PPT: Function Generator & 555 Timer | Analog Circuits - Electronics and Communication Engineering (ECE) PDF Download

 Page 1


555 TIMER IC
Page 2


555 TIMER IC
INTRODUCTION
• The 555 IC was designed in 1971 by Hans 
Camenzind under contract to SigNetics 
Corporation.
• Basically, 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.
Page 3


555 TIMER IC
INTRODUCTION
• The 555 IC was designed in 1971 by Hans 
Camenzind under contract to SigNetics 
Corporation.
• Basically, 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.
Pin Configuration
The function of each pin of the IC is given below –
•Pin –1: Ground
•Pin –2: Trigger
•Pin –3: Output
•Pin –4: Reset
•Pin –5: Control Voltage
•Pin –6: Threshold
•Pin –7: Discharge
•Pin –8: Vcc
Page 4


555 TIMER IC
INTRODUCTION
• The 555 IC was designed in 1971 by Hans 
Camenzind under contract to SigNetics 
Corporation.
• Basically, 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.
Pin Configuration
The function of each pin of the IC is given below –
•Pin –1: Ground
•Pin –2: Trigger
•Pin –3: Output
•Pin –4: Reset
•Pin –5: Control Voltage
•Pin –6: Threshold
•Pin –7: Discharge
•Pin –8: Vcc
Functional diagram of 555 timer
Threshold
+ 
R
-
(2/3)Vcc
Threshold > (2/3)Vcc =>R=logic ‘1’
Threshold < (2/3)Vcc =>R=logic ‘ 0 ’
(1/3)Vcc
+ 
S
-
Trigger
Trigger<(1/3)Vcc =>S=logic ‘1’
Trigger>(1/3)Vcc =>S=logic ‘ 0 ’
R S Q- Q
0 0
Previous state
0 1 0 1
1 0 1 0
1 1 X X
Page 5


555 TIMER IC
INTRODUCTION
• The 555 IC was designed in 1971 by Hans 
Camenzind under contract to SigNetics 
Corporation.
• Basically, 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.
Pin Configuration
The function of each pin of the IC is given below –
•Pin –1: Ground
•Pin –2: Trigger
•Pin –3: Output
•Pin –4: Reset
•Pin –5: Control Voltage
•Pin –6: Threshold
•Pin –7: Discharge
•Pin –8: Vcc
Functional diagram of 555 timer
Threshold
+ 
R
-
(2/3)Vcc
Threshold > (2/3)Vcc =>R=logic ‘1’
Threshold < (2/3)Vcc =>R=logic ‘ 0 ’
(1/3)Vcc
+ 
S
-
Trigger
Trigger<(1/3)Vcc =>S=logic ‘1’
Trigger>(1/3)Vcc =>S=logic ‘ 0 ’
R S Q- Q
0 0
Previous state
0 1 0 1
1 0 1 0
1 1 X X
Modes of Operation
555 IC Timer applications can be classified into two main categories:
1. Monostable Multivibrators : Producing a single pulse when
triggered.
2. Astable Multivibrators : Producing a square wave.