This document discusses sequential logic circuits and flip-flops. It describes how sequential logic uses inputs and outputs where states depend on previous states. A common example is a flip-flop, which can store one bit of information and only change value at a positive clock edge, holding its value otherwise. There are different types of flip-flops including RS, JK, D, and T flip-flops. D flip-flops can be made from RS flip-flops with an inverter, while T flip-flops toggle the output value with each trigger.

1. SEQUENTIAL LOGICS
 A form of binary circuit design.
 Employs one or more inputs and one or more
outputs.
 States are related by defined rules that depend, in
part, on previous states.
 Each of the input(s) and output(s) can attain either
of two states: logic 0 (low) or logic 1 (high).
 EXAMPLE: A common example is flip-flop.

2. FLIP-FLOP
 A device that can store 1 bit of information.
 It is a clocked device, which can change its value
only at positive clock edges.
 When the clock is not at a positive edge, the flip-
flop maintains (holds) its value.

3. Q
Q’
Inputs
Normal Output
Inverted Output
 They have two stable sates and can be switched from
one to the other by appropriate inputs.
 These stable conditions are usually called the states
of the circuit.

4. TYPES OF FLIP-FLOPS
There are four types of flip-flops.
 Basic RS flip-flop
 Clocked RS flip-flop
 JK flip-flop
 D flip-flop
 T flip-flop
 Master slave flip-flop

5. D FLIP-FLOP
 Also known as data flip-flop.
 Can be constructed from RS flip-flop by adding an
inverter.
 Inverter is added so that the R input is always the inverse
of S(or J input is always complementary of K).

6. CIRCUIT DIAGRAM
D
Cp
D’
Q
Q’

7. D Q Q (New) Operations
0 0 0 Reset
0 1 0 Reset
1 0 1 Set
1 1 1 Set
TRUTH TABLE

8. T FLIP-FLOP
 Also known as toggle flip-flop.
 It has only the toggle and hold operation.
 If toggle mode operation. The output will toggle from 1 to
0 or vice versa.

9. T
Q
Cp
Q’
T
CIRCUIT DIAGRAM

10. T Q Q(new) Operations
0 0 0 Hold
0 1 1 Hold
1 0 1 Toggle
1 1 0 Toggle
TRUTH TABLE