74266 IC – Quad 2-Input Exclusive-NOR (XNOR) Logic Gate IC, Open-Collector Output

The 74266 IC is a digital logic IC containing four independent 2-input Exclusive-NOR (XNOR) gates. It is commonly used in digital logic circuits where two input signals need to be compared and the output must become active when both inputs are in the same logic state.

An XNOR gate produces a logic HIGH condition when its two inputs are equal, making the 74266 useful for digital comparison, equality detection, parity checking, control logic, binary matching and educational electronics experiments.

The 74266 belongs to the 74-series TTL logic family and is typically supplied in a 14-pin DIP package, making it suitable for breadboards, IC sockets and through-hole PCB designs.

A key feature of the 74266 is its open-collector output configuration. Because of this, an external pull-up resistor is normally required at the output for proper logic operation. Open-collector outputs also make the IC useful in certain wired-logic and interface applications.

It is suitable for students, hobbyists, technicians and electronics developers working with digital logic projects, truth-table experiments, comparator circuits, TTL circuits and embedded electronics interfaces.

Key Features

• Quad 2-input XNOR logic gates
• Four independent logic gates in one IC
• Equality/comparison logic operation
• Open-collector outputs
• TTL 74-series logic family
• Typically operates from a 5V supply
• 14-pin DIP package
• Suitable for breadboards and PCBs
• Useful for digital logic and educational projects
• Supports parity and binary comparison applications

Important: The 74266 is an XNOR (Exclusive-NOR) IC, not a standard XOR IC. If you require XOR operation, ICs such as 7486 / 74LS86 are commonly used.

Specifications

Note: Exact electrical parameters can vary depending on manufacturer and specific suffix such as 74266, 74LS266 or equivalent. Refer to the exact IC marking and datasheet before using it in critical applications.