Flip Flop Tutorial

Digital Electronics: Flip-flop tutorial

This here will be a quick tutorial on flip-flops. We’ll look at the different types and some of their applications. But first, what is a flip-flop?

A flip-flop is a digital electronic device that has two possible states, on or off (1 or 0). It stays in its state and outputs its value until something on its inputs cause it to change the state. The type of input signal(s) that does this depends on the type of flip-flop. Certain flip-flops could also be called latches.

SR Schematic
SR Schematic

Types of Flip-flops

SR-type flip-flop/latch
The SR-type flip-flop has two inputs and one or two outputs. The S and R inputs sets and resets the latch respectively. The current state is output on Q. Some (if not all O_o) flip-flop ICs also have a ¬Q output which is merely the inverse of the current state.

D-type flip-flop
The D-type flip-flop generally has two inputs: a Data and a Clock input. The outputs are Q, and ¬Q, the current state and the inverse of the state. This flip-flop will only change its state when the Clock input transitions to high; its state will become whatever the input D is. When the Clock input is low, no change on D will affect the state of the flip-flop.

T-type flip-flop
This type of flip-flop also has a clock input as well as an input named T. When T is high and the clock input goes high, the T-type flip-flop will toggle its state. One application of this is a divide-by-2 circuit where an applied frequency (on the clock input) gets divided by 2.


  • Shift registers
  • Data storage
  • Data latch

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