MINI

PROJECT
REPORT

JD COLLEGE OF
ENGINEERING

IC555 TIMER
CIRCUIT
 A
Project Report
On

“IC 555 TIMER CIRCUIT”

A REPORT SUBMITTED TO J D COLLEGE OF ENGINEERING AND TECHNOLOGY
NAGPUR IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
AWARD OF
“ELECTROTECH-2010”

SUBMITTED BY

PRAKASH CHOWDHARY SAURABH BHOLE

ANIKET CHAUDHARI
( 5th sem. ETC)

UNDER THE GUIDANCE OF

Mr. Umale Sir

Department of Electronics Engineering

DEPARTMENT OF ELECTRONICS ENGINEERING

J D COLLEGE OF ENGINEERING AND TECHOLOGY, NAGPUR 1
 CERTIFICATE

This is to certify that the dissertation entitled “IC 555 TIMER

CIRCUIT” which has been duly submitted by the following students of
third year (5th Semester) in recognition towards partial fulfillment for the
award of “ELECTROTECH-2010” In Electronics & Telecommunication
Engineering (EC), J D College of Engineering & Technology,Nagpur.

Submitted By

PRAKASH CHOWDHARY SAURABH BHOLE

ANIKET CHAUDHARI
(ETC 5TH SEM)

___________________________
MR. UMALE SIR,
PROJECT GUIDE

__________________________ _____________________
PROF. MRS. A. A. KHURSHID PROF. DR. P. B. PATIL
H.O.D, ELECTRONICS ENGG. PRINCIPAL,
DEPARTMENT JDCOE, NAGPUR
JDCOE, NAGPUR.
2
 DECLARATION

We the students of third year Electronics & Telecommunication

Engineering (EC) humbly declare that we have completed the project work

as described in this report by our own skill and during summer vacation

2010 as per the instructions and guidance of Mr. UMALE.

Further we declare that no part of this project is duplicated from any

other literature in contravention of the academic ethics.

PROJECTEES SIGNATURE

Aniket A. Chaudhari _________________________

Saurabh S. Bhole _________________________

Prakash A. Chowdhar y __________________________

ACKNOWLEDGEMENT
 “No man is indispensable, but there are certain mortal without whom quality of
work suffers. Their guidance becomes indispensable in acquiring quality results”.

With deepest sense of esteem and gratitude, we express my sincere thanks to my

project guide Prof. MR. UMALE, under whose guidance I was able to learn much
more and to complete successfully my dissertation work most efficiently.

We are thankful to Prof. MRS. A. A. KHURSHID, Head and Prof. Electronics

Engineering Department, for his inspiration and encouragement. She has immensely
helped in providing all opportunities and facilities for the dissertation work.

We could not forget to express my sincere thanks to Prof. Dr. P. B. PATIL,

Principal, for providing institutional facilities and giving timely suggestions.
.
We are also thankful to all the faculty members of department who helped us,
directly or indirectly. My thanks are due to all those who have shown keen interest in this
work and provided much encouragement.

PROJECTEES

ANIKET CHAUDHARI
SAURABH BHOLE
PRAKASH CHOWDHARY

4
Introduction
 Today’s world is a digital one. Everyone wants the world to be
faster. Digital technology is the need of the hour. It has widespread
application in various fields.
TIMER FLASH is one of the basic application that the digital
world is aware of. The 555 Timer IC is an integrated circuit (chip)
implementing a variety of timer and multivibrator applications.
The IC was designed by Hans R. Camenzind in 1970 and brought
to market in 1971 by Signetics (later acquired by Philips). The
original name was the SE555 (metal can) / (plastic DIP) and the
part was described as "The IC Time Machine"., the standard 555
package includes over 20 transistors, 2 diodes and 15 resistors on a
silicon chip installed in an 8-pin mini dual-in-line package.
The 8-pin 555 timer must be one of the most useful ICs ever
made and it is used in many projects. With just a few external
components it can be used to build many circuits, not all of them
involve timing!
The IC555 monolithic timing circuit is a highly stable Controller
capable of producing accurate time delays or oscillation.In the time
delay mode of operation,The time is precisely controlled by one
external resistor and capacitor.
For astable operation as an oscillator,The free running frequency
and the duty cycle are both accurately controlled with two external
Resistors and one capacitor.The circuit may be triggered and reset
on falling waveforms, and the output Structure can source or sink
up to 200mA.The IC555 is available in plastic and ceramic minidip
Package and in a 8-leadmicropackage and in metal Can package
version.

