### Multiplexers

A multiplexer is a circuit which has many inputs but only one output. Multiplexer or MUX means many into one. By applying proper control signal we can steer any input to the output. Therefor it is also known as data selector and control inputs are called select inputs.

**Watch this ppt on Multiplexer**

MUXBlockDia gives the general idea of MUX. m control signal can select maximum 2 rest to m input signals and therefore n should be less than or equal to 2 rest to m.

Click on this Image for Multiplexer Animation

As shown in the circuit diagram ‘**a**‘ (or A) and ‘**b** ‘(or B) are control inputs, A (or D0),B(or D1),C(or D2).D(or D3) are data inputs and Q (or Y) is output.

First end gate will give output of** a’b’**A(0r A’B’D0), second **a’b**B(or A’BD1), third **ab’**C(or AB’D2) and fourth **ab**D(or ABD3) and these output will be given to ‘OR’ which will give output as

Q=**a’b’**A+**a’b**B+**ab‘**C+**ab**D

or

Y=A’B’D0+A’BD1+AB’D2+ABD3

From above equation, suppose control inputs **a** (or A) =0 and **b **(or B)=0 then

Q=0’0’A+0’0B+00’C+00D

or

Y=0’0’D0+0’0D1+00’D2+00D3

Therefore Q or Y =1.1D0+1.0D1+0.1D2+0.0D3

Q or Y =D0

Similarly, for control inputs **ab or AB =00 the first AND gate to which D0 or A is connected will activate and its output is D0 and all other AND gates are inactive with zero output. Thus Q or Y output with ab or AB=00 will be D0. If D0=0 then output will be zero and if Do=1 output will be 1.**

Same way, for **ab or AB =01, the Q or Y output will be D1. In a similar manner we get the following truth table**

Control Inputa or A b or B | OutputQ or Y |

0 0 | Do or A |

0 1 | D1 or B |

1 0 | D2 or C |

1 1 | D3 or D |

**More clearly go through this ppt **

- Watch video on Multiplexer Based Design.

Combinational Logic-Multiplexer

Summary: Must go through this page of MUX

**Assignment:
**

**Q.1 How many control inputs are required for 5-to-1 MUX?**

**Q.2. Give the type of commercial ICs of multiplexer.**

**Q.3 Send link of 16-to-1 multiplexer with its output Y equation **

**and explain its operation in brief.**

**Q.4 Draw the pinout diagram of 74150 of multiplexer IC and **

**describe its function with truth table?**

**Q.5 Can we design multiplexer using OR gates in place of AND and AND gate in place of OR?
**

**Q.5 Go to this link of Multiplexer Applet(on right top and click on multiplexer) and explain the operation of MUX circuit with its truth table in excel sheet?**

**Q.6 Go to this Learning Object of Multiplexer and answer the four questions given in it.**

**Q.7 Search the link of MUX tutorial(at least 5 other than used already) and its ICs relevant to our syllabus.**

**Q.8 Search the ppts and pdf of MUX other than used here.**

**Q.9 Give links of MUX video and audio relevant to our syllabus.
**