Working of the zener diode is similar to a pn junction diode in forward biased condition, but the uniqueness lies in the fact that it can also conduct when it is connected in reverse bias above its threshold breakdown voltage. The zener diode is used in its reverse bias or reverse breakdown mode, i. Diode circuits operating in the reverse breakdown region. Introduction to zener diodes evil mad scientist laboratories. How to solve diode circuit problems in series and parallel. And while that sounds a bit esoteric, theyre actually among the handiest components ever to cross an engineers bench. Zener voltage z 1 10 100 1,000 1 10 100 v, zener voltage v fig. Introduction to zener diode the engineering knowledge. Introduction the zener diode is a silicon pn junction devices that differs from rectifier diodes because it is designed for operation in the reversebreakdown region.
The schematic symbol for a zener diode is shown above it is very similar to that of a regular diode, but with bent edges on the bar. A diode is an electrical device allowing current to move through it in one direction with far greater ease than in the other. A zener diode is constructed for operation in the reverse breakdown region. Write down all circuit equations and simplify as much as possible 2. Zener effect dominates at reverse voltages less than 5 volt whereas avalanche effect dominates above 5 v. Diodes are also built into many digital integrated circuits to protect them from dangerously large voltage spikes. 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. Pdf explain a little about the zener diode sina taherinasab. V z0 is the voltage at which the straightline approximation of the iv characteristic intersects the horizontal axis.
In the forward bias region, the zener behaves like a regular diode within specified. Zener diodes are designed to operate in the reverse breakdown region. A zener diode is a type of diode that allows current to flow in the conventional manner from its anode to its cathode i. Difference between avalanche breakdown and zener breakdown.
One of the most widely used semiconductor components is the diode. The reverse breakdown of a pn junction may occur either due to zener effect or avalanche effect. Zener diodes are normal pn junction diodes operating in a reverse biased condition. Page three or four of every beginners guide to electronics c.
If a diode is fully conducting, it can usually be assumed that the voltage across it is the forward voltage rating. The zener diode is a special type of diode that allows current to flow through it in either direction, however only at certain voltages. 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. It is an electronic device which allows the flow of current in one direction only. In general diode current flows in only forward biasing condition and block the flow of current in reverse biasing conditions. If youre not familiar with zener diodes, then an introduction is appropriate. Because of its unusual properties it fills a longstanding need in electronic circuitry. An ordinary diode operated in this region will usually be destroyed due to excessive current. When the reverse voltage is sufficiently increased, the junction breaks down and a large reverse current flows. Introduction the nonlinear diode model the circuit schematic symbol of a diode is shown in figure 5.
Basic electronics notes on vi characteristics of zener. A zener diode is a type of diode that permits current to flow in the forward. A multimeter with a diode setting can be used to measure the minimum of a diodes forward voltage drop. Zener diode in may applications, operation in the reverse breakdown region is highly desirable. The zener diode working principles and its various. Zener diodes are made specially to operate in this region. Its characteristics are otherwise very similar to common diodes. Basic diode electronics introduction to diodes the pn junction the pn junction is a homojunction between a ptype and an ntype semiconductor. The zener still conducts electricity in the forward direction like any other diode, but also conducts in the reverse direction, if.
When a junction diode is reverse biased, normally only a very small reverse saturation current flows. Excessive temperature will destroy a zener diode, and because it both drops voltage and conducts current, it produces its own heat in accordance with joules law pie. The nonlinear, and polarity characteristics of the diode make for a very interesting and useful device albeit at the expense. It provides, among other useful functions, a constant voltage reference. In breakdown the voltage across the zener diode is close to. Basics currentvoltage characteristic of a zener diode with a breakdown voltage of 17 volt.
