The
7400 series of
Transistor-transistor logicTransistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...
(TTL)
integrated circuitIn electronics, an integrated circuit is a miniaturized electronic circuit that has been manufactured in the surface of a thin substrate of semiconductor material...
s are historically important as the first widespread
familyIn computer engineering, a logic family may refer to one of two related concepts. A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compatible logic levels and power supply...
of TTL integrated circuit logic . It was used to build the mini and mainframe computers of the 1960s and 1970s. Several generations of
pin-compatibleIn electronics, a pin-compatible device, such as a logic integrated circuit , memory module or microprocessor, is one that has the same functions assigned to the same particular pins....
descendants of the original family have since been de-facto
standard components.
Overview
The 7400 series contains hundreds of devices that provide everything from basic logic gates,
flip-flopIn digital circuits, a flip-flop is a term referring to an electronic circuit that has two stable states and thereby is capable of serving as one bit of memory...
s, and counters, to special purpose bus transceivers and Arithmetic Logic Units (ALU). Specific functions are described in a
list of 7400 series integrated circuits.
Today, surface-mounted CMOS versions of the 7400 series are used in various applications in electronics and for
glue logicIn electronics, glue logic is the custom electronic circuitry needed to achieve compatible interfaces between two different off-the-shelf integrated circuits...
in computers and industrial electronics. The fastest parts are surface-mount only. Through-hole devices in
dual in-line packageIn microelectronics, a dual in-line package , sometimes called a DIL package, is an electronic device package with a rectangular housing and two parallel rows of electrical connecting pins. The pins are all parallel, point downward, and extend past the bottom plane of the package at least enough...
s (DIP) were the mainstay of the industry for many decades. DIP devices are very useful for rapid
breadboardA breadboard is a construction base for a one-of-a-kind electronic circuit, a prototype. In modern times the term is commonly used to refer to a particular type of breadboard, the solderless breadboard ....
-prototyping and education and remain available for many part numbers.
The 14-pin DIP shown to the right is an example of a 7400 part. The chip contains four two-input
NAND gateThe NAND gate is a digital logic gate that behaves in a manner that corresponds to the truth table to the left. A LOW output results only if both the inputs to the gate are HIGH. If one or both inputs are LOW, a HIGH output results...
s. Each gate uses two pins for input and one pin for its output, and the remaining two contacts supply power (+5 V) and connect the ground. (The former
Soviet UnionThe Union of Soviet Socialist Republics was a constitutionally socialist state that existed in Eurasia from 1922 to 1991. The name is a translation of the , tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik, abbreviated СССР, SSSR. The common short name is Soviet Union, from , Sovetskiy Soyuz...
manufactured the K155ЛA3 which was pin-compatible with the 7400 part available in the United States, except for using a metric spacing of 2.5mm between pins instead of the 1/10"based (2.54mm) spacing used in the west.)
While designed as a family of digital logic, it was not unusual to see TTL chips in analog circuits like
Schmitt triggerIn electronics, a Schmitt trigger is a comparator circuit that incorporates positive feedback.When the input is higher than a certain chosen threshold, the output is high; when the input is below another chosen threshold, the output is low; when the input is between the two, the output retains its...
s. Like the
4000 seriesThe 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology. They were introduced by RCA as CD4000 COS/MOS in 1968, as a lower power and more versatile alternative to the 7400 series of...
, the newer
CMOSComplementary metal–oxide–semiconductor is a technology for making integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for a wide variety of analog circuits such as image sensors, data...
versions of the 7400 series are also usable as analog amplifiers using negative feedback (similar to
operational amplifierAn operational amplifier, which is often called an op-amp, is a DC-coupled high-gain electronic voltage amplifier with differential inputs and, usually, a single output...
s with only an inverting input).
7400 series derivative families
7400 series parts were constructed using bipolar transistors. Newer series, more or less compatible in function and logic level with the original parts, use
CMOSComplementary metal–oxide–semiconductor is a technology for making integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for a wide variety of analog circuits such as image sensors, data...
technology or a combination of the two (
BiCMOSIn integrated circuit technologies, BiCMOS, also called BiMOS, refers to the integration of bipolar junction transistors and CMOS technology into a single integrated circuit device. This technology has commercial application in amplifier and discrete component logic design...
). Originally the bipolar circuits provided higher speed but consumed more power than the competing
4000 seriesThe 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology. They were introduced by RCA as CD4000 COS/MOS in 1968, as a lower power and more versatile alternative to the 7400 series of...
of CMOS devices. Bipolar devices are also limited to a fixed power supply voltage, typically 5V, 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 manufactured radiation-hardened devices with the prefix
RSN, and the company offered beam-lead bare dice for integration into hybrid circuits with a
BL prefix designation.
