Functional block, characteristics of 555 Timer and its PWM application – IC-566 voltage controlled oscillator IC; 565-phase locked loop IC, AD633 Analog multiplier ICs.
Linear Integrated Circuits and Its Applications Unit-V Special ICsSatheeshCS2
Linear Integrated Circuits and Its Applications
Unit-V Special ICs
Mr. C.S.SATHEESH, M.E.(Control Systems),
Assistant Professor, Department of EEE, Muthayammal Engineering College, (Autonomous) Namakkal (Dt), Rasipuram – 637408
this presentation is about transistor and its type, how transistor works, what is the importance of the transistor in our world and what was use before transistor.
INTERFACING ANALAOG TO DIGITAL CONVERTER (ADC0808/09) TO 8051 MICROCONTROLLER SIRILsam
INTERFACING ANALAOG TO DIGITAL CONVERTER (ADC0808/09) TO 8051 MICROCONTROLLER . LEARN HOW ADC WORKS ,SUCCESSIVE APPROXIMATION METHOD . DIGITAL DATA OUTPUT CALCULATION
This presentation contains the basic information you need to know about operational amplifier.
I have tried to cover all the basic info. If anything is left out or you have any suggestions i will appreciate it.
Linear Integrated Circuits and Its Applications Unit-V Special ICsSatheeshCS2
Linear Integrated Circuits and Its Applications
Unit-V Special ICs
Mr. C.S.SATHEESH, M.E.(Control Systems),
Assistant Professor, Department of EEE, Muthayammal Engineering College, (Autonomous) Namakkal (Dt), Rasipuram – 637408
this presentation is about transistor and its type, how transistor works, what is the importance of the transistor in our world and what was use before transistor.
INTERFACING ANALAOG TO DIGITAL CONVERTER (ADC0808/09) TO 8051 MICROCONTROLLER SIRILsam
INTERFACING ANALAOG TO DIGITAL CONVERTER (ADC0808/09) TO 8051 MICROCONTROLLER . LEARN HOW ADC WORKS ,SUCCESSIVE APPROXIMATION METHOD . DIGITAL DATA OUTPUT CALCULATION
This presentation contains the basic information you need to know about operational amplifier.
I have tried to cover all the basic info. If anything is left out or you have any suggestions i will appreciate it.
IC 555 TIMER Introduction, Modes & Application.pptxanindyapal288
Pin 1. – Ground, The ground pin connects the 555 timer to the negative (0v) supply rail.
• Pin 2. – Trigger, The negative input to comparator No 1. A negative pulse on this pin “sets” the internal Flip-flop when the voltage drops below 1/3Vcc causing the output to switch from a “LOW” to a “HIGH” state.
• Pin 3. – Output, The output pin can drive any TTL circuit and is capable of sourcing or sinking up to 200mA of current at an output voltage equal to approximately Vcc – 1.5V so small speakers, LEDs or motors can be connected directly to the output.
• Pin 4. – Reset, This pin is used to “reset” the internal Flip-flop controlling the state of the output, pin 3. This is an active-low input and is generally connected to a logic “1” level when not used to prevent any unwanted resetting of the output.
• Pin 5. – Control Voltage, This pin controls the timing of the 555 by overriding the 2/3Vcc level of the voltage divider network. By applying a voltage to this pin the width of the output signal can be varied independently of the RC timing network. When not used it is connected to ground via a 10nF capacitor to eliminate any noise.
• Pin 6. – Threshold, The positive input to comparator No 2. This pin is used to reset the Flip-flop when the voltage applied to it exceeds 2/3Vcc causing the output to switch from “HIGH” to “LOW” state. This pin connects directly to the RC timing circuit.
• Pin 7. – Discharge, The discharge pin is connected directly to the Collector of an internal NPN transistor which is used to “discharge” the timing capacitor to ground when the output at pin 3 switches “LOW”.
• Pin 8. – Supply +Vcc, This is the power supply pin and for general purpose TTL 555 timers is between 4.5V and 15V.
1.Introduction
The 555 IC was designed in 1971 by Hans Camenzind under contract to SigNetics Corporation.
555 timer is a highly stable circuit used to generate time delays, or Oscillations.
A single 555 timer can provide time delay ranging from microseconds to hours.
It operates from a wide range of power supplies ranging from + 5 Volts to + 18 Volts supply voltage.
2.Pin Configuration
3.Working of Pin
4.555 Integral circuit
5.Operating modes of IC
6. Bistable Mode
In bistable (also called Schmitt trigger) mode, the 555 timer acts as a basic flip-flop.
