Page 39 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

It has two data inputs I0 and I1, one select input S, and one output Y.

Truth table of 2 X 1 multiplexer

Boolean Equation : Y = S’I + SI 1
0

Working
• When S=0,the upper AND GATE will turn ON and lower AND GATE will turn OFF, and so the input I 0 appears
in the output.
• When S=1, the upper AND gate will turn OFF and lower AND gate will turn ON, and so the inputI1 appears in
the output.
4 X 1 Multiplexer
• It has four data inputs I3, I2, I1 and I0, two select inputs S1 & S0, and one output Y.
• Here 2 inputs, i.e. n=2 select lines and m = 1output
n=4

Truth Table

Select Line Output Y
S1 S0
0 0 0
0 1 1
1 0 12
1 1 13

Working
• According to the truth table, when S1 S0=00, the input I0 is selected and routed to the output.
• When S1 S0=01, the input I1 is selected and routed to the output.

• Similarly, when S1 S0=10, then Y=I2 & when S1 S0=11, then Y=I3.
Boolean Equation
Y = S1’S0’I0 + S1’S0I1 + S1S0’I2 + S1S0I3

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CITS : E & H - Electronics Mechanic - Lesson 9 - 29