Voltage regulators,circuits,types,working principle. Diode operation no current flows because the holes and electrons are moving in the wrong direction. Zener diodes the simplest of all voltage regulators is the zener diode voltage regulator. Here the question arises where this type of diodes can be useful. Zener diode definition of zener diode by the free dictionary. It is fabricated by using heavily doped pside and nsides of the diode. It provides, among other useful functions, a constant voltage reference. Electronics tutorial about the zener diode and how the zener diode can be used. In such a situation, the diode is said to be off or reverse. This article covers the zener diode definition, working principle, characteristics, and applications. When a pn junction diode is reverse biased, the depletion layer becomes wider. Zener diodes are normal pn junction diodes operating in a reversebiased condition. Recipe for solving diode circuits state of diode is unknown before solving the circuit 1. Here we are going to explain about diodes and its types.
The depletion region shrinks allowing current to flow. A zener diode is a type of diode that allows current to flow in the conventional manner from its. The basic characteristic of all crystal diodes is the unidirectional conduction. Light emitting diode led working, construction and symbol. Basics currentvoltage characteristic of a zener diode with a breakdown voltage of 17 volt. Feb 23, 2019 in this physics video in hindi for class 12 we explained, with diagram, how zener diode is used as voltage regulator. 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. 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. Zener diode examples and circuit analysis book pdf by alvin. The depletion region of the zener diode is very thin because of the impurities. Tunnel diode definition, symbol, and working diode. Because of its unusual properties it fills a longstanding need in electronic circuitry. A diode is a simple electrical device that allows the flow of current only in one direction. Basic zener regulator analysis procedure step 1 determine the state of the zener diode by removing it from the network and calculating the voltage across the resulting open circuit.
Apart from the basic working of the diode, this video also explains vi characteristics and applications of diode rectification using bridge rectifier with help of animation. Diode is an electronic device conduct current in one direction i. The basic principle behind the working of a zener diode lies in the cause of breakdown for a diode. In reverse breakdown region high current flow through the diode leading to high power dissipation. Maximum current at the rated zener voltage vz200 ua to 200 a. Definition, symbol, and types of diodes electrical4u. At the same time, there will be a constant reverse saturation current due to minority carriers after certain reverse voltage across the junction, the. With the switch up, the zener will limit vout to 4 volts. Zener diode as voltage regulator semiconductor 11 in. It is constructed of a p and an n junction connected together. Zener diode definition working principle characteristics. Normally there are two types of breakdown zener and avalanche. If the voltage across a diode is negative, no current can flow, and the ideal diode looks like an open circuit. A silicon semiconductor device used as a voltage regulator because of its ability to maintain an almost constant voltage with a wide.
In other words, we can say that the concentration of free electrons is high and that of holes is very low in an ntype semiconductor. Diode working principle and types of diode electrical. As we have gone through the first part of the article we know what is zener diode and what is the basic principle of operation. Free electrons with sufficient kinetic energy collide with stationary ions of the depletion layer and knock out more free electrons. In our previous articles, we explain in detail about diodes, pn junction diode, semiconductors etc. In this physics video in hindi for class 12 we explained, with diagram, how zener diode is used as voltage regulator. A diode s working principle depends on the interaction of ntype and ptype semico nductors. 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. Most of the times a resistance has to be connected in series with it to limit the electric current flowing through the diode. Oct 09, 2018 a pn junction diode is a two terminal single crystal semiconductor device whose one side is doped with acceptors and other side by donors. The zener diode operates just like the normal diode when in the forwardbias mode, and has a turnon voltage of between 0. Doping with acceptor creates p type semiconductor while doping with donors produces n type. And the operating current and maximum allowable current for various types of diodes can be found in the manual.
The following image shows the symbol of a schottky diode. Zener diode not working as expected electrical engineering. A specific arrangement of diodes can convert ac to pulsating dc, hence it is sometimes also called as a rectifier. Zener diode working with circuit diagram and applications. Hence the zener diodes are provided with adequate power dissipation. In our previous articles, we explain basic theory of semiconductors, pn junction diode, and pn junction diode characteristics etc.
The zener diode working principles and its various applications. Basics currentvoltage characteristic of a zener diode with a breakdown voltage of. It works on the principle of zener breakdown and is operated in reverse breakdown region. Read more pn junction diode and its working principle. A pn junction diode is a two terminal single crystal semiconductor device whose one side is doped with acceptors and other side by donors. A light emitting diode led is an optical semiconductor device that emits light when voltage is applied. Zener diode working, characteristics and application as. The limiting maximum power for a zener diode is given by p zv zi zmax and is a function of the design and construction of the diode. Pin configuration, anode and cathode electronic symbol zener diode symbol2. Zener diode article about zener diode by the free dictionary. In tunnel diode, electric current is caused by tunneling. But zener diode is specially designed to operate in the reverse breakdown region. Types, operation and symbols guide analyse a meter.
Click here to visit the playlist on this chapter s. 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. Zener diode characteristics, working and applications. But zener breakdown voltage occurs when the reverse bias voltage is greater than a predetermined voltage. It is also used in highfrequency oscillators and amplifiers. When light emitting diode led is forward biased, free electrons in the conduction band recombines with the holes in the.
Working of the zener diode is similar to a pn junction diode in forwarding. Zener diode theory introduction the zener diode is a semiconductor device unique in its mode of operation and completely unreplaceable by any other electronic device. The main principle behind the working of such a regulator is that a large proportion of the change in supply or input voltage appears across the transistor and thus. Zener diode symbol zener diode circuit zener diode vi characteristics zener diode working zener diode applications faqs. The doping level of the zener diode is somewhat higher than the normal pn junction diode so that it can provide a sharp breakdown voltage. That means a large majority current flows through the device when the forward potential is applied to it. Zener diode examples and circuit analysis book pdf by. The tunnel diode is used as a very fast switching device in computers.