The trigger and reset inputs (pins 2 and 4 respectively on a 555) are held high via pull-up resistors while the threshold input (pin 6) is simply floating.
Thus configured, pulling the trigger momentarily to ground acts as a 'set' and transitions the output pin (pin 3) to Vcc (high state).
Pulling the reset input to ground acts as a 'reset' and transitions the output pin to ground (low state). No timing capacitors
Pin 5 (control voltage) is connected to ground via a small-value capacitor (usually 0.01 to 0.1 μF). Pin 7 (discharge) is left floating
7.Monostable Mode
Pulse generator circuit which the period is calculated from RC network and connected to external of 555 timer
Stable when the output logic LOW (logic = 0)
When a pulse is trigger at pin 2 (normally negative trigger pulse), timer output will change to HIGH (+Vs) for a while and change to LOW (stable condition). The condition will continue LOW until pulse is trigger again.
The timing period is triggered (started) when trigger input (555 pin 2) is less than 1/3 Vs, this makes the output high (+Vs) and the capacitor C1 starts to charge through resistor R1. Once the time period has started further trigger pulses are ignored.
The threshold input (555 pin 6) monitors the voltage across C1 and when this reaches 2/3 Vs the time period over and the output becomes LOW,
At the same time discharge (555 pin 7) is connected to 0V, discharging the capacitor ready for the next trigger.
8.Astable Mode
Astable multivibrators are also known as Free-running Multivibrator.
Astable do not need trigger pulse for external to change the output.
The period for LOW and HIGH can be calculated based on resistor and capacitor value that connected at outside of timer.
9.Applications
Schmitt trigger
PPM
PWM
Linear Ramp generator
Precision Timing
Pulse Generation
Time Delay Generation
Sequential Timing
Used as a quad timer
10. Conclusion
Hence 555 IC timer can produce very accurate and stable time delays, from microseconds to hours. It can be used with supply voltage varying from 5 to 18 V. Timer can be used in monostable mode of operation or astable mode of operation. Its various applications include waveform generator, missing pulse detector, frequency divider, pulse width modulator, burglar alarm, FSK generator, ramp generator, pulse position modulator etc.
SIMULATION OF AN ELECTRONIC DICE CIRCUIT USING LEDs IN PROTEUS SOFTWARE VaishaliVaishali14
The following content consists of the brief details about the topic
INTRODUCTION
CONCEPT OF ASTABLE MULTI VIBRATOR
CONCEPT OF DECADE COUNTER IC4017
CIRCUIT EXPLANATION
CIRCUIT DIAGRAM
VIDEO OF CIRCUIT WORKING
WORKING OF CIRCUIT
INFERENCE
REFERENCE
IC555 Timer, Monostable and Astable modes of operation; voltage regulators - fixed voltage regulators, adjustable voltage regulators - switching regulators.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
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Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
1. LINEAR INTEGRATED CIRCUITS &APPLICATIONS
UNIT Iv
special ic
Prepared by,
E.ELAKKIA & M.PERARASI,
ASSISTANT PROFESSOR/EEE,
R.M.K.ENGINEERING COLLEGE
17 April 2021 1
E.ELAKKIA/AP/EEE/RMKEC
2. SYLLABUS
Functional block, characteristics of 555 Timer and its PWM
application – IC-566 voltage controlled oscillator IC; 565-
phase locked loop IC, AD633 Analog multiplier ICs.
17 April 2021 2
E.ELAKKIA/AP/EEE/RMKEC
3. AGENDA
• 555 Timer - Functional block & characteristics
• 555 Timer- Astable & monostable
• IC-566 voltage controlled oscillator
• IC-565-phase locked loop IC
• AD633 Analog multiplier ICs.
17 April 2021 3
E.ELAKKIA/AP/EEE/RMKEC
4. OVERVIEW
• The 555 Timer, designed by Hans Camenzind in 1971, can be
found in many electronic devices starting from toys and
kitchen appliances to even a spacecraft.
• It is a highly stable integrated circuit that can produce
accurate time delays and oscillations.
• The 555 Timer has three operating modes, bistable,
monostable and astable mode.
17 April 2021 E.ELAKKIA/AP/EEE/RMKEC 4
5. 555 Timer
Introduction:
The 555 Timer is one of the most popular and versatile integrated circuits
ever produced!
It is a combination of digital and analog circuits.
It is known as the “time machine” as it performs a wide variety of timing
tasks.
