Prabhu Mike

ELECTRONIC DEVICES & CIRCUITS

R. Prabhu13291225-02-2015

2/25/2015

Prabhu Mike

LIGHT EMITTING DIODE (LED)

• LED is a specially made forward biased PN junction diode, which emits light when current flows through it.•CONSTRUCTION: In this diode a P-type semi-conductive material is deposited on the N-type substrate layer by using diffusion method.

2/25/2015

Prabhu Mike

Cont…

2/25/2015

Prabhu Mike

Cont….

• The colour of the light emits from the diode depending upon the type of material used, as given below.

(1) GaAs : Infrared radiation (2) GaP : Red or green light (3) GaAsP : Red or yellow light

2/25/2015

Prabhu Mike

Characteristics

2/25/2015

Prabhu Mike

Applications

• Used in ON and OFF indicators.• Used in optical communications.• Used in 7 segment and 14 segment displays.• Used in optical switching applications.

2/25/2015

Prabhu Mike

SEVEN SEGMENT LED DISPLAY

• It contains seven rectangular LEDs. Each LED is called a segment because it forms a part of the character being displayed.

• There are two possible connections in seven segment displays. They are

1. common anode type(+ve) 2. common cathode type(GND)

2/25/2015

Prabhu Mike

7-segment LED

2/25/2015

Prabhu Mike

ComparisonS.NO LED LCD1. • Consumes more power • Consumes less power

2. • Life time is more • Life time is low

3. • It emits light when energised • It will not emit or generate light.

4. • Red, Green, Yellow colour lights are found, depends upon the materials used.

• It is found only in monochrome in nature.

2/25/2015

Prabhu Mike

SOLAR CELL

• A Solar cell or solar battery is also a PN junction diode. It converts solar energy into electrical energy. It is also called solar energy converter.

• Construction: A solar cell is made up of Germanium (Ge)

or Silicon (Si) materials.

2/25/2015

Prabhu Mike

Construction

2/25/2015

Prabhu Mike

Characteristics

2/25/2015

Prabhu Mike

Applications

• Used in power sources in satellites.• Used to charge storage batteries.• Used as solar heater, cooker etc……

2/25/2015

Prabhu Mike

Thank you

2/25/2015