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 as
MullardMullard Limited was a British manufacturer of electronic components. The Mullard Radio Valve Co. Ltd. of Southfields, London, was founded in 1920 by Captain Stanley R. Mullard, who had previously designed valves for the Admiralty before becoming managing director of the Z Electric Lamp Co. The...
listed 6400-series compatible parts in 1970 data sheets , by 1973 there was no mention of the 6400 family in the Texas Instruments
TTL Data Book. 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. Strictly, an integrated circuit made in CMOS is no longer a TTL chip since it uses FETs and not bipolar junction transistors, 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
.
- Bipolar
- 74 - the "standard TTL" logic family had no letters between the "74" and the specific part number.
- 74L - Low power (compared to the original TTL logic family), very slow
- H - High speed (still produced but generally superseded by the S-series, used in 1970s era computers)
- S - Schottky
The Schottky diode is a semiconductor diode with a low forward voltage drop and a very fast switching action...
(obsolete)
- LS - Low Power Schottky
- AS - Advanced Schottky
- ALS - Advanced Low Power Schottky
- F - Fast (faster than normal Schottky, similar to AS)
- CMOS
- C - CMOS 4-15V operation similar to buffered 4000 (4000B) series
- HC - High speed CMOS, similar performance to LS, 12nS
- HCT - High speed, compatible logic levels to bipolar parts
- AC - Advanced CMOS, performance generally between S and F
- AHC - Advanced High-Speed CMOS, three times as fast as HC
- ALVC - Low voltage - 1.65 to 3.3V, tpd 2nS
- AUC - Low voltage - 0.8 to 2.7V, tpd<1.9nS@1.8V
- FC - Fast CMOS, performance similar to F
- LCX - CMOS with 3V supply and 5V tolerant inputs
- LVC - Low voltage - 1.65 to 3.3V and 5V tolerant inputs, tpd<5.5nS@3.3V, tpd<9nS@2.5V
- LVQ - Low voltage - 3.3V
- LVX - Low voltage - 3.3V with 5V tolerant inputs
- VHC - Very High Speed CMOS - 'S' performance in CMOS technology and power
- G - Super high speeds at more than 1 GHz (Produced by Potato Semiconductor)
- BiCMOS
- BCT - BiCMOS, TTL compatible input thresholds, used for buffers
- ABT - Advanced BiCMOS, TTL compatible input thresholds, faster than ACT and BCT
Many parts in the CMOS HC, AC, and FC families are also offered in "T" versions (HCT, ACT, and FCT) which have input thresholds that are compatible with both TTL and 3.3V CMOS signals. The non-T parts have conventional CMOS input thresholds.
The 74H family is the same basic design as the 7400 family with resistor values reduced. This reduced the typical propagation delay from 9ns to 6ns 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
The 74S family, using
SchottkyThe Schottky diode is a semiconductor diode with a low forward voltage drop and a very fast switching action...
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.
The 74F family was introduced by
Fairchild SemiconductorPresent day Fairchild Semiconductor International, Inc. is a spin-off company resulting from reconstitution of assets in National Semiconductor. It inherits the Fairchild name of the original Fairchild Camera and Instrument Corporation, which had been the cornerstone of the semiconductor industry...
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 family were introduced to support the lower operating voltages used in newer
CPUThe Central Processing Unit or processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. This term has been in use in the computer industry at least since the early 1960s...
devices.
History
Although the 7400 series was the first
de facto industry standard TTL logic family, second-sourced by several semiconductor companies, there were earlier TTL logic families such as the
SylvaniaSylvania literally means "forest land" in Latin. It is used to mean several different things:- Companies :* Sylvania Electric Products, former North American electric and electronics firm, forerunner to Osram Sylvania...
SUHL family,
MotorolaMotorola, Inc. is an American, multinational, Fortune 100, telecommunications company based in Schaumburg, Illinois. It is a manufacturer of wireless telephone handsets, and also designs and sells wireless network infrastructure equipment such as cellular transmission base stations and signal...
MC4000 MTTL family (not to be confused with RCA
CD4000The 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology. They were introduced by RCA as CD4000 COS/MOS in 1968, as a lower power and more versatile alternative to the 7400 series of...
CMOS), the
National SemiconductorNational Semiconductor is a semiconductor manufacturer, specializing in analog devices and subsystems,headquartered in Santa Clara, California, USA. The products of National Semiconductor include power management circuits, display drivers, audio and operational amplifiers, communication interface...