Applications for the 555 Timer include:
• Ramp and Square wave generator
• Frequency dividers
• Voltage-controlled oscillators
• Pulse generators and LED flashers
5
6. 555 timer- Pin Diagram
The 555 timer is an 8-Pin D.I.L. Integrated Circuit or ‘chip’
Notch
Pin 1
6
7. 555 TIMER PIN CONFIGURATION
17 April 2021 E.ELAKKIA/AP/EEE/RMKEC 7
8. 555 timer- Pin Description
Pin Name Purpose
1 GND Ground, low level (0 V)
2 TRIG OUT rises, and interval starts, when this input falls below 1/3 VCC.
3 OUT This output is driven to approximately 1.7V below +VCC or GND.
4 RESET
A timing interval may be reset by driving this input to GND, but the
timing does not begin again until RESET rises above approximately
0.7 volts. Overrides TRIG which overrides THR.
5 CTRL "Control" access to the internal voltage divider (by default, 2/3 VCC).
6 THR The interval ends when the voltage at THR is greater than at CTRL.
7 DIS
Open collector output; may discharge a capacitor between intervals.
In phase with output.
8 V+, VCC Positive supply voltage is usually between 3 and 15 V. 8
9. 555 Timer
Description:
•Contains 25 transistors, 2 diodes and 16 resistors
• Maximum operating voltage 16V
• Maximum output current 200mA
If you input certain signals they will be processed / controlled in a
certain manner and will produce a known output.
INPUT PROCESS OUTPUT
• Best treated as a single component with required
input and output
9
11. Inside the 555 Timer
S R Q Q
0 0 No Change
0 1 0 1
1 0 1 0
1 1 X X
Threshold
Control Voltage
Trigger
Discharge
Vref
+
R
S Q
Q
Truth Table
Fig: Functional Diagram of 555 Timer
-
11
12. Inside the 555 Timer
Operation:
• The voltage divider has three equal 5K resistors. It
divides the input voltage (Vcc) into three equal
parts.
• The two comparators are op-amps that compare
the voltages at their inputs and saturate depending
upon which is greater.
• The Threshold Comparator saturates when the voltage
at the Threshold pin (pin 6) is greater than (2/3)Vcc.
• The Trigger Comparator saturates when the voltage at
the Trigger pin (pin 2) is less than (1/3)Vcc
12
13. Inside the 555 Timer
• The flip-flop is a bi-stable device. It generates two
values, a “high” value equal to Vcc and a “low” value
equal to 0V.
• When the Threshold comparator saturates, the flip flop is
Reset (R) and it outputs a low signal at pin 3.
• When the Trigger comparator saturates, the flip flop is Set
(S) and it outputs a high signal at pin 3.
• The transistor is being used as a switch, it connects
pin 7 (discharge) to ground when it is closed.
• When Q is low, Q bar is high. This closes the transistor
switch and attaches pin 7 to ground.
• When Q is high, Q bar is low. This open the switch and
pin 7 is no longer grounded
13
14. Uses of 555 timer
What the 555 timer is used for:
•To switch on or off an output after a certain time delay i.e.
Games timer, Childs mobile, Exercise timer.
•To continually switch on and off an output i.e.
warning lights, Bicycle indicators.
•As a pulse generator i.e.
To provide a series of clock pulses for a counter.
14
16. 555 TIMER- WORKING
• The first comparator negative input terminal is connected to
the 2/3 reference voltage at the voltage divider and the
external “control” pin, while the positive input terminal to
the external “Threshold” pin.
• On the other hand, the second comparator negative input
terminal is connected to the “Trigger” pin, while the positive
input terminal to the 1/3 reference voltage at the voltage
divider.
17 April 2021 E.ELAKKIA/AP/EEE/RMKEC 16
17. 555 TIMER- WORKING
• So using the three pins, Trigger, Threshold and Control, we can
control the output of the two comparators which are then fed to
the R and S inputs of the flip-flop.
• The flip-flop will output 1 when R is 0 and S is 1, and vice versa, it
will output 0 when R is 1 and S is 0. Additionally the flip-flop can
be reset via the external pin called “Reset” which can override
the two inputs, thus reset the entire timer at any time.
• The Q-bar output of the flip-flip goes to the output stage or the
output drivers which can either source or sink a current of 200mA
to the load. The output of the flip-flip is also connected to a
transistor that connects the “Discharge” pin to ground.
17 April 2021 E.ELAKKIA/AP/EEE/RMKEC 17
19. 555 Timer as Monostable Multivibrator
Description:
➢ In the standby state, FF holds
transistor Q1 ON, thus
clamping the external timing
capacitor C to ground. The
output remains at ground
potential. i.e. Low.
