Pin-compatibility
Encyclopedia
In electronics
, a pin-compatible device, such as a logic integrated circuit
(IC), memory module or microprocessor
, is one that has the same functions assigned to the same particular pins.
There are several levels of compatibility in integrated circuit
s (ICs). Strictly speaking, "pin-compatible" refers only to two chips that have the same functions assigned to the same pins. For instance, two logic chips would have their inputs, outputs, power supply, and ground connections on the same pins.
Generally the term "pin compatibility" (or "pin-for-pin replacement") also presumes mechanical and a significant degree of electrical compatibility, and the expression "pin-compatible" is often used as shorthand to refer to compatibility in all three of these senses, although terms such as "drop-in replacement" or "equivalent device" or "exact replacement" imply more certain compatibility.
ICs are mechanically compatible if they can be inserted into the same socket or soldered to the same footprint. This is generally true only if they use the same packaging standard (e.g. DIP
, TO-220, TSOP
, etc.). Small details can be important, such as a ceramic dual-in-line package being slightly higher than the plastic counterpart may mean devices that are pin-compatible and electrically compatible still not being able to be always be used interchangeably in some high density equipment.
Electrical compatibility implies that the ICs work with the same supply and signaling voltage levels; that one is a suitable replacement for another (perhaps in a particular circuit
, or in general). What constitutes electrical compatibility (and indeed pin compatibility) varies considerably in popular usage; be aware there may still be differences in:
and so on. One Integrated Circuit
may be able to replace another in a particular circuit, with a particular supply voltage for instance, yet the two are not perfectly interchangeable (e.g. a 74HCT00 could not safely be used in a 6V circuit designed for a 74HC00 or 74C00). Careful checking of manufacturer's datasheets remains important even when one device is said to be a pin-for-pin replacement for another.
The most widely used and recognized family of pin-compatible chips is the 74'xx series
of logic ICs (although there are a small number of pin-out incompatibilities). The tick-mark here represents the omitted subfamily designator -- most commonly HC (high-speed CMOS
), but can also be blank (original TTL), C (CMOS), LS (low-power Schottky
), and many others. The "xx" represents the actual part, and ranges from 00 (quad 2-input NAND
) to 40103 (8-bit synchronous binary down counter
). All of the various families have remained pin-compatible over several decades of production by numerous different companies, including some versions that were not electrically compatible. Exceptions are few, but include the 7400N (or 74LS00J/N/W) vs the 7400W; the 7454(J or N) compared with 7454W, 74H54, 74LS54 and 74L54W (five different 4-wide AND-OR-INVERT gate combinations of pin-out and logic function for the same device number). Ironically (given the history of competition between the two logic series), the 74HC series has grown to include pin-compatible versions of several members of the 4000 series
chips, such as the 74HC4051.
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
, a pin-compatible device, such as a logic integrated circuit
Logic gate
A logic gate is an idealized or physical device implementing a Boolean function, that is, it performs a logical operation on one or more logic inputs and produces a single logic output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and...
(IC), memory module or microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
, is one that has the same functions assigned to the same particular pins.
There are several levels of compatibility in integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
s (ICs). Strictly speaking, "pin-compatible" refers only to two chips that have the same functions assigned to the same pins. For instance, two logic chips would have their inputs, outputs, power supply, and ground connections on the same pins.
Generally the term "pin compatibility" (or "pin-for-pin replacement") also presumes mechanical and a significant degree of electrical compatibility, and the expression "pin-compatible" is often used as shorthand to refer to compatibility in all three of these senses, although terms such as "drop-in replacement" or "equivalent device" or "exact replacement" imply more certain compatibility.
ICs are mechanically compatible if they can be inserted into the same socket or soldered to the same footprint. This is generally true only if they use the same packaging standard (e.g. DIP
Dual in-line package
In microelectronics, a dual in-line package is an electronic device package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board or inserted in a socket.A DIP is usually referred to as a DIPn, where n is...
