Multiplexer :-
It is known as MUX..
Multiplexing is the process of connecting many inputs to one output it is "many into one " process with appropriate logic control signals.
Multiplexer is a basic block or basic logic combinational circuit with
i) 'n' input lines
ii) 'm' control lines / selector lines
iii) one output line 'Y'
It requires OR gate in the O/P.
It cannot be used as a decoder.
Example :- IC 74153,74157
To calculate Select line - Formula :- 2
m = n
where, n is the input lines
m is the control lines
4:1 Multiplexer :
Truth table :-
| S1 | S0 | Y = |
| 0 | 0 | D0 |
| 0 | 1 | D1 |
| 1 | 0 | D2 |
| 1 | 1 | D3 |
It has 4 input lines (D0 ,D1,D2,D3) two control lines (S1 S0) called select lines and one output line by 'Y'
Working:-
1) When the control word is S1 and S0 is 0 0 then Y = D0
2) When the control word is S1 and S0 is 0 1 then Y = D1
3) When the control word is S1 and S0 is 1 0 then Y = D2
4) When the control word is S1 and S0 is 1 1 then Y = D3
Note that at any instant only one AND is enabled allowing only one data line transmission to the common output line.
