7400 Series Guide: 74HC151/74LS151 (8-to-1 multiplexer)

The 74×151 (ex 74HC151) is a chip that features an 8-to-1 multiplexer, allowing it to select one of eight data inputs and direct it to a single output line.

In this guide, you’ll learn the things you need to know about this chip in order to use multiplexers effectively in your own projects.

What does the 74HC151 / 74LS151 do?

The 74×151 is an 8-to-1 multiplexer. This means it can select one of the eight input signals (D0 to D7) and pass it to a single output (Y) based on control inputs.

It uses three select inputs (S0, S1, S2) to determine which one of the eight data inputs will be connected to the output. In addition to these inputs, there is an active-low enable input (E). To get a meaningful output, the enable input should be LOW.

This chip is useful in digital circuits for selecting data from multiple sources, like data routing and resource sharing in systems.

How To Use This Chip

The 74HC151 comes in a 16-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 74HC151 supports 2V to 6V, while the 74LS151 only supports 5V.

74HC chips can normally supply a maximum of 4 mA from an output pin. If you’re using the 74LS version, the maximum current you can pull out of one output pin is 0.4 mA when the pin is high (sourcing) or 8 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 8-to-1 multiplexer inside.

74×151 Pinout

The 74×151 has 16 pins and contains 8-input multiplexer with common select inputs and enable input laid out as shown in the pinout diagram below:

Pin Name	Pin #	Type	Description
I3	1	Input	Data input 3 for the 8-to-1 multiplexer.
I2	2	Input	Data input 2 for the 8-to-1 multiplexer.
I1	3	Input	Data input 1 for the 8-to-1 multiplexer.
I0	4	Input	Data input 0 for the 8-to-1 multiplexer.
Y	5	Output	Output from the 8-to-1 multiplexer.
W	6	Output	Complemented output from the multiplexer.
I4	7	Input	Data input 4 for the 8-to-1 multiplexer.
GND	8	Power	Connect to ground (GND).
I5	9	Input	Data input 5 for the 8-to-1 multiplexer.
I6	10	Input	Data input 6 for the 8-to-1 multiplexer.
I7	11	Input	Data input 7 for the 8-to-1 multiplexer.
G	12	Input	Enable input (active low).
B	13	Input	Select input B for the multiplexer.
A	14	Input	Select input A for the multiplexer.
C	15	Input	Select input C for the multiplexer.
VCC	16	Power	Positive power supply. Connect to +5V power.

Alternatives and Equivalents for 74HC151 / 74LS151

There are many versions of the 74×151 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:

• 74HC151 (High-speed CMOS)
• 74HCT151 (High-speed CMOS, TTL compatible)
• 74LS151 (High-speed TTL)
• 74LVC151 (Low Voltage TTL)
• 74AC151 (Advanced CMOS)
• 74ALS151 (Advanced Low-Power Schottky TTL)
• 74F151 (Very High Speed)
• 74C151 (CMOS, similar to the 4000-series)

Some manufacturers also add a prefix, such as the SN74HC151 and SN74LS151 by Texas Instruments.

Can’t find the 74×151 anywhere? Then try one of the following IC alternatives:

• 74×150 – 16-to-1 multiplexer.
• 74×153 – Dual 4-to-1 multiplexer.
• 74×251 – 8-to-1 multiplexer with 3-state outputs.
• CD4051 – 8-channel analog multiplexer/demultiplexer.
• CD4052 – Dual 4-channel analog multiplexer/demultiplexer.
• CD4053 – Triple 2-channel analog multiplexer/demultiplexer.

If you can’t find the 74×151 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 74LS151 and 74HC151 chips

Download the PDF datasheet for your version of the 74×151 here:

• SN74HC151 (Texas Instruments)
• SN74LS151 (Texas Instruments)
• 74HC151 (Futurlec)
• 74LS151 (Futurlec)
• 74HC151 (Nexperia)