The basic principle behind zener diode working is based on the cause of breakdown when the diode is in the reverse biased condition. The limiting maximum power for a zener diode is given by pzvzizmax and is a function of the design and construction. The zener diodes limit the fault voltage to the hazardous area. A diode is a simple electrical device that allows the flow of current only in one direction. A zener diode is heavily doped to reduce the reverse breakdown. While regular diodes get damaged when the voltage across them exceeds the reverse breakdown voltage, zener diodes work exclusively in this region. One is called zener breakdown, and the other, impact or avalanche ionisation. Power diodes characteristics a power diode and thyristor devices are most important in different power electronic converter topologies. The special type of diode that can conduct in reverse bias is referred to as a zener diode. Zener diode is a special kind of diode which permits the flow of current in the forward direction as well as in reverse direction when the voltage is above a certain voltage known as breakdown or zener voltage. Working of a zener diode when the reverse bias voltage vvz, then the electric field is strong enough to pull the valence electrons from the host atoms on the pside which are accelerated to nside.
Zener diodes are simple and useful devices for building voltage regulator circuits, but are times when you may have to improvise in the absence of the proper zener diode. When a pn junction diode is reverse biased, the depletion layer becomes wider. This article discusses about a brief information about the construction and working of an avalanche diode. Zener diode examples and circuit analysis book pdf by. Zener diode as a voltage regulator zener diode is a silicon semiconductor with a pn junction that is specifically designed to work in the reverse biased condition. There are two types of mechanism by which breakdown can occur at reverse pn junction that are avalanche and zener breakdown. By using an led and a zener diode we can create a circuit which gives turns on the led when a. Diodes and diode circuits tlt8016 basic analog circuits 20052006 11 3. Zener diode as a voltage regulator working principles byjus.
The fixed voltage property of zener diodes makes them extremely handy as quick voltage references. Zener diode working on zener or avalanche breakdown modes, applications clamping, voltage reference and voltage regulator. A zener diode is one of the specially designed diodes that predominately works in reverse biased conditions. This manual was prepared to acquaint the engineer, the equipment. Simultaneously, you will see continuous reverse saturation current as a result. Special techniques are applied in the fabrication of zener diodes to create the required properties. Zener diode ak voltage regulator diode hai joki voltage regulat karne ke. Zener diodes when we first talked about practical diodes, it was mentioned that a parameter associated with the diode in the reverse bias region was the breakdown voltage, v br, also known as the peakinverse voltage piv. The zener diode working principles and its various.
Amps will flow when reverse biased and if the reverse voltage is increased enough the junction breaks down and current will begin to flow avalanche and zener breakdown. When forward biased, it behaves like a normal signal diode, but when the reverse voltage is applied to it, the voltage remains constant for a wide range of currents. In normal diodes, the breakdown voltage is very high and the diode gets damaged totally if a voltage above the breakdown diode is applied, but in zener diodes, the breakdown voltage is not as high and does not lead to permanent damage of the zener diode if the voltage is applied as the reverse voltage applied to the zener diode increases towards the. When a diode is heavily doped, its depletion region will be narrow. Nside will have an important variable of electrons and intensely few holes whereas the p aspect will have a more concentration of holes and intensely few electrons. This diode can conduct in forward bias just like a normal diode. Zener diodes cannot be tested individually with a multimeter. But ordinary pn junction diode connected in reverse biased condition is not used as zener diode practically. The basic principle of zener diode is the zener breakdown. This was a bad thing before the whole avalanche breakdown, large current. Diode working principle and types of diode electrical. It is because multimeters usually do not have enough input voltage to put the zener into breakdown region. If this reverse biased voltage across the diode is increased continually, the depletion layer becomes more and more wider.
April 7, 20 introduction a zener diode is a pn junction that has been specially made to have a reverse voltage breakdown at a specific voltage. Zener diode working, characteristics and application as. Even at this low voltage, the electric field intensity is strong enough to exert a force on the valence electrons of the atom such that they are separated from the nuclei. Join researchgate to find the people and research you need to help your work. A basic semiconductor diode can operate in forward bias but it cannot conduct during reverse bias. It is the current flowing through the device at reverse biased condition due to the flow of minority charge carriers zener impedance. A zener diode typically suffers a breakdown at a marginally lower voltage than a conventional diode does. In breakdown the voltage across the zener diode is close to. A zener diode is a type of diode that allows current to flow in the conventional manner from its. With 2 v across a 400 ohm resistor, the current through that resistor and the diode, in series is 5 ma. If we use dbreakz in a future circuit, it will have the 5v breakdown.
