1

GRAPHIC ERAUNIVERSITYTRANSFORMING DREAMS IN TO REALITY

PRESENTED BY :- ANKIT SINGHSECTION :- JB.TECH M.E

DIODE APPLICATONS

2

What is diode ?

In electronics, a diode is a two terminal electronic component with asymmetric conductance; it has low (ideally zero) resistance to current in one direction, and high (ideally infinite) resistance in the other.

3

P-N junction diode ZENER diode LIGHT EMITTING diode PHOTO diode

TYPES OF SEMICONDUCTOR

DIODE

etc.

4

REPRESENTATION OF

DIODES P-N junction diode

PHOTO diode

LIGHT EMITTING diode

ZENER diode

5

A p–n junction diode is made of a crystal of semiconductor, usually silicon,

but germanium and gallium arsenide are also used.

Impurities are added to it to create a region on one side that contains negative charge carriers (electrons), called n-type semiconductor, and a region on the other side that contains positive charge carriers (holes), called p-type semiconductor.

When two materials i.e. n-type and p-type are attached together, a momentary flow of electrons occur from n to p side resulting in a third region where no charge carriers are present.

P-N JUNCTION DIODE

6

ZERO BIAS – no potential is applied FORWARD BIAS- when p-type is connected

with +terminal and n-type is connected with –terminal of the source

REVERSE BIAS-when p-type is connected with –terminal and n-type is connected with +terminal of the source

WORKING OF P-N JUNCTION DIODE

IN

7

CHARACTERISTICCURVE

• FORWARD BIAS•REVERSE BIAS

8

HALF WAVE RECTIFIER FULL WAVE RECTIFIER 1- CENTER TAP FULL WAVE RECTIFIER 2-BRIDGE RECTIFIER

APPLICATIONOF

P-N JUNCTION DIODE

9

HALF WAVE RECTIFIER

A simple Half Wave Rectifier is nothing more than a single pn junction diode connected in series to the load resistor. If you look at the above diagram, we are giving an alternating current as input. Input voltage is given to a step down transformer and the resulting reduced output of transformer is given to the diode ‘D’ and load resistor RL. The output voltage is measured across load resistor RL.

10

•In this simplified (ideal diode) case the input and output waveforms are as shown

The diode must withstand a peak inverse voltage of V M

11

The average d.c. value of this half-wave-rectified sine wave is

0

0sin2

1dVV MAV

MM VV 0coscos

2

12

•So far this rectifier is not very useful.

•Even though the output does not change polarity it has a lot of ripple, i.e. variations in output voltage about a steady value.

HALF WAVE RECTIFIRE

13

A full-wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output. Full-wave rectification converts both polarities of the input waveform to pulsating DC (direct current), and yields a higher average output voltage. 

FULL WAVE RECTIFIER

14

The average and root-mean-square no-load output voltages of an ideal single-phase full-wave rectifier are:

ww

15

BRIDGE RECTIFIER

As shown in the given diagram of full wave bridge rectifier it consists of four diodes under the condition in which four diodes are connected the called bridge circuit. So due to this type of circuit is named bridge rectifier. A resistor is connected in the circuit whiere rectified output voltage appears called load resistor RL

16

The four diodes labelled D1 to D4 are arranged in “series pairs” with only two diodes conducting current during each half cycle. During the positive half cycle of the supply, diodes D1 and D2conduct in series while diodes D3 and D4 are reverse biased and the current flows through the load as shown above.

17

ZENER DIODE

•A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode, but also permits it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, "Zener knee voltage", "Zener voltage", "avalanche point", or "peak inverse voltage".

18

19

APPLICATION OF ZENEDIODE

A)Line Regulation  In this type of regulation, series resistance and load resistance are Fixed, only input voltage is changing. Output voltage remains the same as long as the input voltage is maintained above a minimum value.Percentage of line regulation can be calculated by =                        where V0 is the output voltage and VIN is the input voltage and  ΔV0 is the change in output voltage for a particular change in input voltage ΔVIN.

20

 

b) Load Regulation In this type of regulation, input voltage is fixed and the load resistance is varying. Output volt remains same, as long as the load resistance is maintained above a minimum value.                        

21

LIGHT EMITTING DIODE•A light-emitting diode (LED) is a two-lead semiconductor light source.

•It is a basic pn-junction diode, which emits light when activated. When a fitting voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons.

•This effect is called electroluminescence, and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor.

22

INDICATOR AND SIGNS LIGHTING Data communication and other

signaling Light sources for machine vision

systems Energy consumption

APPLCATIONS OFLED

23

LED USES

DISPLAY BOARDS TRAFFIC LIGHTS DAY TIME RUNNING LIGHTS

LED panel light source used in an experiment on plant growth

24

ANY QUESTIONS ?