7400 Series Guide: 74HC05/74LS05 (Hex open-collector inverters)

The 74×05 (also known as 74HC05) is a chip with six open-collector inverters – or NOT-gates. An open collector output means you can hook it up to different logic levels easily. But, it also means the outputs behave a little bit differently from a standard NOT gate chip.

In this guide, you’ll learn what this chip does and how you can use NOT gates for whatever it is you’re making.

Chip package and pinout for the 74HC05/74LS05
74HC05 chip and pinout

What does the 74HC05 / 74LS05 do?

The 74×05 gives you six NOT gates. Each with an open-collector output. A NOT gate (or inverter) is a logic gate that outputs the opposite of the input. In the truth table below, you can see what the output will be for any given input:

NOT gate truth table
Truth table for the NOT gate (inverter)

How To Use This Chip

The 74HC05 comes in a 14-pin package.

First, you need to connect it to power. Then you can use any of the gates inside it. Most 7400 ICs support a VCC voltage of 5V. One difference to make note of between the HC and LS versions is that 74HC05 supports 2V to 6V, while the 74LS05 only supports 5V.

7400 series IC connected to 5V on a breadboard

Once you’ve connected the power, you can use any of the six open-collector inverters inside.

Keep in mind that this chip has open-collector outputs which means you can only sink current, not source it.

The output of each gate in the 74HC03 can sink around 4 milliamps when it’s powered with 5 volts. On the other hand, the 74LS03 can usually handle about 8 milliamps of current. But, these values might differ depending on the chip manufacturer.

74×05 Pinout

The 74×05 has 14 pins and has six inverters laid out as shown in the pinout diagram below:

Pinout for the 74HC05/74LS05 chip
Pin #TypeDescription
1InputInput to the first NOT gate.
2OutputOpen-collector output from the first NOT gate.
3InputInput to the second NOT gate.
4OutputOpen-collector output from the second NOT gate.
5InputInput to the third NOT gate.
6OutputOpen-collector output from the third NOT gate.
7PowerConnect to ground (GND).
8OutputOpen-collector output from the fourth NOT gate.
9InputInput to the fourth NOT gate.
10OutputOpen-collector output from the fifth NOT gate.
11InputInput to the fifth NOT gate.
12OutputOpen-collector output from the sixth NOT gate.
13InputInput to the sixth NOT gate.
14PowerPositive power supply (VCC). Connect to +5V power.
Pin overview for the 74×05 IC

Alternatives and Equivalents for 74HC05 / 74LS05

There are many versions of the 74×05 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:

  • 74HC05 (High-speed CMOS)
  • 74HCT05 (High-speed CMOS, TTL compatible)
  • 74LS05 (High-speed TTL)
  • 74LVC05 (Low Voltage TTL)
  • 74AC05 (Advanced CMOS)
  • 74ALS05 (Advanced Low-Power Schottky TTL)
  • 74F05 (Very High Speed)
  • 74C05 (CMOS, similar to the 4000-series)

Some manufacturers also add a prefix, such as the SN74HC05 and SN74LS05 by Texas Instruments.

Can’t find the 74×05 anywhere? Then try one of the following IC alternatives:

  • 74×04 – Hex inverters.
  • 74×14 – Hex inverters (with Schmitt-trigger inputs).
  • CD4049 – Hex inverting buffers/converter.
  • CD4069 – Hex inverters/NOT-gates.
  • CD40106 – Hex inverters (with Schmitt-trigger inputs).

If you can’t find the 74×05 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 74LS05 and 74HC05 chips

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