The document discusses the 555 timer integrated circuit, which is commonly used to generate clock pulses or time delays in electronic circuits. It describes the internal components of the 555 timer, including two comparators, a flip-flop, and three resistors that create a voltage divider. The 555 timer can operate in astable or monostable modes to produce oscillating or single output pulses using external resistors and capacitors. Formulas are provided to calculate the frequency, period, and duty cycle in astable mode and the time delay in monostable mode.

1. 555 TIMER
THE MOST
VERSATILE IC USED
IN ELECTRONICS
CIRCUITS
ELECTROKRITI
V6.0 INNOVATE TO IMPLEMENT…TEAM EHC

2. WHAT IS 555 TIMER
IT IS A 8 PIN IC.
GENERALLY USED TO GENERATE
CLOCK
PULSE OF WIDE RANGE OF
FREQUENCY
CAN BE ALSO USED TO GENERATE
SPECIFIC TIME DELAY
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3. INSIDE 555
TIMER
-
+
-
+
RESET
SET
Q
Q
COMP1
COMP2
Flip-Flop
3 RESISTORS OF 5K
2 COMPARATORS
S-R FLIP FLOP
TRANSISTOR
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4. COMPARATOR
-
+
V1
V2
VOUT
IF V1>V2 THEN VOUT = -
VSAT
IF V1<V2 THEN VOUT =
+VSAT
+VSA
T
-VSAT
-
+
-
+
RESET
SET
Q
Q
COMP1
COMP2
Flip-Flop
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5. 3 RESISTORS
VCC
0.66 VCC
0.33 VCC
USED AS VOLTAGE
DIVIDER NETWORK
GIVES THE
REFERENCE
VOLTAGE TO THE
COMPARATORS
-
+
-
+
RESET
SET
Q
Q
COMP1
COMP2
Flip-Flop
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6. S-R FLIP FLOP
RESET
SET Q
Flip-Flop
Q
S R Q Q’
0 0 HOLD
1 0 1 0
0 1 0 1
-
+
-
+
RESET
SET
Q
Q
COMP1
COMP2
Flip-Flop
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7. TRANSISTOR
A
B
VI
N
C
E
VI
N
USED AS A SWITCH
IF VIN=1 THEN C-E IS SHORTED
IF VIN=0 THEN C-E IS OPEN
CKT
-
+
-
+
RESET
SET
Q
Q
COMP1
COMP2
Flip-Flop
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8. PIN
CONFIGURATION
Control Voltage (5)
Threshold Voltage (6)
Trigger Voltage (2)
Ground (1)
Vcc (8) Discharge (7)
Reset (4)
Output (3)
-
+
-
+
RESET
SET
Q
Q
COMP1
COMP2
Flip-Flop
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9. MODE OF
OPERATION
MONOSTABLE MODE
ASTABLE MODE
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10. ASTABLE
MODE
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8
5
6
2
1 4
3
7

11. ASTABLE MODE
CALCULATION
TIME PERIOD
 TON=0.693(RA+RB)C
 TOFF=0.693RBC
 TTOT=0.693(RA+2RB)C
CAN YOU CALCULATE THE FREQUENCY
AND DUTY CYCLE OF THE ASTABLE MODE ?
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12. MONOSTABLE
CALCULATION
 T =
1.1RC
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13. MONOSTABLE
MODE
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8
5
6
2
1 4
3
7

14. LETS MAKE
IT
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