Types of Flip-Flop

Class-BCA I year 

Subject-Computer System Architecture 

Subject type-Major I 

Compiled by-Asst Professor Sulochana Patidar 

J-K Flip-Flop

Because of the invalid state corresponding to S=R=1 in the SR flip-flop, there is a need of another flip-flop. The JK flip-flop operates with only positive or negative clock transitions. The operation of the JK flip-flop is similar to the SR flip-flop. When the input J and K are different then the output Q takes the value of J at the next clock edge.

When J and K both are low then NO change occurs at the output. If both J and K are high, then at the clock edge, the output will toggle from one state to the other.

J-K Flip-Flop

Truth Table of JK Flip-Flop

J      K     Q   State

0      0     0   No Change

0      1     0   Reset

1      0     1   Set

1      1   Toggles Toggle

D Flip-Flop

In a D flip-flop, the output can only be changed at positive or negative clock transitions, and when the inputs changed at other times, the output will remain unaffected. The D flip-flops are generally used for shift-registers and counters. The change in output state of D flip-flop depends upon the active transition of clock. The output (Q) is same as input and changes only at active transition of clock.

Truth Table of D Flip-Flop

D	Q
0	0
1	1

T Flip-Flop

A T flip-flop (Toggle Flip-flop) is a simplified version of JK flip-flop. The T flop is obtained by connecting the J and K inputs together. The flip-flop has one input terminal and clock input. These flip-flops are said to be T flip-flops because of their ability to toggle the input state. Toggle flip-flops are mostly used in counters.

Truth Table of T Flip-Flop

T	Q(t)	Q(t+1)
0	0	0
0	1	1
1	0	1
1	1	0