Circuit Diagram
Internal Layout of IC 555

Components Required
 ¶ Ic 555
¶ 2 Light Emitting Diodes
¶ Resistor - 470 Ω
¶ Resistor - 470 Ω
¶ Variable Resistor (Preset) - 222 KΩ
¶ Resistor - 1 KΩ
¶ Resistor - 1KΩ
¶ Capacitor - 10 µF
¶ Capacitor - 100 µF

Data Sheet

Timers and signal generators

Order code Manufacturer code Description

77-1212 n/a n/a

82-0336 NE555 NE555 SINGLE TIMER

(RC)

82-0338 NE555D NE555D SINGLE TIMER

(SMD) (RC)

Order Codes
Part Temperature Package
Number Range
N D

NE555 0°C, 70°C  

SA 555 –40°C, 105°C  
SE 555 –55°C, 125°C  

Absolute Maximum Ratings

Symbol Parameter Value Unit

Vcc Supply Voltage 18 V

Toper Operating free air

temp. range for
NE555 0 to 70 °C
SA555 -40 to 105
SE555 -55 to 125
Tj Junction 150 °C
Temperature
Tstg Storage Temperature -65 to 150 °C
Range

ELECTRICAL CHARACTERISTICS
Tamb = +25oC, VCC = +5V to +15V (unless otherwise specified)

Symbol Parameter SE555 SA555-NE555 Unit

Min. Type Max. Min. Type Max.
Icc Supply Current 3 5 3 6
(RL 8) (- note 10 12 10 15 mA
1) 2 2
Low State
VCC = +5V
VCC = +15V
High State
VCC = 5V
Timing Error 0.5 2 1 3 %
(monostable) 30 100 50 0.5 ppm/°C
(RA = 2k to 0.05 0.2 0.1 %/V
100kW, C =
0.1mF)
Initial
Accuracy -
(note 2)
Drift with
Temperature
Drift with
Supply
Voltage
Timing Error 1.5 2.25 %
(astable) 90 150 ppm/°C
(RA, RB = 0.15 0.3 %/V
1kW to
100kW, C =
0.1mF,
VCC = +15V)
Initial
Accuracy -
(note 2)
Drift with
Temperature
Drift with
Supply
Voltage
VCL Control 9.6 10 10.4 9 10 11 V
Voltage level 2.9 3.33 3.8 2.6 3.33 4
VCC = +15V
VCC = +5V
Vth Threshold 9.4 10 10.6 8.8 10 11.2 V
Voltage 2.7 3.33 4 2.4 3.33 4.2
VCC = +15V
VCC = +5V
Ith Threshold 0.1 0.25 0.1 0.25 mA
Current - (note
 3)

Vtrig Trigger 4.8 5 5.2 4.5 5 5.6 V

Voltage 1.45 1.67 1.9 1.1 1.67 2.2
VCC = +15V
VCC = +5V
Itrig Trigger 0.5 0.9 0.5 2.0 mA
Current (Vtrig
= 0V)
Vreset Reset Voltage 0.4 0.7 1 0.4 0.7 1 V
- (note 4)
VOL Low Level 0.1 0.15 0.1 0.25 V
Output 0.4 0.5 0.4 0.75
Voltage 2 2.2 2 2.5
VCC = +15V, 2.5 2.5
IO(sink) = 0.1 0.25 0.3 0.4
10mA 0.05 0.2 0.25 0.35
IO(sink) =
50mA
IO(sink) =
100mA
IO(sink) =
200mA
VCC = +5V,
IO(sink) =
8mA
IO(sink) =
5mA
VOH High Level 12.5 12.5 V
Output 13 13.3 12.7 13.3
Voltage 3 3.3 5 3.3
VCC = +15V, 2.75
IO(source) =
200mA
IO(source) =
100mA
VCC = +5V,
IO(source) =
100mA
Notes : 1. Supply current when output is high is typically 1mA less.
2. Tested at VCC = +5V and VCC = +15V.
3. This will determine the maximum value of RA + RB for +15V operation the max total is R = 20MΩ and for 5V operation,
the max total R = 3.5MΩ .

