7400 Series Guide: 74HC244/74LS244 (Octal 3-state buffer)

The 74×244 (ex 74LS244) is a cool little chip that has two 4-bit 3-state noninverting buffer/line driver.

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

What does the 74HC244 / 74LS244 do?

The 74×244 gives you two 4-bit 3-state noninverting buffer/line driver that you can use individually. A buffer is a gate that outputs the same as the input, but that gives you much more output current than a standard gate.

How To Use This Chip

The 74HC244 comes in a 20-pin package, and you need to connect it to power before you can use it. Most 7400 ICs support a VCC voltage of 5V. One difference between the HC and LS version of the chip is that the 74HC244 supports 2V to 6V, while the 74LS244 only supports 5V.

74HC chips can normally supply a maximum of 8 mA from an output pin. If you’re using the 74LS version, the maximum current you can pull out of one output pin is 15 mA when the pin is high (sourcing) or 24 mA when the pin is low (sinking).

But these values can differ between models, so check the datasheet of your model to verify.

Once you’ve connected it to power, you can use the buffer inside.

74×244 Pinout

The 74×244 has 20 pins and contains two 4-bit 3-state noninverting buffer/line driver laid out as shown in the pinout diagram below:

Pin Name	Pin #	Type	Description
1OE	1	Input	Output Enable for the first buffer group (active low).
1A1	2	Input	Input to the first buffer in the first group.
2Y4	3	Output	Output from the fourth buffer in the second group.
1A2	4	Input	Input to the second buffer in the first group.
2Y3	5	Output	Output from the third buffer in the second group.
1A3	6	Input	Input to the third buffer in the first group.
2Y2	7	Output	Output from the second buffer in the second group.
1A4	8	Input	Input to the fourth buffer in the first group.
2Y1	9	Output	Output from the first buffer in the second group.
GND	10	Power	Connect to ground (GND).
2A1	11	Input	Input to the first buffer in the second group.
1Y4	12	Output	Output from the fourth buffer in the first group.
2A2	13	Input	Input to the second buffer in the second group.
1Y3	14	Output	Output from the third buffer in the first group.
2A3	15	Input	Input to the third buffer in the second group.
1Y2	16	Output	Output from the second buffer in the first group.
2A4	17	Input	Input to the fourth buffer in the second group.
1Y1	18	Output	Output from the first buffer in the first group.
2OE	19	Input	Output Enable for the second buffer group (active low).
VCC	20	Power	Positive power supply. Connect to +5V power.

Alternatives and Equivalents for 74HC244 / 74LS244

There are many versions of the 74×244 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:

• 74HC244 (High-speed CMOS)
• 74HCT244 (High-speed CMOS, TTL compatible)
• 74LS244 (High-speed TTL)
• 74LVC244 (Low Voltage TTL)
• 74AC244 (Advanced CMOS)
• 74ALS244 (Advanced Low-Power Schottky TTL)
• 74F244 (Very High Speed)
• 74C244 (CMOS, similar to the 4000-series)

Some manufacturers also add a prefix, such as the SN74HC244 and SN74LS244 by Texas Instruments.

Can’t find the 74×244 anywhere? Then try one of the following IC alternatives:

• 74×240 – Octal buffer/driver with inverting outputs.
• 74×241 – Octal buffer/driver with tri-state outputs.
• 74×245 – Octal bus transceiver with tri-state outputs.
• CD4503 – Hex buffer with high-level output voltage capability.
• CD4509 – Hex buffer/level shifter.

If you can’t find the 74×244 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 74LS244 and 74HC244 chips

Download the PDF datasheet for your version of the 74×244 here:

• SN74HC244 (Texas Instruments)
• SN74LS244 (Texas Instruments)
• 74HC244 (Futurlec)
• 74LS244 (Futurlec)
• 74HC244 (Nexperia)