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Presentation on the TopicZENER DIODE AS A

VOLTAGE REGULATORTO,RAVINDRA MEENA SIRHOD Ist YEAR

PRESENTED BY,SANJAY(K12336), SABIHA(k12783),ROHIT(k)IInd Sem , 1st Year, Section AA-3 Batch

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CONTENTSIntroduction to Zener Diode

Types of Zener Diodes

Applications of Zener diode

Zener Diode As a Voltage Regulator

Circuit Diagram

I-V Characterstics of Zener Diode

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ZENER DIODE

Zener diodes are a special kind of diode which permits current to flow in the forward direction.

It is different from others diodes Zener diodes will also allow current to flow in the reverse direction when the voltage is above a certain value.

This breakdown voltage is known as the Zener voltage.

Zener diodes are designed in a way where the Zener voltage is a much lower value.

There is a controlled breakdown which does not damage the diode when a reverse current above the Zener voltage passes through a Zener diode.

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Types Of Diodes There are many different kinds of Zener diodes :

The most common types categorized by power dissipation, nominal working voltage, forward (drive) current, forward voltage, packaging type and maximum reverse current.

The parametric filters on our website can help refine your search results depending on the required specifications.

The most common values for nominal working voltage are 5.1 V, 5.6 V, 6.2 V, 12 V and 15 V.

We also carry Zener diodes with nominal working voltage up to 1 kV.

Forward (drive) current can have a range from 200 uA to 200 A, with the most common forward (drive) current being 10 mA or 200 mA.

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Applications Of Zener DiodeZener diodes can be found in several applications. Some of these are:

voltage stabilizers or regulators (in shunt mode), surge suppressors for device protection, peak clippers, switching operations, reference elements and in meter protection applications.

The constant reverse voltage of a Zener diode renders it a very useful component in regulating the output voltage against variations in the load resistance or variations in the input voltage from an unregulated power supply.

The current through the Zener diode will change in order to keep the voltage within the threshold limits of Zener action and the maximum power that it can dissipate.

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Appratus Required:-ZENER DIODE

RESISTORS

INPUT VOLTAGE SOURCE

REHOSTATE (VARIABLE RESISTOR)

LOAD RESISTANCE

Zener Diode as a Voltage Regulator

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Zener Diode:-Suppose we have an unstable 12 Volt supply voltage and need a stable output of 8 Volts to power a 100mA device. 12 volts is sufficiently above 8 volts to ensure that any ripples in the supply will not take us below our target voltage. Than Since we need 8 Volts we can choose between a 7.5V or an 8.2V zener diode. 8.2V is close enough to our target voltage so we choose a zener diode with an 8.2 Volt zener voltage.

Selecting Power Rating Of Zener Diode:-

Zener diodes are available in a range of difference power ratings. If a large current flows through a small zener diode it will be destroyed, therefore we calculate the power to be lost in the diode and select a diode rated above that value. Here the zener power rating is equal to the zener voltage multiplied by the maximum current (Imax) calculated above which equals 8.2 * 0.110 = 0.9 Watts. Therefore a 1.3 Watt power rated zener diode should be perfect.

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Resistor:-The voltage dropped across the resistor is equal to the difference between the source voltage and the zener voltage = 12-8 = 4 Volts, and therefore the resistance according to Ohm's Law is the voltage drop divided by Imax = 4/0.110 = 36 Ohms so choose a 39 Ohm resisitor.If the source voltage is likely to be much over the 12 Volts stated then the voltage dropped across the resisitor will be larger and so a resistor with a larger resistance may be required.

Selecting Power Rating Of Resistor:-

The power dissipated in the resistor is equal to the voltage drop across the resistor multiplied by Imax. Therefore in this example power = 4 * 0.110 = 0.440 Watts. Using a 0.5 Watt resistor would be cutting it a bit fine - particularly if the source voltage is going to fluctuate higher regularly, therefore a 1 or 2 Watt rated resisitor should be used here despite it costing a few pennies extra.

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Zener Diode as a voltage regulator

Working:-When the input d.c voltage across zener diode increases beyond a certain limit (i.e. zener breakdown voltage), the current through the circuit rises sharply,causing a sufficient increases in the voltage drop across the dropping resistor R. As a result of it, the voltage across the zener diode remains constant and hence the output voltage lowers back to normal value.

When the input d.c. voltage across zener diode decreases, the current through the circuit goes down sharply causing sufficient decrease in the voltage across the dropping resistor . As a result of it, the voltage across the zener diode remains constant and hence the output voltage is raised to normal. Hence the output voltage remains constant.

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CIRCUIT DIAGRAM

R

R (load)+ +

- -FLUCTUATINGD.C. INPUT VOLTAGE

CONSTANTOUTPUT VOLTAGE

NP

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Simulation Of Main Circuit On Proteous Software

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I-V Characterstics of Zener diode

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Result:-Hence with the help above given facts and the simulation on proteous software correctly it is clear that above circuit for working of zener diode as a voltage regulator is fully correct and is working properly. So now when we noted the the reading of voltmeter which is being connected parallel to our load resistance we got the constant reading of voltage. So our zener diode is now truly works as a voltage regulator.

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Thank You