➢ As the trigger passes through VCC/3, the FF is set, i.e. Q bar=0, then
the transistor Q1 OFF and the short circuit across the timing
capacitor C is released. As Q bar is low , output goes HIGH. 19
20. 555 Timer as Monostable Multivibrator
Fig (a): Timer in Monostable Operation with Functional Diagram
Fig (b): Output wave Form of Monostable 20
21. Monostable Multivibrator- Description
• Voltage across it rises exponentially through R towards Vcc with a time constant
RC.
• After Time Period T, the capacitor voltage is just greater than 2Vcc/3 and the
upper comparator resets the FF, i.e. R=1, S=0. This makes Q bar =1, C rapidly to
ground potential.
• The voltage across the capacitor as given by,
sec
1
.
1
)
3
1
ln(
)
1
(
3
2
3
2
,
)
1
(
RC
T
RC
T
e RC
T
V cc
V cc
V cc
vc
T
t
e RC
t
V cc
vc
=
=
=
−
−
=
=
=
−
−
=
at
➢ If –ve going reset pulse terminal (pin
4) is applied, then transistor Q2-> OFF,
Q1-> ON & the external timing
capacitor C is immediately discharged.
21
22. Behavior of the Monostable
Multivibrator
The monostable multivibrator is constructed by adding an external
capacitor and resistor to a 555 timer.
The circuit generates a single pulse of desired duration when it receives
a trigger signal, hence it is also called a one-shot.
The time constant of the resistor-capacitor combination determines the
length of the pulse.
22
23. Uses of the Monostable Multivibrator
• Used to generate a clean pulse of the correct height and duration for a
digital system
• Used to turn circuits or external components on or off for a specific
length of time.
• Used to generate delays.
• Can be cascaded to create a variety of sequential timing pulses. These
pulses can allow you to time and sequence a number of related
operations.
23
27. Missing Pulse Detector- Description
• When input trigger is Low, emitter-base diode of Q is
forwarded biased capacitor is clamped to 0.7v(of
diode), output of timer is HIGH width of T o/p of
timer > trigger pulse width.
• T=1.1RC select R & C such that T > trigger pulse.
• Output will be high during successive coming of
input trigger pulse. If one of the input trigger pulse
missing trigger i/p is HIGH, Q is cut off, timer acts as
normal monostable state.
• It can be used for speed control and measurement.
27
29. Linear Ramp Generator- Description
i
Q3
Applying KVL around base-emitter loop of Q3
)
(
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1
(
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R
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R
C
E
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C
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B
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B
E
B
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E
B
C
E
E
BE
CC
=
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=
+
=
+
=
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=
=
−
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(
2
1
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1
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1
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1
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( R
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V
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BE
CC
BE
CC
E i
i
+
+
−
=
+
+
−
=
t
C
dt
C
idt
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R
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v
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t
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t
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}
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BE
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T
+
−
+
=
When becomes at T,
vc VCC
3
2
Voltage Capacitor,
Ic
Analysis:
29
30. 3.Frequency Divider
Fig: Diagram of Frequency Divider
Description:
A continuously triggered monostable circuit
when triggered by a square wave generator can be used
as a frequency divider, if the timing interval is adjusted
to be longer than the period of the triggering square
wave input signal.
The monostable multivibrator will be
triggered by the first negative going edge of the square
wave input but the output will remain HIGH(because of
greater timing interval) for next negative going edge of
the input square wave as shown fig.
30
32. Pulse Width Modulation- Description
The charging time of capacitor is entirely depend upon 2Vcc/3.
When capacitor voltage just reaches about 2Vcc/3 output of the timer
is coming from HIGH to Low level.
We can control this charging time of the capacitor by adding
continuously varying signal at the pin-5 of the 555 timer which is
denoted as control voltage point. Now each time the capacitor voltage
is compared control voltage according to the o/p pulse width change.
So o/p pulse width is changing according to the signal applied to
control voltage point. So the output is pulse width modulated form.
32
34. Astable Multivibrator
34
1 – Ground 5 – FM Input (Tie to gnd via bypass cap)
2 – Trigger 6 – Threshold
3 – Output 7 – Discharge
4 – Reset (Set HIGH for normal operation) 8 – Voltage Supply (+5 to +15 V)
Fig (a): Diagram of Astable Multvibrator
35. Astable Multivibrator- Description
35
➢ Connect external timing capacitor between trigger point (pin 2) and Ground.
➢ Split external timing resistor R into RA & RB, and connect their junction to
discharge terminal (pin 7).
➢ Remove trigger input, monostable is converted to Astable multivibrator.
➢ This circuit has no stable state. The circuits changes its state alternately.
Hence the operation is also called free running oscillator.
