7400 Series Guide: 74HC12/74LS12 (3-input NAND gates)

The 74×12 (ex 74LS12) is a chip with three 3-input open-collector NAND gates. With an open collector output, it’s easy to connect it to other chips that use different logic levels. However, it also means you can’t just swap it out with a regular NAND gate chip

In this guide, you’ll learn the things you need to know about this chip to use 3-input NAND gates in your own projects.

What does the 74HC12 / 74LS12 do?

The 74×12 gives you three 3-input open-collector NAND gates. A NAND gate is a logic gate that outputs 0 (LOW) only if all of its inputs are 1 (HIGH).

Input A	Input B	Input C	Output Q
0	0	0	1
0	0	1	1
0	1	0	1
0	1	1	1
1	0	0	1
1	0	1	1
1	1	0	1
1	1	1	0

How To Use This Chip

The 74LS12 comes in a 14-pin package, and you need to connect 5V to its power pins before you can use it.

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

The output of each gate in the 7412 can sink around 16 milliamps. On the other hand, the 74LS12 can usually handle about 8 milliamps of current. However, these values might differ depending on the chip manufacturer.

74×12 Pinout

The 74×12 has 14 pins and contains three 3-input open-collector NAND gates laid out as shown in the pinout diagram below:

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

Alternatives and Equivalents for 74HC12 / 74LS12

There are many versions of the 74×12 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:

• 7412
• 74HC12 (High-speed CMOS)
• 74HCT12 (High-speed CMOS, TTL compatible)
• 74LS12 (High-speed TTL)
• 74LVC12 (Low Voltage TTL)
• 74AC12 (Advanced CMOS)
• 74ALS12 (Advanced Low-Power Schottky TTL)
• 74F12 (Very High Speed)
• 74C12 (CMOS, similar to the 4000-series)

Some manufacturers also add a prefix, such as the NTE7412 by NTE Electronics.

Can’t find the 74×12 anywhere? Then try one of the following IC alternatives:

• 74×10 – Triple 3-input open-collector NAND gates
• CD4023 – Triple 3-input NAND gates

If you can’t find the 74×12 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 74×12 chip

Download the PDF datasheet for your version of the 74×12 here:

• 74LS12 (National Semiconductor)
• 7412 (NTE Electronics)