1. Sequential Circuits1 SEQUENTIAL CIRCUITS

2. Sequential Circuits2 Two Types of Switching Circuits Combinational Circuits –Combinational circuits have only input and output. Output depends on input. –Example: AND,OR,NAND,NOR,XOR etc Sequential Circuits –Sequential circuits have input, present state, next state and output. Next state depends upon present state and input. Output depends upon present state and input –Example: Flip-Flops etc

3. Sequential Circuits3 FLIP FLOPS AND THEIR APPLICATIONS 1.

4. Sequential Circuits4

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9. 9 When S = 1, Q + = 1 When R = 1, Q + = 0 When T = 1, State changes When any two out of S,R,T equals 1, we have don’t care

10. Sequential Circuits10

11. Sequential Circuits11 Example 1: Design a modulo-8 binary -up counter using T- Flip Flop Modulo 8 counter : Counts upto 7. So we need three Flip-flops for eight states

12. Sequential Circuits12 modulo-8 counter

13. Sequential Circuits13 modulo-8 counter

14. Sequential Circuits14 modulo-8 counter

15. Sequential Circuits15 modulo-8 counter

16. Sequential Circuits16 Modulo 8 counter : Counts upto 7. So we need three Flip-flops for eight states Example 2: Design a modulo-8 binary -up counter using T- Flip Flop with input x

17. Sequential Circuits17 modulo 8 counter with I/p x

18. Sequential Circuits18 modulo 8 counter with I/p x

19. Sequential Circuits19 modulo 8 counter with I/p x

20. Sequential Circuits20 modulo 8 counter with I/p x

21. Sequential Circuits21 Example 3: Design a binary decade counter using SR- Flip Flop without input x Decade Counter: Counts up to 9. So we need four Flip-Flops for ten states

22. Sequential Circuits22 Binary Decade counter

23. Sequential Circuits23 Binary Decade counter

24. Sequential Circuits24 Binary Decade counter

25. Sequential Circuits25 Binary Decade counter

26. Sequential Circuits26 Binary Decade counter

27. Sequential Circuits27 Example 4: Design a modulo-8 counter which counts in the way specified below, use J-K Flip-Flop.

28. Sequential Circuits28 TRUTH TABLE: present statenext state

29. Sequential Circuits29 Gray code counter Y3Y3

30. Sequential Circuits30 Y2Y2 Gray code counter:

31. Sequential Circuits31 Y1Y1 Gray code counter:

32. Sequential Circuits32 Example 5: Design a T-Flip-Flop using S-R Flip-Flop Sol:

33. Sequential Circuits33 T Flip flop using S-R flipflop

34. Sequential Circuits34 Example 6: Design a J-K Flip Flop using S-R Flip Flop Sol:

35. Sequential Circuits35 J-K Flip Flop using S-R Flip Flop

36. Sequential Circuits36 Example 7: Design a sequential circuit given below using J-K FlipFlop

37. Sequential Circuits37 Truth Table: Present st.Next stateo/p I/p

38. Sequential Circuits38 Design of Seq. Circuit

39. Sequential Circuits39 Design of Seq. Circuit

40. Sequential Circuits40 Design of Seq. Circuit

41. Sequential Circuits41 Design of Seq. Circuit

42. Sequential Circuits42 Example 8: Design a binary modulo-5 counter using SRT- Flip Flop with input x Modulo-5 Counter: Counts up to 4. So we need three Flip- Flops for five states

43. Sequential Circuits43 STATE TABLE Binary Modulo-5 counter

44. Sequential Circuits44 Binary Modulo-5 counter

45. Sequential Circuits45 Binary Modulo-5 counter

46. Sequential Circuits46 Note: Here S’and C’ stands for the compliment value of the corresponding cells in the S and C K-maps Binary modulo-5 counter Assume T’ = So S’ and C’ comes out to be

47. Sequential Circuits47 Binary Modulo-5 counter

48. Sequential Circuits48 Assume T’ = So S’ and C’ comes out to be Binary modulo-5 counter

49. Sequential Circuits49 Binary modulo-5 counter

50. Sequential Circuits50 Assume T’ = 1 So S’ and C’ comes out to be 0 and 0 Binary modulo-5 counter

51. Sequential Circuits51 G = 0 Q + does not respond G = 1 Q + responds

52. Sequential Circuits52 T-G Flip Flop Application Equation This is the Application Equation of the T-G Flip-Flop

53. Sequential Circuits53 Example 9: Design T2 and G2 for a modulo-5 binary up counter Modulo-5 counter: Counts up to 4. So we need three Flip- Flops for five states

54. Sequential Circuits54 STATE TABLE Modulo 5 binary upcounter

55. Sequential Circuits55 Modulo 5 binary upcounter

56. Sequential Circuits56 Modulo 5 binary upcounter

57. Sequential Circuits57 Modulo 5 binary upcounter

58. Sequential Circuits58 Modulo 5 binary upcounter

59. Sequential Circuits59 Example 10: Design an Octal upcounter(Binary counter) using S-C Flip-Flop using Tabular Method Octal up counter: Counts up to 7. So we need three Flip- Flops for seven states

60. Sequential Circuits60 STATE TABLE Octal up counter

61. Sequential Circuits61 Octal up counter

62. Sequential Circuits62 Octal up counter

63. Sequential Circuits63 Octal up counter

64. Sequential Circuits64 RULES TO DERIVE EXCITATION FUNCTION T- Flip-Flop

65. Sequential Circuits65 S-C Flip Flop

66. Sequential Circuits66 J-K Flip Flop

67. Sequential Circuits67 T-G Flip Flop

68. Sequential Circuits68 S-C-T Flip Flop

69. Sequential Circuits69 Summary of Rules for all Flip-Flops

70. Sequential Circuits70 MODIFIED RULES FOR THE FLIP-FLOPS

71. Sequential Circuits71 questions ???