Introduction before entering the topic we should briefly know about the diodes, what is diode. Zener diodes diodes that can be made to conduct backwards. Outlines introduction of zener diode construction of zener diode working of zener diode application of zener diode numerical of zener diode 3. 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. Introduction and application of zener diodes in a typical. Recipe for solving diode circuits state of diode is unknown before solving the circuit 1. This was a bad thing before the whole avalanche breakdown, large current. A zener diode is a type of diode that allows current to flow in the conventional manner from its. Introduction to diodes and rectifiers chapter 3 diodes and rectifiers pdf version. A zener diode is a silicon semiconductor device that permits current to flow in either a forward or reverse direction. The zener diode is a specialized silicon diode that looks like a normal silicon diode in the forward direction. The zener diode has a unique property that offers a simple, lowcost solution to this problem. Zener diode as voltage regulator tutorial electronicstutorials. This application note discusses the implementation of this voltage regulator and its advantages and drawbacks.
A zener diode is a particular type of diode that allows current to flow not only from its anode to its cathode, but also in the reverse direction, when the socalled zener voltage is reached. Introduction regulator zener diode regulator for low current power supplies a simple voltage regulator can be made with a resistor and a zener diode connected in reverse. 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. A semiconductor diode blocks current in the reverse direction, but will suffer from premature breakdown or damage if the reverse voltage. It is basically made of semiconductors which have two.
Zener diodes are a special type of semiconductor diode devices that allow current to flow in one direction only that also allow current to flow. In this lesson we will learn how zener diodes affect ac and dc signals and perform some experiments to see those effects. Zener diodes are rated by their breakdown voltage v z and maximum power p z typically 400mw or 1. 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. Objective in this lab you are to measure iv characteristics of rectifier and zener diodes in both forward and reversebias mode, as well as learn to recognize what mechanisms cause current flow. Diodes and diode circuits tlt8016 basic analog circuits 20052006 11 3. Use the diode equation for that state to solve the circuit equations and find i d and v d 3. Like any semiconductor device, the zener diode is sensitive to temperature. A point contact diode with glass encapsulation and a schottky diode. A diode is simply a pn junction see introduction into semiconductor physics with the following characteristics.
In todays tutorial, we will have a look at introduction to zener diode. Once you graduate from the simple, passive components that are resistors, capacitors, and inductors, its time to step on up to the wonderful world of semiconductors. Clarence melvin zener the american physicist invented zener diode. The active portion of a zener diode is a semiconductor pn junction. This effect, called zener breakdown, occurs at a precisely defined voltage, allowing the diode to be used as. It acts as a diode, which can serve in electronics as a rectifier, logic gate, voltage regulator zener diode. Zener diodes are a special type of semiconductor diode devices that allow current to flow in one direction only that also allow current to flow in the opposite direction, but only when exposed to enough voltage. Zener diodes characteristics circuit symbol equivalent.
The diode is two terminal non linear device whose iv characteristic besides exhibiting nonlinear behavior is also polarity dependent. Zener diodes an introduction to analog electronics pyroedu. Zeners are so useful they should be found in every experimenters component collection. The reverse breakdown voltage is relatively insensitive to the current flowing thought the diode the reverse current. It exhibits high resistance in one direction and low resistance in other direction. A zener diode is heavily doped to reduce the reverse breakdown voltage. This electronics video tutorial provides a basic introduction into zener diodes which is used as voltage regulators in dc circuits. A simple zenerdiode voltage regulator in the voltage regulator the zenerdiode operates in the breakdown region, which ensures approximately constant voltage across it. Under forward bias, it needs a small voltage to conduct. Zener diode, circuit, voltage regulator, digital, mixed signal introduction low voltage.
Currentvoltage characteristic of a zener diode with a breakdown voltage of 17 volt. Afroman is back again with another great tutorial video on the basics of electronics. Zener diodes with glass or black resin encapsulation. The filtering discussion in section b7 introduced the reduction of output. The principle behind the diode is similar to a valve or a gate, which lets electricity flow only in one direction simple. The diode consists of a special, heavily doped pn junction, designed to conduct in the reverse direction when a certain specified voltage is reached. Hbd854 zener theory and design considerations handbook. 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.