36. Astable Multivibrator
36
Fig (b): Functional Diagram of Astable Multivibrator using 555 Timer
A1
A2
V1
V2
VT
VC
Vo
VA
R2
R1
R3
A1
A2
Q1
41. 41
• Resistive voltage divider (equal resistors) sets threshold voltages for
comparators
V1 = VTH = 2/3 VCC V2 = VTL = 1/3 VCC
• Two Voltage Comparators
- For A1, if V+ > VTH then R =HIGH
- For A2, if V- < VTL then S = HIGH
• RS FF
- If S = HIGH, then FF is SET, = LOW, Q1 OFF, VOUT = HIGH
- If R = HIGH, then FF is RESET, = HIGH, Q1 ON, VOUT = LOW
• Transistor Q1 is used as a Switch
Astable 555 Timer Block Diagram Contents
Q
Q
42. 42
Operation of a 555 Astable
VCC
VC(t)
RA RB
1) Assume initially that the capacitor is discharged.
a) For A1, V+ = VC = 0V and for A2, V- = VC = 0V, so R=LOW,
S=HIGH, = LOW , Q1 OFF, VOUT = VCC
b) Now as the capacitor charges through RA & RB,
eventually VC > VTL so R=LOW & S=LOW.
FF does not change state.
Q
43. 43
Operation of a 555 Astable
Continued……
VC(t)
RB
Q1
2) Once VC VTH
a) R=HIGH, S=LOW, = HIGH ,Q1 ON, VOUT = 0
b) Capacitor is now discharging through RB and Q1 to
ground.
c) Meanwhile at FF, R=LOW & S=LOW since
VC < VTH.
Q
44. 44
Operation of a 555 Astable
Continued…..
3) Once VC < VTL
a) R=LOW, S=HIGH, = LOW , Q1 OFF, VOUT = VCC
b) Capacitor is now charging through RA & RB again.
VCC
VC(t)
RA RB
Q
45. Output = High
45
tHIGH : Calculations for the Oscillator’s HIGH Time
THE OUTPUT IS HIGH WHILE THE CAPACITOR
IS CHARGING THROUGH RA + RB.
( )C
R
R
0.693 B
A +
=
HIGH
t
46. 46
C
0.693RB
=
LOW
t
tLOW : Calculations for the Oscillator’s LOW Time
5v
3.333 v
Vc 1.666 v
0 v
→ tLOW
Output
HIGH
LOW
THE OUTPUT IS LOW WHILE THE CAPACITOR IS
DISCHARGING THROUGH RB.
Output = Low
47. Astable Multivibrator- Analysis
47
Contd….
The capacitor voltage for a low pass RC circuit subjected to a step input of Vcc volts is given by,
The time t1 taken by the circuit to change from 0 to 2Vcc/3 is,
)
1
( e
V
v RC
t
CC
c
−
−
=
RC
t
e
V
V RC
CC
CC
t
09
.
1
)
1
(
3
2
1
1
=
−
=
−
V
V CC
C
3
2
=
The time t2 to charge from 0 to vcc/3 is V
V CC
C
3
1
=
RC
t
e
V
V RC
CC
CC
t
405
.
0
)
1
(
3
2
2
=
−
=
−
So the time to change from Vcc/3 to 2Vcc/3 is, RC
RC
RC
t
t
tHIGH
69
.
0
405
.
0
09
.
1
2
1
=
−
=
−
=
So, for the given circuit, C
R
R
t B
A
HIGH
)
(
69
.
0 +
=
The output is low while the capacitor discharges from 2Vcc/3 to Vcc/3 and the voltage
across the capacitor is given by,
e
V
V RC
t
CC
CC −
=
3
2
3
…… Charging time
49. Astable Multivibrator- Analysis
49
C
R
t B
LOW
69
.
0
=
After solving, we get, t=0.69RC
For the given circuit,
Both RA and RB are in the charge path, but only RB is in the discharge path.
The total time period,
C
C
T R
R
R
t
t B
B
LOW
HIGH A 69
.
0
)
69
.
0 ( +
=
+
= +
C
C
C
C
T R
R
R
R
R
R
R
R A
A
A B
B
B
B
B
)
69
.
0
)
69
.
0
]
)
69
.
0 2
(
(
[( +
+
+ =
+
=
+
=
C
C
T
f
R
R
R
R A
A B
B
)
45
.
1
)
69
.
0
1
1
2
(
2
( +
+
=
=
=
Frequency,
Duty Cycle,
100
)
)
100
)
69
.
0
)
69
.
0
100
%
2
(
(
2
(
(
X
X
C
C
X
T
D
R
R
R
R
R
R
R
R
t
A
A
A
A
B
B
B
B
HIGH
+
+
+
+
=
=
=
100
)
100
)
69
.
0
69
.