, TO-220, TSOP
Thin small-outline package
Thin small-outline packages, or TSOPs are a type of surface mount IC package. They are notably very low-profile and have tight lead spacing ....
, etc.). Small details can be important, such as a ceramic dual-in-line package being slightly higher than the plastic counterpart may mean devices that are pin-compatible and electrically compatible still not being able to be always be used interchangeably in some high density equipment.
Electrical compatibility implies that the ICs work with the same supply and signaling voltage levels; that one is a suitable replacement for another (perhaps in a particular circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
, or in general). What constitutes electrical compatibility (and indeed pin compatibility) varies considerably in popular usage; be aware there may still be differences in:
- operating temperatureOperating temperatureAn operating temperature is the temperature at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the...
range and the guarantee of various characteristics over a wide temperature range - speed (for logic circuits; bandwidth for analog circuits)
- power supply current demand or working voltage range; the 74HC family of chips can run on 2V to 6V supplies, while the 74HCT family only tolerates 4.5V to 5.5V
and so on. One Integrated Circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
may be able to replace another in a particular circuit, with a particular supply voltage for instance, yet the two are not perfectly interchangeable (e.g. a 74HCT00 could not safely be used in a 6V circuit designed for a 74HC00 or 74C00). Careful checking of manufacturer's datasheets remains important even when one device is said to be a pin-for-pin replacement for another.
The most widely used and recognized family of pin-compatible chips is the 74'xx series
7400 series
The 7400 series of transistor-transistor logic integrated circuits are historically important as the first widespread family of TTL integrated circuit logic. It was used to build the mini and mainframe computers of the 1960s and 1970s...
of logic ICs (although there are a small number of pin-out incompatibilities). The tick-mark here represents the omitted subfamily designator -- most commonly HC (high-speed CMOS
CMOS
Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...
), but can also be blank (original TTL), C (CMOS), LS (low-power Schottky
Schottky
Notable people named Schottky include:* Ernst Max Schottky, botanist* Walter H. Schottky, physicist* Friedrich Schottky, mathematicianOther links:* Schottky diode and Schottky barrier in electronics and physics* Schottky transistor in electronics...
), and many others. The "xx" represents the actual part, and ranges from 00 (quad 2-input NAND
Nand
NAND may stand for:*Nand , an Indian classical raga.*Logical NAND , a binary operation in logic.**NAND gate, an electronic gate that implements a logical NAND....
) to 40103 (8-bit synchronous binary down counter
Counter
In digital logic and computing, a counter is a device which stores the number of times a particular event or process has occurred, often in relationship to a clock signal.- Electronic counters :...
). All of the various families have remained pin-compatible over several decades of production by numerous different companies, including some versions that were not electrically compatible. Exceptions are few, but include the 7400N (or 74LS00J/N/W) vs the 7400W; the 7454(J or N) compared with 7454W, 74H54, 74LS54 and 74L54W (five different 4-wide AND-OR-INVERT gate combinations of pin-out and logic function for the same device number). Ironically (given the history of competition between the two logic series), the 74HC series has grown to include pin-compatible versions of several members of the 4000 series
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, and are still in use today. They were introduced by RCA as CD4000 COS/MOS series in 1968, as a lower power and more versatile...
chips, such as the 74HC4051.
See also
- 7400 series7400 seriesThe 7400 series of transistor-transistor logic integrated circuits are historically important as the first widespread family of TTL integrated circuit logic. It was used to build the mini and mainframe computers of the 1960s and 1970s...
- List of 7400 series integrated circuits
- 4000 series4000 seriesThe 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology, and are still in use today. They were introduced by RCA as CD4000 COS/MOS series in 1968, as a lower power and more versatile...
- List of 4000 series integrated circuits
- Logic gateLogic gateA logic gate is an idealized or physical device implementing a Boolean function, that is, it performs a logical operation on one or more logic inputs and produces a single logic output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and...
- Open collectorOpen collectorAn open collector is a common type of output found 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...
- Logic familyLogic 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...
External links
- Giant Internet IC Master Database - A list of 74'xx series and other generic chip pinouts.