An avalanche diode is a one kind of diode that is designed to experience an avalanche breakdown at a particular reverse bias voltage. In our previous articles, we explain in detail about diodes, pn junction diode, semiconductors etc. Hbd854 zener theory and design considerations handbook. Furthermore, it is changed for all future diodes that use the dbreakz model. The two effects are totally different, although they produce. It acts as a diode, which can serve in electronics as a rectifier, logic gate, voltage regulator zener diode, switching or tuner varactor diode.
Breakdown voltage for commonly available zener diodes can vary widely from 1. The diode is named after clarence melvin zener, the man who discovered this peculiar effect. In the circuit above, there is 10 v across the zener diode, and 2 v across the resistor. A specific arrangement of diodes can convert ac to pulsating dc, hence it is sometimes also called as a rectifier. Friends is video me ham zener diode ke working principle and construction ke bare me discuss karenge. However, the main differences between them is that the latter is a controlled device when it is turned on.
The relationship is obtained by applying kvl and it is vs vg r im. The zener diode working principles and its various applications. There are two effects that can be used in zener diodes. Introduction to diodes the pn junction the pn junction is a homojunction between a ptype and an ntype semiconductor. These diodes are heavily doped in order to have narrow depletion region.
In case this kind of reverse biased voltage throughout the diode is raised consistently, the depletion layer will become a lot more larger. When reverse voltage vr applied to the zener diode exceeds the break down voltage vb, the process called avalanche breakdown occurs in the depletion layer and starts flow through the device and limits the reverse voltage. Zener diodes this worksheet and all related files are licensed under. Zener diode made specially to operate in the reverse breakdown region. A normal diode and a zener diode both work in reverse bias without any damage provided a resistor is put in series to limit the current in a reverse breakdown region. At the present time, zener diodes use silicon as the basic material in the. The series resistor limits current to the hazardous area, and is considered an infallible component. The operation of these diodes is normal as pn junction diodes but at the time of transient voltage its operation cha nges. In the case of normal diodes the diode damages at the break down voltage. But zener diode is specially designed to operate in the reverse breakdown region.
In this article, we are going to explain zener diode and its applications in detail. When the voltage across the terminals is reversed and the potential reaches the zener voltage or knee, the junction will break down and current will flow in the reverse direction a desired characteristic. The basic function of zener diode is to maintain a specific voltage across its. Zener diode as a voltage regulator working principles. The zener diode is a special type of diode that is designed to work in reverse bias and in the socalled zener region of the diode characteristic curve. Working principle of zener diode a zener diode is similar to conventional pn junction diode except that it is properly doped to achieve sharp breakdown voltage. Diode characteristics an ideal diode would block all current when reverse biased. Voltage regulation using zener diodes bryan witherspoon november 8, 2008 abstract in digital or mixedsignal applications, there is a need to precisely regulate the voltage entering or exiting a circuit.
It is that reverse bias voltage at the which junction breakdown completely and large current flows through the device at a constant potential reverse saturation current. The zener diode exhibits an apparently similar effect in addition to zener breakdown. Avalanche diodes are optimized for avalanche effect so they exhibit small but significant voltage drop under breakdown conditions, unlike zener diodes that always maintain a voltage higher than breakdown. A simple zener diode voltage regulator in the voltage regulator the zener diode operates in the breakdown region, which ensures approximately constant voltage across it. This manual was prepared to acquaint the engineer, the equipment designer and manufacturer, and the experimenter with the fundamental principles, design characteristics. Because of this, a technique remarked as diffusion takes place. Its characteristics are otherwise very similar to common diodes. Avalanche diode construction, working and its applications. This type of breakdown occurs for a reverse bias voltage between 2 to 8v. Throughout this methodology, free electrons which are from n aspect will spread into the p aspect and recombine with. An ordinary diode operated in this region will usually be destroyed due to excessive current. The zener diode has a unique property that offers a simple, lowcost solution to this problem.
At the same time, there will be a constant reverse saturation current due to minority carriers after certain reverse voltage across the junction, the. There is nothing particular about zener diode working in reverse bias. They are more heavily doped than ordinary diodes, due to which they have narrow depletion region. The zener diode barrier works by diverting potentially dangerous energy to ground before it can reach the hazardous area. Tvs diodes, esd protection, transient voltage suppressors created date. Zener diode symbol zener diode circuit zener diode vi characteristics zener diode working zener diode applications faqs. Analysis of networks employing zener diodes is quite similar to that applied to the analysis off semiconductor i d t diodes di d iin previous i sections. Zener diode characteristics, working and applications. Zener diode is a silicon semiconductor with a pn junction that is specifically designed to work in the reverse biased condition. Whenever a pn junction diode is reverse biased, the depletion layer results in being wider. Identify which area of this curve represents normal forwardbiased operation, and which. Zener diode barrier principle instrumentation tools. Zener diodes vary in specifications such as nominal working voltage, power dissipation, maximum reverse current, and packaging.
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