7400

The 7400 is a quad 2-input NAND gate integrated circuit, part of the 7400 family of TTL logic devices. It contains four independent NAND gates, each with two inputs and one output, and is widely used as a basic building block in digital logic design.

The 7400 was introduced in the late 1960s by major semiconductor manufacturers and became a de facto standard in TTL logic. It is produced by many vendors and has spawned numerous variants in the broader 74xx family, including low-power and Schottky-transistor versions used in different performance and power scenarios.

In a typical 14-pin DIP package, the power pins are Vcc at pin 14 and GND at pin 7. The four gates are arranged so that:

- Gate 1: inputs A1 and B1, output Y1

- Gate 2: inputs A2 and B2, output Y2

- Gate 3: inputs A3 and B3, output Y3

- Gate 4: inputs A4 and B4, output Y4

The standard function of each gate is a NAND operation: the output is high unless both inputs are high. The device operates with a supply voltage around 4.75–5.25 V and provides TTL-compatible input and output levels, suitable for driving other TTL or CMOS logic inputs.

Variants in the 7400 family include devices like 74LS00 (low-power Schottky) and other speed/power grades. The 7400 remains a common reference point for teaching, prototyping, and assembling simple digital circuits due to its simplicity and reliability.