7400 Series Guide: 74LS26 (open-collector NAND gates)

The 74×26 (ex 74LS26) is a chip that comes packed with four open-collector NAND gates. An open collector output makes it easy to interface with chips of different logic levels. But it also means you use it as a direct replacement for a standard NAND gate chip.

Learn how it works and how to use it with this beginner-friendly guide and start using open-collector NAND gates in your projects.

74HC26 / 74LS26 Package And Pinout

What does the 74LS26 do?

The 74×26 gives you four open-collector NAND gates. Each output supports a voltage of up to 15V. A NAND gate is a logic gate that outputs 0 (LOW) only if all of its inputs are 1 (HIGH). In the truth table below, you can see what the output will be for any given input:

NAND gate truth table
Truth table for the NAND gate

How To Use This Chip

The 74LS26 comes in a 14-pin package, and you need to connect its power pins before you can use it. Like most 7400 ICs, it supports a VCC voltage of 5V.

This chip uses open-collector outputs which means you can only sink current, not source it.

Open-collector NAND gate

The 74LS26 can usually sink about 8 to 16 milliamps of current. But, these values might differ depending on the chip manufacturer.

7400 series IC connected to 5V on a breadboard
The 74HC26/74LS26 IC connected to power

74LS26 Pinout

The 74×26 has 14 pins and contains four open-collector NAND gates laid out as shown in the pinout diagram below:

74LS26 Pinout
Pin #TypeDescription
1InputInput to the first NAND gate.
2InputInput to the first NAND gate.
3OutputOpen-collector output from the first NAND gate.
4InputInput to the second NAND gate.
5InputInput to the second NAND gate.
6OutputOpen-collector output from the second NAND gate.
7PowerConnect to ground (GND).
8OutputOpen-collector output from the third NAND gate.
9InputInput to the third NAND gate.
10InputInput to the third NAND gate.
11OutputOpen-collector output from the fourth NAND gate.
12InputInput to the fourth NAND gate.
13InputInput to the fourth NAND gate.
14PowerPositive power supply (VCC). Connect to +5V power.
Pin overview for the 74×26 IC

Alternatives and Equivalents for 74×26

There are many versions of the 74×26 chip. They all have the same functionality, but with different specifications such as supported voltages and maximum current output.

Here’s a list of a few equivalents of this chip:

  • 74HC26 (High-speed CMOS)
  • 74HCT26 (High-speed CMOS, TTL compatible)
  • 74LS26 (High-speed TTL)
  • 74LVC26 (Low Voltage TTL)
  • 74AC26 (Advanced CMOS)
  • 74ALS26 (Advanced Low-Power Schottky TTL)
  • 74F26 (Very High Speed)
  • 74C26 (CMOS, similar to the 4000-series)

Some manufacturers also add a prefix, such as the SN74HC26 and SN74LS26 by Texas Instruments.

Can’t find the 74LS26 anywhere? Then try one of the following IC alternatives:

  • 74×01 – Quad 2-input open-collector NAND gates.
  • 74×03 – Quad 2-input open-collector NAND gates.

If you can’t find the 74LS26 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.

Datasheet for the 74LS26 chip

Download the PDF datasheet for your version of the 74×26 here:

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