Chapter 3_P2_MSI Lgic Circuit (Multiplexers).pdf

Digital system

1. 1
Lecture:
DIGITAL SYSTEMS
Assoc. Prof. Nguyen Thanh Hai, PhD
Chapter 5: Part 2
MSI Logic Circuits (Multiplexers)
HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering

2. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
2

3. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
3
Multiplexer has many data
inputs and one output only
Number of inputs relates to
Select input (binary code)
One Select input (0/1)
means 2
1
=2, meaning 2
data inputs (I
0, I
1), similarly
two Select inputs, meaning
4 codes corresponding to 4
data inputs, etc.0I 1I 1-N
I inputsDATA Z Output inputs
SELECT MUX
Select input is code which is used to
determine which input is transmitted
to the output Z

4. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
4
SelectOutput
S Z
0 X0
1 X110
.. XSXSz 
S
Zinputs
DATA input
SELECT
In this example, one Select
input (0/1) means 2
1
=2,
meaning 2 data inputs (X
0,
X
1),
From truth table, we can
make expression

5. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
5
A
B
D0
D1
D2
D3
Y
IC 74153
Data
inputs
Select
Inputs
Output
Select InputsOutput
B A Y
0
0
1
1
0
1
0
1
D
0
D
1
D
2
D
3
Output expression:3210
........ DABDABDABDABY 
Similarly, easy to find the expression, as well as design this
circuit using logic gates.

6. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
6
D
0
D
1
D
2
D
3
Y3210
........ DABDABDABDABY 
Select InputsOutput
B A Y
0
0
1
1
0
1
0
1
D
0
D
1
D
2
D
3
The logic circuit with 2 Select inputs of code and 4 data inputs

7. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
7
IC 74151
A
B
C
D0
D1
D2
D3
Y
8-inputs
data
3-inputs
select
outputs
D4
D5
D6
D7Y
Enable G
EnableSelect inputsOutput
G C B AY
0
0
0
0
0
0
0
0
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
D0
D1
D2
D3
D4
D5
D6
D77654
3210
................
...............
DABCGDABCGDABCGDABCG
DABCGDABCGDABCGDABCGY


Using IC 74151, 3 Select inputs (2
3
=8 state), each state is for
one input connected to the output Y.

8. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
8
Logic circuit of IC74151 with 8 input, 3 Select inputs and one
output ( Multiplexers)

9. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
9
Input Output
F
C B A Y
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
D0
D1
D2
D3
D0
D1
D2
D3
1
0
0
0
1
1
1
0
CBA
F )6,5,4,0(
Multiplexer of IC 74153 has 2 Select inputs for 4 inputs to select one
input corresponding to one code to connect to output Y
D
0=V
cc=+5V (Level 1), D
3=0, D
1=D
2=C (X=1/0) is considered the 3
rd
input as shown in Table
A
B
D0
D1
D2
D3
Y
IC 74153
A
B
+Vcc
C
F

10. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
10
74HC151
Multiplexer of IC 74151 has 3 Select inputs for 8 inputs to select one
input corresponding to one code to connect to output Y
G is active Low, used for increasing capacity of multiplexer inputs from 8
inputs into 16 inputs.

11. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
11
Datasheet
Example: increase the input capacity

12. HCMC University of Technology and Education
Faculty of Electrical & Electronic Engineering Multiplexers (Data Selectors)
Assoc. Prof. Nguyen ThanhHai, PhD
12
The End