Flip - Flops

Flip - Flops

  • Flip - Flops are sequential digital circuits that are synchronous bistable devices and can store stable states(1 , 0) of information. They are also known as bistable multivibrators. Output of the flip-flop changes only when a certain point (either the rising or falling edge) on the triggering input called Clock(CLK).
  • An edge-triggered flip-flop only changes its state when the clock pulse shifts from low to high – rising edge(positive edge) or high to low-falling edge (negative edge), and it only responds to its inputs during these clock transitions.
  • There is a difference in the logic symbols for positive edge-triggered and negative edge-triggered flip-flops.The negative edge-triggered flip-flop symbol is similar to the positive edge one  but with an inversion bubble or small circle added to the clock input line, indicating that the flip-flop responds to the falling edge (negative edge) of the clock signal.
  • Here is an example of the logic symbol for a D flip-flop.


There is a key difference between a latch and a flip-flop.

  • A latch is level-triggered, meaning its output changes instantly whenever its input changes.
  • A flip-flop is edge-triggered, which means it changes its output only when a specific edge (transition from low to high or high to low) is detected on its clock signal.


Difference between Latch and the Flip Flop.

Latch Flip Flop
A Latch is a level-triggered device. A Flip Flop is an edge-triggered device.
Response to input signal changes immediately. Response to changes on clock signal edge.
Clock signal is not required. Clock signal is required.
Latches are simpler design. Flip flops are more complex design.
Latches are faster. Flip flops are slower.

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