Advantages
¶ LOW TURN OFF TIME

¶ MAXIMUM OPERATING FREQUENCYGREATERTHAN 500kHz

¶ TIMING FROM MICRO SECONDS TO HOURS

¶ OPERATES IN BOTH ASTABLE AND MONOSTABLE MODES

¶ HIGH OUTPUT CURRENT CAN SOURCE OR SINK 200mA

¶ ADJUSTABLE DUTY CYCLE

¶ TTL COMPATIBLE

¶ TEMPERATURE STABILITY OF 0.005% PER °C

Graphs
Minimum Pulse Width Required for Triggering

Supply Current versus Supply Voltage

 Delay Time versus Supply Voltage

Propagation Delay versus Voltage Level of Trigger Value

IC 555 Configurations
We all know how versatile the IC 555 is and regarding its wide range of
applications. Basically the IC 555 can be operated in two most commonly
used modes viz. monostable and astable multivibrator.

In the monostable mode the output at pin 3 of the IC goes high in

response to an external applied trigger at its pin 2. The output holds this
position for a time period determined by the values of its timing components
consisting of a resistor and a capacitor.

The best example of this mode of operation of the IC can be studied in

one of my previous article on a frequency meter. But the most common
application of this mode of operation is in a 555 timer circuit, where the IC
is used to switch ON a load at its output for the set period of time after
which it is automatically switched OFF.

In the astable mode configuration the IC continuously produces pulses at

its output. These pulses are normally square waves and its frequency can be
adjusted again by varying the timing components comprising of a resistor
and a capacitor.
Working of Circuit

As shown in the figure the IC 555 is configured as a monostable

mutivibrator. On pressing the switch S1, a momentary logic high appears at
pin 2 of the IC and its output at pin 3 goes high switching ON the relay and
the load connected to the relay contacts. The output will sustain the position
till its timing capacitor C1 gets fully discharged through the variable resistor
VR1. The value of this resistor may be varied to get the desirable time
delays. The delay may be calculated using the below given formula:

T = 1.1 × (VR1 + R1+R2) × C1

Schematic of a 555 in monostable mode

The relationships of the trigger signal, the voltage on C and the pulse
width in monostable mode. In the monostable mode, the 555 timer acts as a
“one-shot” pulse generator. The pulse begins when the 555 timer receives a
trigger signal. The width of the pulse is determined by the time constant of
an RC network, which consists of a capacitor (C) and a resistor (R). The
pulse ends when the charge on the C equals 2/3 of the supply voltage. The
pulse width can be lengthened or shortened to the need of the specific
application by adjusting the values of R and C.The pulse width of time t,
which is the time it takes to charge C to 2/3 of the supply voltage, is given
by

T = 1.1 × (VR1 + R1+R2) × C1

where t is in seconds, R is in ohms and C is in farads. See RC circuit for an

explanation of this effect.
 INDEX

Sr.No. Perticulars

1. Introduction
2. Components Required
3. Circuit Diagram
4. Circuit Explanation
5. IC 555 Configuration
6. Applications & Future Scope
7. Advantages
8. Data Sheet
9. References
References
 http://www.brighthub.com/engineering/electrical/articles/
68119.aspx#ixzz0mMestoXE

 Wikipedia

 www.scribd.com

Applications
Monostable Mode
In this mode, the 555 functions as a "one-shot".
@ Timers
@ Missing pulse detection
@ Bounce-free switches
@ Touch switches
@ Frequency divider
@ Capacitance measurement
@ Pulse-width modulation (PWM) etc.
Astable Mode
Free running mode: the 555 can operate as an oscillator
@LED and lamp flashers
@ Pulse generation
@Logic clocks
@Tone generation
@ Security alarms
@Pulse position modulation etc.
Bistable Mode
555 can operate as a flip-flop, if the DIS pin is not connected and no
capacitor is used.
@ bounce-free latched switches
 MINI-
PROJECT
IC 555 TIMER CIRCUIT