Understanding Flip Flop Conversions

Sep 11, 2024

Flip Flop Conversion Lecture Notes

Introduction

  • Welcome to ALL ABOUT ELECTRONICS
  • Topic: Flip flop conversions
  • Previous knowledge: Types of flip flops (SR, D, JK, T)

Importance of Flip Flop Conversion

  • Designed a circuit with SR flip flop, but only JK flip flop available?
  • Knowledge of conversion helps avoid redesigning the entire circuit.
  • Use logic gates to convert one flip flop type to another.

Basic Concept of Flip Flop Conversion

  • A combinational circuit is needed for conversion.
  • Block diagram:
    • Output from existing flip flop to combinational circuit.
    • Inputs of desired flip flop to the same combinational circuit.
    • Example: Convert SR flip flop to JK flip flop using J, K inputs.

Possible Flip Flop Conversions

  • 4 types of flip flops = 12 possible conversions.
  • Focus: SR to JK, D, T flip flop conversions.

SR to JK Flip Flop Conversion

JK Flip Flop Truth Table

  • J=0, K=0: Next state same as present state.
  • J=0, K=1: Reset to 0.
  • J=1, K=0: Set to 1.
  • J=1, K=1: Toggle output.

SR Flip Flop Excitation Table

  • 0 to 0: S=0, R=X (X = 0 or 1)
  • 0 to 1: S=1, R=0
  • 1 to 0: S=0, R=1
  • 1 to 1: S=X, R=0

Deriving Inputs for Conversion

  • Find relations for S and R in terms of J, K, and Qn.
  • S = J.Qn'
  • R = K.Qn
  • Use AND gates to implement the conversion.

SR to D Flip Flop Conversion

D Flip Flop Truth Table

  • Output Qn+1 = D input.
    • D=0: Qn+1=0
    • D=1: Qn+1=1

Required S and R Inputs

  • 0 to 0: S=0, R=X
  • 1 to 0: S=0, R=1
  • 0 to 1: S=1, R=0
  • 1 to 1: S=X, R=0

Deriving Inputs for Conversion

  • S = D
  • R = D'
  • Convert using one NOT gate.

SR to T Flip Flop Conversion

T Flip Flop Truth Table

  • T=0: Retain current state.
  • T=1: Toggle the output.

Required S and R Inputs

  • 0 to 0: S=0, R=X
  • 1 to 1: S=X, R=0
  • 0 to 1: S=1, R=0
  • 1 to 0: S=0, R=1

Deriving Inputs for Conversion

  • S = T.Qn'
  • R = T.Qn
  • Implement with two AND gates.

Conclusion

  • Basic technique for flip flop conversion explained.
  • Discussed conversions for SR to JK, D, and T flip flops.
  • Next video: JK flip flop conversions.
  • Questions and suggestions can be left in comments.