40 °C to +85 °C for the 6400 series).

Around 1990 the production of standard logic ceased in all Eastern European countries except the Soviet Union and laterRussia andBelarus. As of 2016, the series 133, К155, 1533, КР1533, 1554, 1594, and 5584 were in production at "Integral" in Belarus,^[118]as well as the series 130 and 530 at "NZPP-KBR",^[119]134 and 5574 at "VZPP",^[120]533 at"Svetlana",^[121]1564, К1564, КР1564 at "NZPP",^[122]1564, К1564 at "Voshod",^[123]1564 at "Exiton",^[124]and 133, 530, 533, 1533 at"Mikron" in Russia.^[125]The Russian companyAngstrem manufactures 54HC circuits as the 5514БЦ1 series, 54AC as the 5514БЦ2 series, and 54LVC as the 5524БЦ2 series.^[126]As of 2024, the 133, 136, and 1533 series are in production at Kvazar Kyiv in Ukraine.^[127]

Books

• 50 Circuits Using 7400 Series IC's; 1st Ed; R.N. Soar; Bernard Babani Publishing; 76 pages; 1979;ISBN 0900162775.(archive)
• TTL Cookbook; 1st Ed;Don Lancaster; Sams Publishing; 412 pages; 1974;ISBN 978-0672210358.(archive)
• Designing with TTL Integrated Circuits; 1st Ed; Robert Morris, John Miller; Texas Instruments and McGraw-Hill; 322 pages; 1971;ISBN 978-0070637450.(archive)

App Notes

• Understanding and Interpreting Standard-Logic Data Sheets; Stephen Nolan, Jose Soltero, Shreyas Rao; Texas Instruments; 60 pages; 2016.
• Comparison of 74HC / 74S / 74LS / 74ALS Logic; Fairchild; 6 pages, 1983.
• Interfacing to 74HC Logic; Fairchild; 10 pages; 1998.
• 74AHC / 74AHCT Designer's Guide; TI; 53pages; 1998. Compares 74HC / 74AHC / 74AC (CMOS I/O) and 74HCT / 74AHCT / 74ACT (TTL I/O).

Fairchild Semiconductor / ON Semiconductor

• Historical Data Books:TTL (1978, 752 pages),FAST (1981, 349 pages)
• Logic Selection Guide (2008, 12 pages)

Nexperia / NXP Semiconductor

• Logic Selection Guide (2020, 234 pages)
• Logic Application Handbook Design Engineer's Guide' (2021, 157 pages)
• Logic Translators' (2021, 62 pages)

Texas Instruments / National Semiconductor

• Historical Catalog:(1967, 375 pages)
• Historical Databooks:TTL Vol1 (1984, 339 pages),TTL Vol2 (1985, 1402 pages),TTL Vol3 (1984, 793 pages),TTL Vol4 (1986, 445 pages)
• Digital Logic Pocket Data Book (2007, 794 pages),Logic Reference Guide (2004, 8 pages),Logic Selection Guide (1998, 215 pages)
• Little Logic Guide (2018, 25 pages),Little Logic Selection Guide (2004, 24 pages)

Toshiba

• General-Purpose Logic ICs (2012, 55 pages)

Wikimedia Commons has media related to7400 Series.

• Understanding 7400-series digital logic ICs - Nuts and Volts magazine
• Thorough list of 7400-series ICs - Electronics Club

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