Encoders PPT ... You can watch my lectures at: Digital electronics playlist in my youtube channel: https://www.youtube.com/channel/UC_fItK7wBO6zdWHVPIYV8dQ?view_as=subscriber My Website : https://easyninspire.blogspot.com/

2. Today's Topic
Combinational Logic Circuits
• Encoders

3. Encoder
• In general an Encoder is a device or crkt. that converts data from one
format to another.
• In Digital circuits Encoder is a combinational circuit that is used to
represent N bit code for the input data.
• It has maximum of n input lines and ‘n’ output lines
2
n
• Eg: if n=n= then encoder is having 2 i/p lines and o/p lines
Similarly if n=n= then encoder is having 3 i/p lines and o/p lines
if n=n= then encoder is having 4 i/p lines and o/p lines

4. to Encoder
• We know that if n= then encoder is having 2 i/p lines and o/p
lines that means it is a to Encoder
• Let Encoder has four inputs D3, D2 D1 & D0 and two outputs
A1 & A0.
• The block diagram is D3
D2
D1
D0
Truth Table is
D3 D0D1D2
D0
Boolean Exp:
1 3 2
0 3 1

5. Boolean Exp:
1 3 2
0 3 1
D3
D2
D1

6. to Encoder/ Octal to Binary Encoder
• 7 0
2 1 0
•
D7
D6
D5
D4D4
D3
D2
D1
D0

7. Truth Table:
D7 D6 D5 D4 D3 D2 D1 D0
Boolean Expressions
A2=D7+D6+D5+D4
A1=D7+D6+D3+D2
A0=D7+D5+D3+D1

8. •
A2=D7+D6+D5+D4
A1=D7+D6+D3+D2
A0=D7+D5+D3+D1
D7
D6
D5
D4
D3
D2
D1

9. Drawbacks of Encoder
•
•
3 6
3
3 6
3
6.
•

10. •
•
•
• Let Encoder has four inputs D3, D2 D1 & D0 and two outputs
A1 & A0.
3 2 1 0
1 0
• 3
0

11. A1 A0
• 3 3
• 0

12. •
For A1
For A0
A1 = D2 + D3 A0 =D1 D2’ + D3

13. 3
2
1
A1 = D2 + D3
A0 =D1 D2’ + D3
1
D0
A0 =D1 D2’ + D3
V=D3+D2+D1+D0

14. In Next Class
• Decoders

15. • A