in these slides the concepts of flip flop and latches have been explained with the add of animations and from the very basics so that it become user easy to understand this concepts easily.

1. LATCHES & FLIPFLOPS
UNIT-2
Mohammad Asif Iqbal
Assistant Professor,
Deptt of ECE,
JETGI, Barabanki

2. STORAGE ELEMENTS

3. BEFORE STARTING LET’S RECALL NAND GATE
A B Y
0 0 1
0 1 1
1 0 1
1 1 0

4. BASIC STORAGE ELEMENT
0
1
1
0
1
LATCH

5. FLIP-FLOP
CLOCK
S
R
Q
Q’
=1
=0
0
1
=1
=0
0
0
1
0
0 0 1 0

6. FLIP-FLOP
CLOCK
S
R
Q
Q’
=0
=1
1
0
=0
=1
0
0
0
1
0 0 1 0
0 1 0 1
0 0 0 1

7. FLIP-FLOP
INPUT OUTPUT
S R Q Q’
0 0 NO CHANGE
0 1 0 1
1 0 1 0
1 1 ? ?
S
R
CLOCK
Q’
Q SET
RSET
=1
=1
0
0
=1
=1
INDETERMINANT
CHARACTERISTIC
TABLE

8. BLOCK DIAGRAM REPRESENTATION
S
R
Q’
Q
CLOCK
D
D Q Q’
0 0 1
1 1 0
Q Q(n+1) D
0 0 1
1 1 0
Q(n) D Q(n+!)
0 0 1
1 1 0

9. D FLIP-FLOP
D Q Q’
0 0 1
1 1 0
Q Q(n+1) D
0 0 1
1 1 0
Q(n) D Q(n+!)
0 0 1
1 1 0
CHARACTERIS
TIC TABLE
TRUTH TABLE
EXCITATION
TABLE

10. J K FLIP-FLOP
J
K
CLOCK
Q
Q’
=1
=0
1
0
=1
=1
=1
=0=0
=1 =0
=1

11. WAVE FORM REPRESENTATION
(t)
T 2T
CLOCK
Q
0
1
NOW, changes at I/P
will affect O/PAny change at I/P
will not effect O/P
0
1
RACE
AROUND
CONDITION

12. SOLUTION OF RACE AROUND CONDITION
(t)
T 2T
CLOCK
Q
0
1
0
1
T F
PROPAGATION DELAY

13. FINAL SOLUTION……
(t)
T 2T
CLOCK
Q
0
1
0
1

14. PROBLEMS
Q:- Determine the output of PGT
clocked SR flip flop which Q
initially 0 for the given input
waveforms
Q
Q’
Q:- Determine the output of PGT
clocked SR flip flop which Q
initially 1 for the given input
waveforms.

15. Master Slave Flip Flop
K
J
Q
Q’=0
=1
0 0 1 1
=1
=1
1
0
=1
=0 =1
=0=0
=1

16. THANK YOU!