0
100
%
2
(
2
(
X
X
C
C
X
T
D
R
R
R
R
R
R
t
A
A B
B
B
B
LOW
+
+
=
=
=
…… Discharging time
…….1.45 is Error Constant
50. IC 555 timer
50
Visit this link to view a simulation of the IC 555 in astable mode
http://www.williamson-labs.com/pu-aa-555-timer_slow.htm
How does the
charge and
discharge of
the capacitor
relate to the
blinking LED?
51. Period
The Period is the total time of an
on/off cycle and depends on the
values of RA, RB, and C
51
( )
( )
( )C
2
693
.
0
693
.
0
693
.
0
693
.
0
693
.
0
B
A
B
B
A
LOW
HIGH
B
LOW
B
A
HIGH
R
R
T
C
R
C
R
R
T
t
t
T
C
R
t
C
R
R
t
+
=
+
+
=
+
=
=
+
=
Calculate the period of the flashing light.
52. Frequency
The frequency of an oscillation
(or anything that exhibits a
repeating pattern) is inversely
proportional to the period
( )C
R
2
R
693
.
0
1
F
T
1
F
B
A
+
=
=
52
Calculate the frequency (or blinking rate) of the
flashing light.
Unit of Measure:
cycles/second = Hertz (Hz)
53. Behavior of the Astable Multivibrator
The astable multivibrator is simply an oscillator. The
astable multivibrator generates a continuous stream of
rectangular off-on pulses that switch between two
voltage levels.
The frequency of the pulses and their duty cycle are
dependent upon the RC network values.
The capacitor C charges through the series resistors RA
and RB with a time constant (RA + RB)C.
The capacitor discharges through RB with a time
constant of RBC
53
54. Uses of the Astable Multivibrator
• Flashing LED’s
• Pulse Width Modulation
• Pulse Position Modulation
• Periodic Timers
• Uses include LEDs, pulse generation, logic
clocks, security alarms and so on.
54
56. 1. FSK Generator
56
Description:
➢ In digital data communication, binary
code is transmitted by shifting a carrier
frequency between two preset
frequencies. This type of transmission is
called Frequency Shift Keying (FSK)
technique.
Fig: FSK Generator
Contd…..
57. FSK Generator
57
The frequency of the output wave form given by,
C
R
R
f O
)
45
.
1
2
( 1 2
+
=
When input digital is LOW, Q1 is ON then R3 parallel R1
C
R
R
R
f O
)
45
.
1
2
||
( 3 1 2
+
=
➢ A 555 timer is astable mode can be used to generate FSK signal.
➢ When input digital data is HIGH, T1 is OFF & 555 timer works as normal astable
multivibrator.
58. 2. Pulse Position Modulator
58
Fig (a): Pulse position Modulator
Fig (b): Output Wave Form of PPM
Description:
➢ The pulse position modulator can be constructed
by applying a modulating signal to pin 5 of a 555
timer connected for astable operation.
➢ The output pulse position varies with the
modulating signal, since the threshold voltage
and hence the time delay is varied.
➢ The output waveform that the frequency is
varying leading to pulse position modulation.
59. Astable Multivibrator
59
Problem:
In the astable multivibrator of fig, RA=2.2KΩ, RB=3.9K Ω and C=0.1µF. Determine
the positive pulse width tH, negative pulse width tLow, and free-running frequency fo.
Solution:
ms
X
K
C
R
t B
LOW
269
.
0
)
1
.
0
)(
9
.
3
(
69
.
0
69
.
0 10
6
=
=
= −
?
)
45
.
1
1
2
(
=
=
=
+ C
T R
R
f
A B
o
ms
X
K
K
C
R
R
t B
A
HIGH
421
.
0
)
1
.
0
)(
9
.
3
2
.
2
(
69
.
0
)
(
69
.
0 10
6
=
+
=
+
= −
?
100
9
.
3
2
2
.
2
9
.
3
2
.
2
100
)
)
100
%
2
(
(
=
+
+
=
=
=
+
+
X
K
X
K
K
X
X
T
D
R
R
R
R
t
A
A
B
B
HIGH
Duty Cycle,
?
100
9
.
3
2
2
.
2
9
.
3
100
)
100
%
2
(
=
+
=
=
=
+
X
K
X
K
X
X
T
D
R
R
R
t
A B
B
LOW
60. 60
One Possible
Solution:
One Possible
Solution:
Example: A 555 oscillator can be combined with a J-K FF to
produce a 50% duty-cycle signal. Modify the above
circuit to achieve a 50% duty-cycle, 40 KHz signal.
Example: Design a 555 Oscillator to produce an approximate
square-wave at 40 KHz. Let C > 470 pF.
