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.

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:

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.

74HC7266 Pinout

Pin #	Type	Description
1	Input	Input to the first XNOR gate.
2	Input	Input to the first XNOR gate.
3	Output	Output from the first XNOR gate.
4	Output	Output from the second XNOR gate.
5	Input	Input to the second XNOR gate.
6	Input	Input to the second XNOR gate.
7	Power	Connect to ground (GND).
8	Input	Input to the third XNOR gate.
9	Input	Input to the third XNOR gate.
10	Output	Output from the third XNOR gate.
11	Output	Output from the fourth XNOR gate.
12	Input	Input to the fourth XNOR gate.
13	Input	Input to the fourth XNOR gate.
14	Power	Positive power supply (VCC). Connect to +5V power.

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.

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:

• CD74HC7266 (Texas Instruments)
• 74HC7266 (Phillips Semiconductors)