Overview
The 7400 series contains hundreds of devices that provide everything from basic logic gates, flip-flops, 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 logic in computers and industrial electronics. The original through-hole devices in dual in-line packages (DIP/DIL), which were the mainstay of the industry for many decades, are very useful for rapid breadboard-prototyping and education and so remain available from most manufacturers. The fastest types and very low voltage versions are typically surface-mount only, however.
The first part number in the series, the 7400, designates a device containing four two-input NAND gates. 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. This part was made in various packages including flat pack, plastic or ceramic dual in-line packages with 14 pins, and in surface mount packages as well. Additional numbers and letters in a full part number identify the package and other variations.
While designed as a family of digital logic, it was not unusual to see TTL chips in analog circuits like Schmitt triggers. Like the 4000 series, the newer CMOS versions of the 7400 series are also usable as analog amplifiers using negative feedback (similar to operational amplifiers with only an inverting input).
The former Soviet Union 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.
Read more about this topic: 7400 Series