In electronic flip flop a basic component, As we all know that digital electronics is being getting popularized each day. We know there are two types of signals: analog and digital. But working with analog signal is not so easy (as in analog we get infinite values but we don’t need infinite value and also noise is associated with analog signal) so we prefer to work with digital signal. The branch of electronics which deals with digital signal is called “DIGITAL ELECTRONICS”. In this article we will discuss the flip flops which are very integral part of digital electronics
What is flip flop?
Flip flop or latch is a bi-stable multi-vibrator i.e. it has two stable states and is used for storing information. Flip flops and latches are fundamental building blocks of digital electronics. The first flip flop was made by William Eccles and Jordan and at that time it was called ECCLES-JORDAN TRIGGER CIRCUIT.
There are four types of flip flops:
- SR flip flops (set reset flip flop)
- JK flip flops (Jack Kilby flip flop :named after scientist who made it)
- D flip flops (data flip flop)
- T flip flops (toggle flip flop)
As we know in sequential circuits, there output depends on present input as well as past output, so for storing the past output they need memory elements or flip flops so they are used in all sequential circuits.
SR flip flops
In this we have two inputs S and R, when s and r both are zero; we get previous output as output. When s is one and r is zero we get one as output, when s is zero and r is one we get zero as output. When s and r both are one we get indefinite output that means it is practically not possible to set and reset a device at the same time.
It can be implemented simply by using two NAND or NOR gates.
JK flip flops
To overcome the indefinite problem in SR we use JK flip flop. JK flip flop is just a modification of SR flip flop. If we connect the output of SR i.e. Q and Q’ as a feedback we will get JK flip flop. In this if J and K both are one we get the toggled output.
D flip flops
This is the simplest flip flop, whatever is the input we get same output.
T flip flops
In this flip flop whatever is the input we get toggled output. For example 0 is input we will get 1 as output and vice versa.
Types of flip flops (Triggering)
This was all about types of flip flop. Now there are two ways by which we can trigger them:
- Level triggered
- Edge triggered
In level triggering, the flip flop is active throughout a level that means till the positive cycle of analog signal but in edge triggering the flip flop is active only during rising edge or falling edge.
Generally we follow edge triggering as it solves the race around problem (race around problem is nothing it is just the continuous changing of outputs as flip flop is active for longer period of time, it is generally seen in level triggering).
Application of flip flops
The main function of register is to store and move data. If we cascade n flip flops we can store n bit data. That means to store 1110 we need four flip flops. They are categorized in two categories:
- On the basis of data movement
- Right shift register
- Left shift register
- Universal shift register
- On the basis of input and output
- SISO (serial in serial out)
- SIPO (serial in parallel out)
- PIPO (parallel in parallel out)
- PISO (parallel in serial out)
Counters are circuits which counts number of events arriving at its clock input. The main difference between a counter and a register is that a pattern is followed in the output of a counter and that pattern is absent in registers. They are also of many types like ring counter, johnson counter etc.
A combination of flip flop can also be used in detecting an event. Suppose you have a data 10101110101110 and you want to check how many times 101 came together. You can do this with flip flops.
enjoy learning …..