F=40KHz; T=25µs; t1=t2=12.5µs
For a square-wave RA<<RB; Let RA=1K and RB=10K
t1=0.693(RB)(C); 12.5µs=0.693(10K)(C); C=1800pF
T=0.693(RA+2RB)C: T=0.693(1K+20K)1800pF
T=26.2µs; F=1/T; F=38KHz (almost square-wave).
Reduce by half the 1800pF. This will create a T=13.1µs or F=76.35 KHz
(almost square-wave). Now, take the output of the 555 Timer and connect
it to the CLK input of a J-K FF wired in the toggle mode (J and K inputs
connected to +5V). The result at the Q output of the J-K FF is a perfect
38.17 KHz square-wave.
61. Comparison of Multivibrator Circuits
61
Monostable Multivibrator Astable Multivibrator
1. It has only one stable state 1. There is no stable state.
2. Trigger is required for the operation
to change the state.
2. Trigger is not required to change the
state hence called free running.
3. Two comparators R and C are
necessary with IC 555 to obtain the
circuit.
3. Three components RA, RB and C are
necessary with IC 555 to obtain the
circuit.
4. The pulse width is given by T=1.1RC
Seconds
4. The frequency is given by,
5. The frequency of operation is
controlled by frequency of trigger
pulses applied.
5. The frequency of operation is
controlled by RA, RB & C.
6. The applications are timer, frequency
divider, pulse width modulation etc…
6. The applications are square wave
generator, flasher, voltage controlled
oscillator, FSK Generator etc..
C
T R
R
f
A B
o
)
45
.
1
1
2
( +
=
=
62. Schmitt Trigger
62
The use of 555 timer as a Schmitt trigger is shown in fig.
Here the two internal comparators are tied together and externally
biased at Vcc/2 through R1 and R2. Since the upper comparator will
trip at 2Vcc/3 and lower comparator at Vcc/3, the bias provided by R1
and R2 is centered within these two thresholds.
Fig (b): Output Wave Form
Fig (a): Circuit Diagram of Schmitt Trigger
63. Features of IC 555 Timer
The Features of IC 555 Timer are:
1. The 555 is a monolithic timer device which can be used
to produce accurate and highly stable time delays or oscillation. It
can be used to produce time delays ranging from few
microseconds to several hours.
2. It has two basic operating modes: monostable and
astable.
3. It is available in three packages: 8-pin metal can, 8-pin
mini DIP or a 14-pin. A 14-pin package is IC 556 which consists of
two 555 times.
63
64. Features of IC 555 Timer
4. The NE 555( signetics ) can operate with a supply
voltage in the range of 4.5v to 18v and output currents of
200mA.
5. It has a very high temperature stability, as it is
designed to operate in the temperature range of -55⁰c to
125oc.
6. Its output is compatible with TTL, CMOS and Op-
Amp circuits.
64
66. PHASE-LOCKED LOOPS- Introduction
66
The phase-locked loop is a negative feedback system in
which the frequency of an internal oscillator (vco) is
matched to the frequency of an external waveform with
some Pre-defined phase difference.
Vd(t)
PHASE
COMPARATOR
(PC)
LOW PASS
FILTER
(LPF)
VCO
AMPLIFIER
(A)
Vi(t)
Vo(t)
Vp(t)
(EXTERNAL R & C DETERMINES
VCO FREQUENCY)
v
f
Ko
=
Contd…..
67. PHASE-LOCKED LOOPS
67
Contd…..
• The phase comparator (phase detector) can be as simple as
an exclusive-or gate (digital signals) or is a mixer (non-linear
device - frequency multiplier) for analog signals.
• The phase comparator generates an output voltage Vp(t) (relates
to the phase difference between external signal Vi(t) and vco
output Vo(t) ).
• If the two frequencies are the same (with a pre-defined phase
difference) then Vp(t) = 0.
• If the two frequencies are not equal (with various phase
differences), then Vp(t) = 0 and with frequency components
about twice the input frequency.
Phase Comparator:
68. PHASE-LOCKED LOOPS
68
Contd…..
• The low pass filter removes these high frequency components and
Vd(t) is a variable dc voltage which is a function of the phase
difference.
Voltage Controlled Oscillator:
• The vco has a free-running frequency, fo, approximately equal to
the input frequency. the vco frequency varies as a function of Vd(t)
• The feedback loop tries to adjust the vco frequency so that:
Vi(t) FREQUENCY = Vo(t) FREQUENCY
THE VCO IS SYNCHRONIZED, OR LOCKED TO Vi(t)
Low pass filter:
69. PLL LOCK RANGE
69
• Lock range is defined as the range of frequencies in the vicinity of
the vco’s Natural frequency (free-running frequency) for which the
pll can maintain lock with the input signal. The lock range is also
called the tracking Range.
