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UNIT 4-p1

The document covers the fundamentals of sequential circuits, including synchronous and asynchronous types, latches, and flip-flops. It details various flip-flop types such as SR, D, JK, and T flip-flops, along with their characteristic equations and timing diagrams. Additionally, it discusses the analysis and design procedures for both synchronous and asynchronous sequential circuits.

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Sandhya Gandham
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15 views36 pages

UNIT 4-p1

The document covers the fundamentals of sequential circuits, including synchronous and asynchronous types, latches, and flip-flops. It details various flip-flop types such as SR, D, JK, and T flip-flops, along with their characteristic equations and timing diagrams. Additionally, it discusses the analysis and design procedures for both synchronous and asynchronous sequential circuits.

Uploaded by

Sandhya Gandham
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Sequential Circuits and Systems: Synchronous

Sequential Circuits,
Latches, Flip-flops,
Analysis of clocked sequential circuits,
Registers, Shift registers,
Ripple counters, Synchronous counters, other
counters and Applications of counters.
Asynchronous Sequential Circuits -
Introduction,
Analysis procedure,
Circuits with latches,
Design procedure.
Sequential circuits
Types of Sequential circuits
• Synchronous sequential circuits
•Asynchronous sequential circuits
Latches
Storage elements that operate with signal
levels (rather than signal transitions) are
referred to as latches ; those controlled by a
clock transition are flip-flops. Latches are
said to be level sensitive devices; flip-flops
are edge-sensitive devices. The two types of
storage elements are related because
latches are the basic circuits from which all
flip-flops are constructed.
SR Latch
D Latch (Transparent Latch)
Flip-flops
Types of Flip-flops

• SR Flip-Flop
• D Flip-Flop
• JK Flip-Flop
• T Flip-Flop
SR Flip-flop
D Flip-flop
The characteristic equation for the D Flip-flop is
Q(t + 1) = D
Clock Edges

Positive Edge Transition

Negative Edge Transition

25
D Flip-Flop: Example Timing

Q=D=1 Q=D=0 Q=D=0 Q=D=1 Q=D=1 Q=D=0 Q=D=0


No Change No Change No Change

CLK
Flip-Flop Timing
1
Data Input
(D,J, or K)
0

tS tH
Setup Time Hold Time
Positive 1
Edge
Clock 0

Setup Time (tS): The time interval before the active transition of the clock
signal during which the data input (D, J, or K) must be maintained.

Hold Time (tH): The time interval after the active transition of the clock
signal during which the data input (D, J, or K) must be maintained.

Propagation delay: It is defined as the interval between the trigger edge


and the stabilization of the output to a new state.
JK Flip-flop
The characteristic equation for the JK Flip-flop is
Q(t + 1) = JQ’ + K’Q
J/K Flip-Flop: Example Timing

NO NO
SET TOGGLE TOGGLE CLEAR CHANGE SET CHANGE

CLK

31
T Flip-flop
The characteristic equation for the T Flip-flop is
Q(t + 1) = =TQ’ + T’Q
Direct Inputs
Excitation Tables

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