# Demultiplexer in Digital Electronics

In this lecture, we are going to cover another combinational circuit called Demultiplexer in Digital Electronics. We will cover what a is Demultiplexer, the block diagram of the Demultiplexer, the types of Demultiplexer, the need for Demultiplexer, and the advantages of Demultiplexer and in the end, we will see the application of Demultiplexer.

Also Read: Multiplexer in Digital Electronics

## What is Demultiplexer

The block diagram of Demultiplexer is shown in the below figure. It has only one input, n0outputs, and m-select inputs.

A demultiplexer performs the reverse operation of a multiplexer i.e. it receives one input and distributes it over several outputs.

At a time only one output line is selected by the select lines and the input is transmitted to the selected output line.

Hence a demultiplexer is equivalent to a single pole multiple-way switch.

The enabled input will enable the demultiplexer. The relation between the n output lines and m select lines is as follows:

n = 2^m

## Types Of Demultiplexer

Sure! Here is a table showcasing the different types of demultiplexers:

Each demultiplexer type allows you to select one of the output lines based on the combination of input values for the given number of input lines and select inputs.

So, now we are going to learn about each type of demultiplexer in detail.

## 1 To 2 Demultiplexer

• The block diagram of 1 to 2 demultiplexer is shown in the figure below. It has one data input Din, one select input S0, one enable (E) input, and two outputs Y0 and Y1.

### 1 to 2 Demultiplexer Truth Table

• The 1 to 2 demultiplexer truth table is shown in the below figure.
• If E = 0 then both the outputs will be 0 irrespective of the inputs.

### Realization of 1 to 2 Demultiplexer

• Step 1: To realize the 1 to 2 demultiplexer using the gates, we have to write the truth table as given in the below image.
• Step 2: Write the K-map.

Thus the expressions for Y0 and Y1 are as follows:

\mathbf{Y_0 = ED_{in}\bar S_0} and \mathbf{Y_1 = ED_{in} S_0}

## 1 To 4 Demultiplexer

• The block diagram of 1 to 4 demultiplexer is shown in the figure below.
• Din is connected to Y0 when S1S0 = 00, it is connected to Y1 when S1S0 = 01, and so on. The other outputs will remain zero.
• The enable inputs need to be high in order to enable the demux. If E = 0 then all the outputs will be low irrespective of everything.

### 1 to 4 Demultiplexer Truth Table

• The 1 to 4 demultiplexer truth table is shown in the below figure.

### 1 to 4 Demultiplexer K-map

• The K-maps for the four outputs are shown in the figure below.

### 1 to 4 Demultiplexer Circuit Diagram

• The 1 to 4 Demultiplexer Circuit Diagram is shown in the below figure.

## 1 to 8 Demultiplexer

• The block diagram of 1 to 8 demultiplexer is shown in the figure below.
• It has one data input, eight outputs, three select inputs, and an enable input E.
• Depending on the combination of the select inputs S2 S1 S0, the data input Din is connected to one of the eight outputs.
• For example if S2 S1 S0 = 1 1 0 then Din is connected to Y6.

### 1 to 8 Demultiplexer Truth Table

• The 1 to 8 Demultiplexer Truth Table is shown in the below figure.

### 1 to 8 Demultiplexer Circuit Diagram

• The 1 to 8 Demultiplexer Circuit Diagram is shown in the below figure.

## Application of Demultiplexer

Demultiplexers, often abbreviated as “demux,” have various practical applications in electronics and digital systems. Their primary function is to take a single input signal and distribute it to one of several output lines based on a control signal. Here are some common application of demultiplexer:

1. Data routing within digital systems
2. Display multiplexing in LED or LCD displays
3. Address decoding in microprocessor systems
5. Separating channels in communication systems
6. LED matrix scanning for displays
7. Controlling print head elements in printers
8. Routing signals in programmable logic devices (PLDs) and FPGAs
9. Instrumentation and test equipment for signal distribution
10. Channel selection in digital signal processing (DSP) applications

## FAQs on Demultiplexer

### What is demultiplexer and application of demultiplexer?

Demultiplexer is used to connect a single source to multiple destinations. The main application area of demultiplexer is the communication system, where multiplexers are used. Most of the communication systems are bidirectional i.e., they function in both ways (transmitting and receiving signals).

### What are the types of demultiplexers?

The different types of demultiplexers are 1:2 Demux, 1:4 Demux, 1:8 Demux, 1:16 Demux, 1:32 Demux.

### why is a demultiplexer called a data distributor?

A demultiplexer sends a single input to multiple outputs, depending on the select lines. For one input, the demultiplexer gives several outputs. That is why it is called a data distributor.

### What are the components of a demultiplexer?

Demultiplexer consists of 1 input line, ‘n’ output lines, and ‘m’ select lines.

### What is the IC number of the demultiplexer?

These are available in different IC packages and some of the most commonly used demultiplexer ICs include 74139 (dual 1:4 DEMUX), 74138 (1:8 DEMUX), 74237 (1:8 DEMUX with Address Latches), 74154 (1:16 DEMUX), 74159 (1:16 DEMUX open collector type), etc. NOTE: The Demultiplexer ICs are also called Decoder ICs.  Join Our Telegram Group!