Latches

Table of contents

  1. Introduction
  2. Differences between latches and flip-flops
  3. Sub-modules

Introduction

There are two types of memory elements based on the type of triggering that is suitable to operate it.

  1. Latches
  2. Flip-flops

Latches operate with enable signal, which is level sensitive. Whereas, flip-flops are edge sensitive. Let’s discuss about flip-flops in next module. Latches are basic storage elements that operate with signal levels (rather than signal transitions). They are level-sensitive devices, that are useful for the design of the asynchronous sequential circuits. They, generally, have 2 inputs and 1 output pins. And the process where the output of the circuit depends on the previous state and the present input value(s) supplied, with the output value being constant (changing only for a particular condition in the input(s)), is referred to as latching.

Differences between latches and flip-flops

Latches Flip-flops
Level triggered Edge triggered
Asynchronous device Synchronous device
Doesn’t contain clock signal Contains a clock signal
It will change its state as long as it is enabled It will change its state only during a given clock cycle
Consumes less power Consumes more power
Faster Slower
Examples: D-Latch, T-Latch Examples: D-Flip flop, T-Flop flop

Sub-modules

Now, let us discuss about SR Latch, D Latch, JK Latch & T Latch one by one.

  1. SR latch
  2. D latch
  3. JK latch
  4. T latch