Page 153 - DCAP108_DIGITAL_CIRCUITS_AND_LOGIC_DESIGNS

Digital Circuits and Logic Design Avinash Bhagat, Lovely Professional University

Notes Unit 9: Flip-Flops

CONTENTS
Objectives
Introduction
9.1 Basic Flip-Flop Circuit
9.2 Types of Flip-Flop
9.2.1 Clocked SR Flip-Flop
9.2.2 JK Flip-Flop
9.2.3 T Flip-Flop

9.2.4 D Flip-Flop
9.3 Master-Slave Flip-Flop
9.4 Triggering of Flip-Flop
9.5 Timing Signal
9.6 Summary
9.7 Keywords
9.8 Review Questions

9.9 Further Readings

Objectives

After studying this unit, you will be able to:
• Describe the flip-flop circuit
• Explain the types of flip-flop
• Discuss the master slave flip-flop
• Describe the triggering of flip-flops
• Explain the timing signal

Introduction

Flip-flops; not the sandals, but the logic gates, are the fundamental building blocks of sequential
logic. There are a variety of different flip-flop types and configurations. In this activity, and this
course for that matter, we will only be studying two, the D flip-flop and the J/K flip-flop. After
reviewing the basic operation of the 74LS74 D and the 74LS76 J/K flip-flops, this activity will
examine two introductory applications of flip-flops.
Note: Where did the flip-flops get their name? The D in the D flip-flop stands for data. No one
is absolutely sure where the J/K name originated, but one theory is that it is named after Jack
Kilby, the inventor of the integrated circuit.
A timing signal generating device operates in response to angular displacement of a rotating
shaft. The shaft has a disc provided with a reference mark and a plurality of timing marks apart
from one another in a circumferential direction. A first detector is located adjacent to the disc to
detect the reference mark and to reset a shift register. A second detector is also located adjacent

148 LOVELY PROFESSIONAL UNIVERSITY