The 7402 DIP Quad 2-Input Logic NOR Gate is a fundamental and versatile digital IC that plays a crucial role in logic circuit design. This chip belongs to the 7400 TTL (Transistor-Transistor Logic) family and contains four independent 2-input NOR gates. Each gate performs the NOR logic operation — one of the universal logic functions — allowing you to build virtually any digital circuit, from simple logic combinations to complex sequential systems.

The 7402 IC is housed in a 14-pin Dual Inline Package (DIP-14), making it easy to use on both breadboards and printed circuit boards (PCBs). Its simple configuration, high reliability, and fast switching capability make it ideal for educational, industrial, and DIY applications.

What is a NOR Gate?

A NOR gate performs the logical operation “NOT OR.” In other words, it outputs a logic LOW (0) whenever any input is HIGH (1), and outputs a logic HIGH (1) only when all inputs are LOW (0). Because it combines the functions of both OR and NOT gates, the NOR gate is considered a universal gate — capable of implementing any other logic gate or digital function.

Technical Specifications:

IC Number: 7402
Logic Family: TTL (Transistor-Transistor Logic)
Function: Quad 2-input NOR gate
Number of Gates: 4
Inputs per Gate: 2
Package Type: DIP-14 (Dual Inline Package, 14 pins)
Operating Voltage (Vcc): 4.75V to 5.25V (Typical: 5V)
Input Voltage Range: 0V to 5V
High-Level Output Voltage (VOH): Minimum 2.4V
Low-Level Output Voltage (VOL): Maximum 0.4V
Input High Current (IIH): 40µA (max)
Input Low Current (IIL): -1.6mA (max)
Propagation Delay Time: 10–15ns (typical)
Power Dissipation: 10 mW per gate (approx.)
Operating Temperature Range: 0°C to +70°C (Commercial)
Pin Count: 14
Mounting Type: Through-hole

Pin Configuration:

1A – Input of gate 1
1B – Input of gate 1
1Y – Output of gate 1
2A – Input of gate 2
2B – Input of gate 2
2Y – Output of gate 2
GND – Ground
3Y – Output of gate 3
3A – Input of gate 3
3B – Input of gate 3
4Y – Output of gate 4
4A – Input of gate 4
4B – Input of gate 4
VCC – Supply voltage (+5V)

Key Features and Benefits:

Quad 2-Input NOR Gates:
The IC contains four independent NOR gates in one package, allowing multiple logic functions to be implemented simultaneously or combined for more complex operations.
Universal Logic Gate:
Because NOR is a universal gate, you can create any other logic gate or digital function (AND, OR, NAND, XOR, etc.) using only NOR gates, providing design flexibility.
High-Speed Operation:
Built with TTL technology, the 7402 ensures quick response times (typically around 10ns), making it suitable for high-speed logic circuits.
Standardized Voltage Compatibility:
Operates reliably at the standard 5V supply voltage, making it compatible with most digital systems and microcontroller boards like Arduino, Raspberry Pi, and ESP32 when used with proper logic level conversion.
DIP-14 Package for Easy Use:
The Dual Inline Package format makes it easy to prototype using breadboards and simplifies soldering for final circuit assembly.
Reliable and Durable:
Designed for consistent performance and long operational life, the 7402 IC provides stable logic output with strong noise immunity.

Truth Table for NOR Gate:

Input A	Input B	Output Y
0	0	1
0	1	0
1	0	0
1	1	0

From the truth table, you can see that the NOR gate outputs a HIGH only when both inputs are LOW. This fundamental behavior can be combined to build any other logic operation.

Applications:

The 7402 NOR gate IC is used in a wide variety of digital circuits and logic design projects, including:

Logic control and decision-making systems
Digital calculators and counters
Alarm and signal detection circuits
Combinational and sequential logic design
Microcontroller-based systems
Signal processing units
DIY and educational electronics projects

How It Works:

When both inputs to a NOR gate are LOW (logic 0), the output becomes HIGH (logic 1). If either or both inputs are HIGH, the output becomes LOW. Internally, the gate consists of a combination of transistors configured to perform this logical inversion of the OR operation.

For example:

Inputs (0, 0): Output = 1 (True)
Inputs (0, 1): Output = 0 (False)
Inputs (1, 0): Output = 0 (False)
Inputs (1, 1): Output = 0 (False)

This simplicity and predictability make it easy to design larger systems by combining multiple gates.

Example Use Case:

In a digital alarm circuit, the 7402 NOR IC can be used to trigger an output only when multiple input conditions are inactive, such as no motion detected and no signal received — effectively acting as a “system idle” indicator.

In microcontroller-based projects, you can use the 7402 to expand logic control or handle binary signal combinations before feeding results into the microcontroller’s input pins.

Educational Use:

The 7402 IC is a favorite in educational labs for learning digital logic theory. Students can easily build and test truth tables, understand logic behavior, and combine gates to design counters, multiplexers, or flip-flops using breadboards.

Summary:

The 7402 DIP Quad 2-Input Logic NOR Gate IC is an essential component for anyone working in electronics — from students to professional engineers. With its four high-speed NOR gates, robust TTL performance, and easy-to-use DIP package, it’s perfect for logic design, teaching, and practical circuit development.

Whether you’re constructing basic digital circuits or building complex control systems, the 7402 offers reliable, efficient, and flexible logic functionality for countless applications.

7402 NOR Gate Truth table:7402 NOR Gate Datasheet

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