DM8000 family,
FairchildPresent day Fairchild Semiconductor International, Inc. is a spin-off company resulting from reconstitution of assets in National Semiconductor. It inherits the Fairchild name of the original Fairchild Camera and Instrument Corporation, which had been the cornerstone of the semiconductor industry...
9300 series, and the
SigneticsSignetics, once a major player in semiconductor manufacturing, made a variety of devices which included integrated circuits, bipolar and MOS, the Dolby circuit, logic, memory and analog circuits and Motorola clone CPUs, some of which were included in the first Atari video games.Signetics was...
8200 family.
The 7400N quad
NANDNAND may stand for:*Logical NAND , a binary operation in logic.**NAND gate, an electronic gate that implements a logical NAND.*NAND Flash Memory, a type of Flash Memory technology. For more information, see Flash memory#NAND flash....
gate was the first product in the series.
The 5400 and 7400 series were used in many popular minicomputers in the Seventies and early Eighties. The DEC
PDPProgrammed Data Processor was the name of a series of minicomputers made by Digital Equipment Corporation. The name 'PDP' intentionally avoided the use of the term 'computer' because at the time of the first PDPs, computers had a reputation of being large, complicated, and expensive machines, and...
series 'minis' used the
74181The 74181 is a bit slice arithmetic logic unit , implemented as a 7400 series TTL integrated circuit. The first complete ALU on a single chip, it was used as the arithmetic/logic core in the CPUs of many historically significant minicomputers and other devices.The 74181 represents an evolutionary...
ALUIn computing, an arithmetic logic unit is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers...
as the main computing element in the
CPUThe Central Processing Unit or processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. This term has been in use in the computer industry at least since the early 1960s...
. Other examples were the
Data General NovaThe Data General Nova was a popular 16-bit minicomputer built by the United States company Data General starting in 1969. The Nova was packaged into a single rack mount case and had enough power to do most simple computing tasks. The Nova became popular in science laboratories around the world, and...
series and
Hewlett-PackardHewlett-Packard Company , commonly referred to as HP, is a technology corporation headquartered in Palo Alto, California, United States. HP has its United States offices at the former old Compaq Campus in unincorporated Harris County, Texas, Latin America offices in Miami-Dade County, Florida,...
21MX, 1000, and 3000 series.
Hobbyists and students equipped with
wire wrapWire wrap is a technique for constructing small numbers of complex electronics assemblies. It is an alternative technique to the use of small runs of printed circuit boards, and has the advantage of being easily changed for prototyping work...
tools, a '
breadboardA breadboard is a construction base for a one-of-a-kind electronic circuit, a prototype. In modern times the term is commonly used to refer to a particular type of breadboard, the solderless breadboard ....
' and a 5-volt
power supplyPower supply is a reference to a source of electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU...
could also experiment with digital logic referring to how-to articles in Byte Magazine and
Popular ElectronicsPopular Electronics was an American magazine started by Ziff-Davis Publishing in October 1954 for hobbyist and experimenters in electronics. It soon became the "World's Largest-Selling Electronics Magazine". The circulation was 240,151 in April 1957 and 400,000 by 1963. Ziff-Davis published Popular...
which featured circuit examples in nearly every issue. In the early days of large-scale IC development, a prototype of a new large-scale integrated circuit might have been developed using TTL chips on several circuit boards, before committing to manufacture of the target device in IC form. This allowed simulation of the finished product and testing of the logic before the availability of software simulations of integrated circuits.
In 1965, typical quantity-one pricing for the SN5400 (Military grade, in ceramic welded
flat-packFlatpack is a US military standardized Printed-circuit-board surface-mount-component package. The military standard MIL-STD-1835C defines: Flat package...
) was around 22 USD.
As of 2007, individual commercial-grade chips in molded epoxy (plastic) packages can be purchased for approximately 0.25 USD each, depending on the particular chip. Purchased in bulk the price per unit falls even lower.
Part numbering scheme
The part numbers for 7400 series logic devices often use the following naming convention, though specifics vary between manufacturers.
- First, although sometimes omitted, a two or three letter prefix which indicates the manufacturer of the device (e.g. SN for Texas Instruments
Texas Instruments , widely known as TI, is an American company based in Dallas, Texas, United States, renowned for developing and commercializing semiconductor and computer technology. TI is the No. 4 manufacturer of semiconductors worldwide after Intel, Samsung and Toshiba, and is the top supplier...
, DM for National SemiconductorNational Semiconductor is a semiconductor manufacturer, specializing in analog devices and subsystems,headquartered in Santa Clara, California, USA. The products of National Semiconductor include power management circuits, display drivers, audio and operational amplifiers, communication interface...
