7400 Series Guide: 74HC7266 (XNOR gates)

The 74HC7266 is a chip with four basic XNOR gates inside. An XNOR gate is a logic gate – one of the most basic building blocks in digital electronics.

In this guide, you will learn everything you need to know about this chip and how you can use its XNOR gates in your own projects.

Chip package and pinout for the 74HC7266
74HC7266 chip and pinout

What does the 74HC7266 do?

The 74HC7266 gives you four basic XNOR gates that can be used individually. An XNOR gate is a logic gate that outputs 1 (HIGH) if its inputs are equal (both 1 or both 0). In the truth table below, you can see what the output will be for any given input:

XNOR gate truth table
Truth table for the XNOR gate

How To Use This Chip

The 74HC7266 comes in a 14-pin package, and you need to connect it to power before you can use it. The chip supports a supply voltage of between 2V and 6V. Each gate output of the 74HC7266 can sink or source 4 mA when powered with 5V.

Once it’s connected, you can use any of the four basic XNOR gates inside.

7400 series IC connected to 5V on a breadboard
The 74HC7266/74LS7266 IC connected to power

74HC7266 Pinout

Pinout for the 74HC7266 chip
Pin #TypeDescription
1InputInput to the first XNOR gate.
2InputInput to the first XNOR gate.
3OutputOutput from the first XNOR gate.
4InputInput to the second XNOR gate.
5InputInput to the second XNOR gate.
6OutputOutput from the second XNOR gate.
7PowerConnect to ground (GND).
8OutputOutput from the third XNOR gate.
9InputInput to the third XNOR gate.
10InputInput to the third XNOR gate.
11OutputOutput from the fourth XNOR gate.
12InputInput to the fourth XNOR gate.
13InputInput to the fourth XNOR gate.
14PowerPositive power supply (VCC). Connect to +5V power.
Pin overview for the 74×7266 IC

XNOR Circuit Example: Edge Detection

Here’s a simple project you can build with the XNOR gates in the 74HC7266 IC: Edge detection circuit.

This circuit detects a signal going from low to high, or from high to low, and converts it to a pulse that keeps the LED on for a short while. No matter if the input pulse is long or short, the LED will stay on for the same amount of time.

Edge detection circuit using an XNOR gate

To build this circuit, you’ll need the following parts:

  • 74HC7266 (Or other IC with XNOR gates)
  • LED (L1)
  • 100 kΩ resistor (R1)
  • 1 kΩ resistor (R2)
  • 100 µF Capacitor (C1)

Alternatives and Equivalents

If you can’t find the 74HC7266 IC in your local electronics store, don’t worry, you’ll most likely find it in one of the stores listed on this page of online stores where you’ll find components and tools for all your electronics projects.

Can’t find it anywhere? Then try one of the following IC alternatives:

  • 74×266 – Quad 2-input XNOR gates (with open-collector outputs).
  • 74×810/74×811 – Quad 2-input XNOR gates.
  • CD4077 – Quad 2-input XNOR gates.

Datasheet For the 74HC7266 Chip

Download the PDF datasheet for your version of the 74HC7266 here:

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