Flip-flops

MCS-012 Computer Organisation and Assembly Language Programming

                                 Basics and Overview of Flip Flops

A flip flop is an electronic circuit with two stable states that can be used to store binary data.
The stored data can be changed by applying varying inputs. Flip-flops and latches are fundamental
building blocks of digital electronics systems used in computers, communications, and many other
types of systems. Flip-flops and latches are used as data storage elements. It is the basic storage
element in sequential logic. But first, let’s clarify the difference between a latch and a flip-flop.

                                                        Flip flop v/s Latch
The basic difference between a latch and a flip-flop is a gating or clocking mechanism.

For example, let us talk about SR latch and SR flip-flops. In this circuit when you Set S as active
the output Q would be high and Q’ will be low. This is irrespective of anything else.
(This is an active-low circuit so active here means low, but for an active high circuit active would mean high)


SR Flip Flop
There are majorly 4 types of flip flops, with the most common one being
SR flip flop. This simple flip flop circuit has a set input (S) and a reset
input (R). In this circuit when you Set “S” as active the output “Q” would be
high and “Q‘‘” will be low. Once the outputs are established, the wiring of the
circuit is maintained until “S” or “R” go high, or power is turned off. As shown
above, it is the simplest and the easiest to understand. The two outputs, as shown
above, are the inverse of each other. The truth table of SR Flip Flop is highlighted below.

JK Flip-flop
Due to the undefined state in the SR flip flop, another flip flop is required in electronics.
The JK flip flop is an improvement on the SR flip flop where S=R=1 is not a problem

The input condition of J=K=1, gives an output inverting the output state.
However, the outputs are the same when one tests the circuit practically.

In simple words, If J and K data input are different (i.e. high and low) then
the output Q takes the value of J at the next clock edge. If J and K are both
low then no change occurs. If J and K are both high at the clock edge then the
output will toggle from one state to the other. JK Flip Flop can function as Set or Reset Flip flop

D flipflop
D flip flop is a better alternative that is very popular with digital electronics.
They are commonly used for counters and shift-registers and input synchronisation
In a D flip flop, the output can be only changed at the clock edge, and if the input
changes at other times, the output will be unaffected
The change of state of the output is dependent on the rising edge of the clock.
The output (Q) is same as the input and can only change at the rising edge of the clock.

T Flip Flop
A T flip flop is like JK flip-flop. These are basically a single input version of JK flip flop. This
modified form of JK flip-flop is obtained by connecting both inputs J and K together. This
flip-flop has only one input along with the clock input.

These flip-flops are called T flip-flops because of their ability to complement its state
(i.e.) Toggle, hence the name Toggle flip-flop.

Applications of Flip-Flops
These are the various types of flip-flops being used in digital electronic circuits and the
applications of Flip-flops are as specified below.

Counters
Frequency Dividers
Shift Registers
Storage Registers

https://electronicsforu.com/resources/learn-electronics/flip-flop-rs-jk-t-d





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