Chapter 5 – Sequential Circuits

S-R Flip-Flop Descriptors
• Characteristic Table
S
0
0
1
1
R
0
1
0
1
Q(t+1)
Q(t)
0
1
?
Operation
No change
Reset
Set
Undefined
• Characteristic Equation
Q(t+1) = S + R Q, S . R = 0
• Excitation Table
Q(t)
Q(t+1) S R
Operation
0
0
1
0
1
0
0
1
0
X
0
1
No change
Set
Reset
1
1
X
0
No change
Chapter 5 - Part 2 47
J-K Flip-Flop Descriptors
• Characteristic Table
0
0
1
1
• Characteristic Equation
Q(t+1) = J Q + K Q
• Excitation Table
J
K
0
1
0
1
Q(t)
Q(t+1)
Q(t)
0
1
Q(t)
Q(t+ 1) J K
Operation
No change
Reset
Set
Complement
Operation
0
0
1
1
0
1
0
1
0
1
X
X
X
X
1
0
No change
Set
Reset
No Change
Chapter 5 - Part 2 48
24