• The lock range is a function of the transfer functions of the pc,
amplifier, and vco.
Hold-in range:
•The hold-in range is equal to half the lock range
•The lowest frequency that the pll will track is called the lower lock
limit. The highest frequency that the pll will track is called the upper
lock limit Contd…..
Lock range:
71. PLL CAPTURE RANGE
71
Contd….
• Capture range is defined as the band of frequencies in the vicinity
of fo where the pll can establish or acquire lock with an input range
(also called the acquisition range).
• Capture range is a function of the BW of the lpf ( lpf BW capture
range).
• Capture range is between 1.1 and 1.7 times the natural frequency
of the vco.
The pull-in range:
•The pull-in range is equal to half the capture range
• The lowest frequency that the pll can lock onto is called the lower
capture limit
CAPTURE RANGE:
72. PLL CAPTURE RANGE
• The highest frequency that the pll can lock onto is called
the upper capture limit
72
74. PLL-Basic Components
74
Phase detector:
➢ Transfer function: KΦ [V/radians].
➢ Implemented as: four quad
multiplier, XOR gate, state
machine.
Voltage controlled oscillator (VCO):
➢ Frequency is the first derivative of
phase.
➢ Transfer function: KVCO/s
[radians/(V•s)]
Low pass filter:
➢ Removes high frequency components coming from the phase detector.
➢ Determines loop order and loop dynamics.
75. PLL OPERATION-Putting All Together
75
e
d
d
V
K
=
e
d
d K
V
= d
a
f
out V
K
K
V =
a
f
out
d
K
K
V
V =
d
d
e
K
V
=
v
f
Ko
=
o
out
K
f
V
=
out
o
V
f
K
=
o
out K
V
f =
n
in f
f
f −
=
o
a
f
d
L K
K
K
K
K =
OPEN-LOOP GAIN:
78. PLL- Example
78
Problem:
fn = 200 kHz, fi = 210 kHz, Kd = 0.2 V/rad, Kf = 1, Ka = 5, Ko = 20 kHz/V
rad
kHz
KL /
20
)
20
)(
5
)(
1
)(
2
(. =
=
PLL OPEN-LOOP GAIN:
VCO FREQUENCY CHANGE for LOCK:
kHz
f
f
f n
in 10
200
210 =
−
=
−
=
PLL OUTPUT VOLTAGE:
V
V
kHz
kHz
K
f
V
o
out 5
.
/
20
10
=
=
=
Solution:
Contd…..
79. PLL-Example
79
STATIC PHASE ERROR:
=
=
=
= 65
.
28
5
.
/
2
.
1
.
rad
rad
V
V
K
V
e
d
d
HOLD-IN RANGE:
LOCK RANGE:
kHz
K
f L 4
.
31
2
max
=
=
kHz
f
Range
Lock 8
.
62
2 max
=
=
PHASE DETECTOR OUTPUT VOLTAGE:
V
K
K
V
V
a
f
out
d 1
.
)
5
(
1
5
.
=
=
=
80. Salient Features of 565 PLL
1. Operating frequency range =0.01Hz to 500KHz
2. Operating voltage range = ±6v to ± 12v
3. Input level required for tracking:
10mv rms min to 3v peak to peak max
4. Input impedance = 10kΩ typically.
5. Output sink current : 1mA typically.
6. Output source current: 10mA typically
7. Drift in VCO Centre frequency: 300 PPM/ ⁰c
8. Drift in VCO Centre frequency with supply voltage: 1.5
percent/Vmax
9. Triangle wave amplitude: 2.4 Vpp at ± 6v supply voltage.
10. Square wave amplitude: 5.4 Vpp at ± 6v supply voltage.
11. Bandwidth adjustment range: < ± 1 to ± 60%
80
81. PLL APPLICATIONS
81
• Analog and digital modulation
• Frequency shift keying (fsk) decoders
• Am modulation / demodulation
• Fm modulation / demodulation
• Frequency synthesis
• Frequency generation
83. Voltage Controlled Oscillator (VCO)
83
A voltage controlled oscillator is an oscillator circuit
in which the frequency of oscillations can be
controlled by an externally applied voltage
88. Applications of VCO
88
The various applications of VCO are:
1. Frequency Modulation.
2. Signal Generation (Triangular or Square Wave)
3. Function Generation.
4. Frequency Shift Keying i.e. FSK demodulator.
5. In frequency multipliers.
6. Tone Generation.