Latches vs Flipflops: Difference and Comparison

Key Takeaways

1. Latches and flip-flops are used in digital circuits to store binary information but have different operating principles. Latches are level-sensitive devices that hold data when enabled, while flip-flops are edge-triggered devices that respond to specific clock transitions.
2. Latches are controlled by enable signals, while clock signals control flip-flops. Latches can be affected by glitches and small input changes during their active phase. In contrast, flip-flops are designed to respond reliably at specific clock transitions, making them more immune to noise.
3. Latches are commonly used for temporary storage, data synchronization, and small memory elements, while flip-flops are used for sequential circuit design, memory units, and implementing registers. The choice between latches and flip-flops depends on timing requirements, robustness against glitches, and the need for synchronization in a specific circuit.

What is a Latch?

The Latch is an electronic logic circuit with two inputs and two outputs, and it changes its output immediately based on the applied input. It can be designed using logic gates. Latch checks input continuously and responds to the input change immediately. The two inputs in the latch are SET and RESET, with two outputs.

The latch is a bistable device, i.e., it has two stable states represented by 0 and 1. It uses only binary inputs. It is also known as a bistable- multivibrator. It is also a memory device that can store one bit of data. It stores data by using a feedback lane. It is not synchronous and does not work on the edge of the clock. The latch is a level-sensitive device. It has a fast operating speed and requires less power to operate.

Latches are widely used in computing and data storage, and power-gating circuits. They can be used to design asynchronous sequential circuits. Some common types of latches are S-R Latch, Gated S-R Latch, D latch, Gated D Latch, J-R Latch, and T latch.

What is a Flip-Flop?                                                                             

A flip-flop is an edge-triggered device that uses gates like NOR, NOT, AND, and NAND. It is a digital memory circuit that is the fundamental building block of any digital electronic device. Flip-flop performs synchronous operations and can be created using clock latches.

It is a bistable device that uses binary inputs and clock signals. It checks input continuously but changes the output only at a time defined by a control or clock signal. The state of a flip-flop is changed only when the clock pulse is active; otherwise, it remains unchanged. The output in sequential circuits is obtained from the combinational circuit, flip-flop, or both. It is easy to perform an analysis of the circuit in flip-flops.

Flip-flops are widely used in digital electronics, computers, communications, and other systems. A flip-flop can be used as a memory element in sequential circuits. It can also be used in working as a register. Some common flip-flops are S-R Flip-flops, T (toggle) Flip-flops, D (Delay) Flip-flops, and J-K Flip-flops, also known as universal Flip-flops.

Difference Between Latch and Flip-flop

1. Latch is a level-triggered device, whereas flip-flop is an edge-triggered device.
2. Latch only requires binary input, whereas flip-flop requires binary input and a clock signal.
3. Latch checks input continuously and responds to the change in input immediately, whereas flip-flop changes the output only at a time defined by the clock signal.
4. Latch performs an asynchronous operation, whereas flip-flop performs a synchronous operation.
5. Latch has a fast operating speed, whereas flip-flop is slow.
6. It is not easy to perform an analysis of the circuit in latches, whereas it is easy to perform an analysis of the circuit in flip-flops.

Comparison Between Latch and Flip-flop

Parameters of Comparison	Latch	Flip Flop
Type of device	In Latch, only  binary input is required	It is an edge-triggered device
Working Requirements	In Latch only  binary input is required	Flip-flop requires binary input and a clock signal
Input and Output	It responds to the change in input immediately	It changes the output only at a time defined by the clock signal
Operation	It performs an asynchronous operation	It performs a synchronous operation
Operating Speed	Operating speed is fast	Operating Speed is slow

References

1. https://ieeexplore.ieee.org/abstract/document/727060
2. https://www.sciencedirect.com/science/article/abs/pii/S0045790622004281