Diode working with animations electronicselectrical ee. An ntype semiconductor has plenty of free electrons and a very few numbers of holes. 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. However, when connected in the reverse mode, which is usual in most of its applications, a. Basic diode electronics introduction to diodes the pn junction the pn junction is a homojunction between a ptype and an ntype semiconductor. It is a metal semiconductor junction that does not have the capacity to store charges at their junction. The basic principle behind the working of a zener diode lies in the cause of breakdown for a diode in reverse biased condition. This manual was prepared to acquaint the engineer, the equipment. If this reverse biased voltage across the diode is increased continually, the depletion layer becomes more and more wider.
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. Hbd854 zener theory and design considerations handbook. A zener diode is a special diode that is optimized for operation in the breakdown region. Current trying to flow the reverse direction is blocked. Minimum current required for the diode to break down5 ma and 10 ma. In this article, we are going to explain zener diode and its applications in detail. In this video, we will explore the inner workings and applications of the diode in great detail. A zener diode is one in which the reverse breakdown occurs due to electron quantum tunneling under high electric field strength called zener effect. A special type of pn junction diode that operates in reverse biased condition, more specifically in breakdown region is known as zener diode. There are two types of mechanism by which breakdown can occur at reverse pn junction that are avalanche and zener breakdown. The zener diode is made up of heavily doped semiconductor material. Power is calculated by multiplying current by voltage pie, so we can calculate power dissipations for both the resistor and the zener diode quite easily.
A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. However, when connected in the reverse mode, which is usual in most of its applications, a small leakage current may flow. Zener diode is a junction formed by combining highly doped pn semiconductors. A diode can be defined as the fundamental electronic component that allows the flow of electricity in one direction only. As stated above the basic principle behind the working of a zener diode lies in the cause of breakdown for a diode in reverse biased condition. This is where the zener diode working comes into play. One day accidentally when the silicon crystal which has a crack in it was exposed to the sunlight, he found the flow of current through the crystal and that was later called as diode, which was the beginning of the semiconductor era. This causes the holes to move toward the depletion region and the free electrons to move toward the depletion region. Zener diode as voltage regulator tutorial electronicstutorials. Schottky diode working, characteristics, applications. These diodes are heavily doped in order to have narrow depletion region. Zener diode working, characteristics and application as voltage regulator by ajay kumar 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.
The most important physical parameter of this schottky diode is their fast switching rate and less forward voltage drop. 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. 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. A zener diode is a type of diode that allows current to flow in the conventional manner from its anode to its cathode i.
The operation of a zener diode is alike normal diode in forward biased mode. To understand how a zener diode works, just look at the reverse characteristics of it. Oct 12, 2016 basic zener regulator analysis procedure step 1 determine the state of the zener diode by removing it from the network and calculating the voltage across the resulting open circuit. Correspondingly, is there a way we could determine the type of breakdown action from experimental measurements on a zener diode. 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. The reference voltage is provided by the zener diode and the transistor acts as a variable resistor, whose resistance varies with the operating conditions of base current, ibase. 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. This was a bad thing before the whole avalanche breakdown, large current. Zener diode is a silicon semiconductor with a pn junction that is specifically designed to work in the reverse biased condition. Zener diode as a voltage regulator working principles. Diode theory diode as a conductor when a voltage is applied current will flow. The diode the diode is a two terminal semiconductor device that allows current to flow in only one direction. A zener diode is a silicon semiconductor device that permits current to flow in either a forward or reverse direction.
Zener diode characteristics in the forward region, the zener diode acts like a regular silicon diode, with a 0. It acts as a diode, which can serve in electronics as a rectifier, logic gate, voltage regulator zener diode. Zener diode definition a zener diode is a type of diode that permits current to flow in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger than the breakdown voltage known as zener knee voltage or zener voltage. Light emitting diode led working, construction and. The heavily doped means the highlevel impurities is added to the material for making it more conductive. Write down all circuit equations and simplify as much as possible 2. 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. At the present time, zener diodes use silicon as the basic material in the.
Zener diode is a special purpose pn junction diode. This reduces the width of depletion region thickness. A tunnel diode is a heavily doped pn junction diode in which the electric current decreases as the voltage increases. The zener diode working principles and its various. Zener diode is popularly used as shunt regulator or voltage regulator. Use the diode equation for that state to solve the circuit equations and find i d and v d 3. 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.
In the year 1940 at bell labs, russell ohl was working with a silicon crystal to find out its properties. Due to the gain in kinetic energy of the minority carriers, these free electrons in movement collide with the stationary ions. A diodes working principle depends on the interaction of ntype and ptype semico nductors. With the switch down, the zener will not conduct, and vout will be 3 volts less a bit, due to the current drawn by r2 without r1, when the switch is up, infinite current would flow through the zener diode as v1 tries to deliver 5 volts, and d1 tries to hold the voltage to 4 volts. Because of this, a technique remarked as diffusion takes place. Todays most commonly used diode is semiconductor diode. In the same way if the nside is connected to the positive terminal of the supply and the pside to the negative terminal of the supply, the diode is said to be reversed biased. In other words, led is an optical semiconductor device that converts electrical energy into light energy. Zener diode operation and applications ece tutorials. A zener diode is heavily doped to reduce the reverse breakdown voltage. An ordinary diode operated in this region will usually be destroyed due to excessive current.