) although these codes are no longer closely associated with a single manufacturer, for example Fairchild SemiconductorPresent day Fairchild Semiconductor International, Inc. is a spin-off company resulting from reconstitution of assets in National Semiconductor. It inherits the Fairchild name of the original Fairchild Camera and Instrument Corporation, which had been the cornerstone of the semiconductor industry...
manufactures parts with MM and DM prefixes, and none.
- A two-figure secondary prefix, of which the two most common are '74', indicating a commercial temperature range device and '54', indicating an extended (military) temperature range
- Up to four letters describing the logic subfamily, as listed above (e.g. 'LS' or 'HCT').
- Two or more digits assigned for each device, e.g. 00 for a quad 2-input NAND gate. There are hundreds of different devices in each family. The allocation of device numbers (and, with a few exceptions, the pin-outs) of the original 7400 family was carried across to the later families, and new numbers allocated for new functions, plus some of the competing CD4000
The 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology. They were introduced by RCA as CD4000 COS/MOS in 1968, as a lower power and more versatile alternative to the 7400 series of...
numbers and pin-outs were included over time. There is no well-defined pattern to the allocation of these numbers, but low numbers tend to be SSI- Engineering :*Soil structure interaction, an interaction between soil and structure during earthquakes- Economics :* Standard Settlement Instructions, payment processing and settlement information about financial institutions...
gates while larger numbers tend to be MSI-Computing:* Microsoft Installer, an installer system written by Microsoft for Windows platforms* Medium Scale Integration, a generation of integrated circuit chips which contain hundreds of transistors* Message Signaled Interrupts, a PCI 2.2 interrupt mechanism...
and more complex functions. The function and pin-out of the chip is nearly always the same for the same device number regardless of subfamily manufacturer – exceptions are discussed below.
- Additional suffix letters and numbers may be attached to indicate the package type, quality grade, or other information, but this varies widely by manufacturer.
For example
SN74ALS245N means this is a device probably made by
Texas InstrumentsTexas Instruments , widely known as TI, is an American company based in Dallas, Texas, United States, renowned for developing and commercializing semiconductor and computer technology. TI is the No. 4 manufacturer of semiconductors worldwide after Intel, Samsung and Toshiba, and is the top supplier...
(SN), it is a commercial temperature range TTL device (74), it is a member of the "advanced low-power Schottky" family (ALS), and it is a
bi-directional eight bit buffer (245) in a plastic through-hole
DIPIn microelectronics, a dual in-line package , sometimes called a DIL package, is an electronic device package with a rectangular housing and two parallel rows of electrical connecting pins. The pins are all parallel, point downward, and extend past the bottom plane of the package at least enough...
package (N).
Many
logic familiesIn computer engineering, a logic family may refer to one of two related concepts. A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compatible logic levels and power supply...
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 replacementIn electronics, a pin-compatible device, such as a logic integrated circuit , memory module or microprocessor, is one that has the same functions assigned to the same particular pins....
") in a circuit, with the same function and pin-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 competing
CD4000BThe 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology. They were introduced by RCA as CD4000 COS/MOS in 1968, as a lower power and more versatile alternative to the 7400 series of...
series, for example. But there are a few exceptions where incompatibilities (mainly in pin-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.
- five versions of the 74x54 (4-Wide AND-OR-INVERT gates IC
In electronics, an integrated circuit is a miniaturized electronic circuit that has been manufactured in the surface of a thin substrate of semiconductor material...
), namely 7454(N), 7454W, 74H54, 74L54W and 74L54N/74LS54, are different from each other in pin-out and/or function!).
Some manufacturers such as Mullard and Siemens had
pin-compatibleIn electronics, a pin-compatible device, such as a logic integrated circuit , memory module or microprocessor, is one that has the same functions assigned to the same particular pins....
TTL parts in the FJ series (e.g. an FJH131 was the equivalent of the 7400) but with a completely different numbering scheme, however, data sheets identified the
7400-compatible number as an aid to recognition.
See also
- List of 7400 series integrated circuits
- 4000 series
The 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology. They were introduced by RCA as CD4000 COS/MOS in 1968, as a lower power and more versatile alternative to the 7400 series of...
- List of 4000 series integrated circuits
- Logic gate
A logic gate performs a logical operation on one or more logic inputs and produces a single logic output. The logic normally performed is Boolean logic and is most commonly found in digital circuits...
- Open collector
Open collector is a type of output on many integrated circuits . Instead of outputting a signal of a specific voltage or current, the output signal is applied to the base of an internal NPN transistor whose collector is externalized on a pin of the IC. The emitter of the transistor is connected...