State table and characteristic equation for sequential circuit
- 1. DIGITAL ELECCTRONICS State Diagram & Characteristics Eq. of Sequential Circuit PREET|patel (151310109032) 2nd Year B.E. Electrical AIIE
- 2. CONTENTS: • INTRODUCTION • JK FLIP FLOP • D FLIP FLOP • SR FLIP FLOP • T FLIP FLOP • Conversion from SR FF to T FF
- 3. INTRODUCTION • We use the truth table for explaining the relation between its inputs and outputs of a circuit combinational. • But the use of truth table is not suitable for explaining the input output relation for a sequential circuit. • Instead we use the STATE TABLE for the sequential circuits. The basic building block of a sequential circuit is a flip flop. The outputs QA, QB etc. of such flip flops will be used as state inputs to a sequential circuit. They are also called as state variable. • In addition to this "x" represents an external input and Y represents the output of the sequential circuit. • Y will be dependent on the state variables and the external input x.
- 4. JK FLIP FLOP Truth table
- 5. JK FLIP FLOP P.S N.SI/P S0 S1 0/0 0/1 0/X QN J K QN 0 0 X 0 0 1 X 1 1 X 1 0 1 X 0 1 Excitation table
- 6. STATE EQUATION • State equation is the combination of P.S and I/P to the flip-flop. STATE Equation JK flip flop Qn+1 = QnJ + QnK
- 7. D FLIP-FLOP CHRACHTERISTIC TABLE D QT QT+1 0 0 0 0 1 0 1 0 1 1 1 1 D CLK
- 8. STATE EQUATION • State equation is for D FLIP-FLOP is given by : QT+1= DQ + DQ QT+1 = D
- 9. SR FLIP-FLOP CHRACHTERISTIC TABLE QN S R QN 0 0 X 0 0 1 0 1 1 0 1 0 1 X 0 1
- 10. T-FLIP FLOP CHRACHTERISTIC TABLE T QT QT+1 0 0 0 1 0 1 1 1 0 0 1 1
- 11. CONVERSION FROM SR FF TO T FF INPUT OUTPUTS T P.S Qn N.S Qn+1 S R 0 0 0 0 X 1 0 1 1 0 1 1 0 0 1 0 1 1 X 0 0 X 1 0 X 0 0 1 T Qn T Qn S=TQn R=TQn
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