555 Timer IC: Introduction, Working and Pin configuration

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One of the most versatile linear integrated circuit is 555 timer. 555 timer IC was first introduced in early 1970 by  Signetics Corporation.555 timer IC is incredibly low cost and popular timing IC that is used by electronics student, hobbyist for generating timing delay and pulses. Mono stabale and astable multi vibrators is that the most correct example of its application. With the exception of this it's conjointly used for oscillations, waveform generators, analog frequency meters, voltage regulators, digital  probes, tone generation, frequency divider and lots of others.This device is obtainable as 8-pin mini Dual-in-line package(DIP)  or 14 pin Dual-in-line package(DIP) that consist 25 transistor,16 resistors, 2 diode.

PIN CONFIGURATION OF 555 TIMER IC
555 timer ic pin configuration
8-Pin DIP 555 Timer IC

Pin 1: Ground   This pin is used to measured the all voltages.

Pin 2: Trigger   Negative going pulse is applied to this pin whose dc level is greater than 1/3 times                                VCC. Thus comparator 2 output goes low. The output remains high as long as                                      trigger terminal is held at low voltage.

Pin 3: Output    Output pin is available to connect the load.There are two ways of connecting the                                   load either between pin 3 and ground or between pin 3 and +Vcc pin of 555 timer                                 IC.

Pin 4: Reset      555 timer can be reset by applying a negative pulse to this pin.

Pin 5: control voltage  To change the threshold voltage and trigger voltage an external voltage is                                               applied to this pin.

Pin 6: Threshold  SR flip flop is reset when voltage at this pin is greater than 2/3 Vcc.

Pin 7: Discharge   This pin is directly connected to the collector of transistor.When transistor is off                                     this acts as a open circuit and when transistor is on, acts as a shot circuit.

Pin 8:   A Supply voltage is applied to this pin that ranges from +5v to +18v with respect to                              the ground.

Block Diagram of 555 Timer IC

555 timer ic block diagram image
555 Timer IC Block Diagram

The 555 timer IC work as a mono-stable multi-vibrator and astable multi-vibrator. A voltage divider circuit is internally connected to the Pin 8 and Pin 1 of 555 timer IC. This circuit hold positive non inverting terminal of comparator at 1/3Vcc and negative inverting terminal of comparator at 2/3Vcc. The output from each comparator is connected to the input of the SR Flip-Flop. The output from the SR Flip-flop acts as a switching stage to drive the Load.

555 Timer IC has three operative modes known as:
1: Monostable
2: Astable
3: Bistable

To Know additional concerning 555 IC Click on this 555 Data sheet.

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