555 TIMER

THE MOST VERSATILE IC

USED IN ELECTRONICS

CIRCUITSELECTROKRITI V6.0INNOVATE TO IMPLEMENT…TEAM EHC

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 DELAYTEAM EHC

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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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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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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S-R FLIP FLOP

RESET

SET Q

Flip-Flop

Q

S R Q Q’0 0 HOL

D

1 0 1 0

0 1 0 1

-

+-

+

RESET

SET

Q

Q

COMP1

COMP2

Flip-Flop

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TRANSISTORA

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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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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MODE OF OPERATION

MONOSTABLE MODE

ASTABLE MODE

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ASTABLE MODE

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8

5

6

2

1 4

3

7

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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MONOSTABLE CALCULATION

T = 1.1RC

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MONOSTABLE MODE

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8

5

6

2

1 4

3

7

LETS MAKE IT

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