Zener diode examples and circuit analysis book pdf by alvin. Zener controlled transistor series voltage regulator such a circuit is also named an emitter follower voltage regulator. We call this particular regulator circuit the shunt regulator. L is equal to the zener breakdown voltage v zkregardless of the value of load resistor r l or source voltage v s provided, of course, that the zener diode is in 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. Apr 27, 2019 in this tutorial, we will learn about different types of diodes. Special diodes zener diodes diodes and diode circuits. This is an example of a primary application of zener diodes voltage regulation. Applications of zener diodes voltage regulator, meter. The zener diode has a unique property that offers a simple, lowcost solution to.
Zener diodes as voltage regulators a circuit diagram symbol for a zener diode. In this article, we are going to explain zener diode and its applications in. Diodes and diode circuits tlt8016 basic analog circuits 20052006 11 3. Such junctions show a pronounced rectifying behavior. In this article, we are going to explain zener diode and its applications in detail. When connected in parallel with a variable voltage source so that it is reverse biased, a zener diode conducts when the voltage reaches the diode s reverse breakdown voltage. The symbol for the zener diode or break down diode is shown on the circuit. An ideal diode will have zero resistance in one direction, and infinite resistance in the reverse direction. In the last lecture, we had commented that a normal diode which is not allowed to go into the breakdown region, a normal diode. The zener diode working principles and its various applications.
For zener diode voltage remains constant in break down region and current carrying capacity in high. The actual diode power dissipation is calculated multiplying the forward voltage drop. Zener diodes are designed to operate in the reverse breakdown region. 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. This was a bad thing before the whole avalanche breakdown, large current. All the diodes that weve been looking at up till this point, if we operate them in reverse voltage they either look like an open circuit or, if you put too much. It is called so because the transistor used is connected in an emitter follower configuration. Zener diode in may applications, operation in the reverse breakdown region is highly desirable. Types of diodes and their applications 24 types of diodes. Zener diodes design support tools available features silicon planar power zener diodes for use in stabilizing and clipping circuits with high power rating the zener voltages are graded according to the international e 24 standard. The actual diode power dissipation is calculated multiplying the forward voltage drop and the forward current. It acts as a diode, which can serve in electronics as a rectifier, logic gate, voltage regulator zener diode. Explain how normal diodes might be used as crude substitutes for a zener diode in the following circuit. Gate 2011 electronics and communication engineering set nptel.
In the last class, we saw that the diode can be used in the breakdown region as a zener diode and it can be primarily giving you secondary power sources called. The vi characteristic of zener diode indicates that characteristic of zener diode in forward bias is same as pn junction diode. Example zener diode circuit analysis blank ku ittc. Zener diodes are used in circuits to maintain a fixed voltage across a load. Diode circuits operating in the reverse breakdown region. Zener diode temperature characteristic it can be seen in the example given that there is a noticeable difference between the specification for the zener diode reverse voltage at 0c and 50c. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. In our previous articles, we explain in detail about diodes, pn junction diode, semiconductors etc. They are also called pn diodes in analogy with vacuum diodes. The pn junction is a versatile element, which can be used as a. Introduction to basic electronics, electronic devices, semi conductor diodes, wave shaping using diodes, zener diode characteristics, transistor biasing. A diode is defined as a twoterminal electronic component that only conducts current in one direction so long as it is operated within a specified voltage level.
User may specify either, both, or neither of the at least and no more than values. Diodes zener diodes photodiodes optical isolation basic diode operation application. Zener diode breakdown voltages can range from 2 to 200 v. For a pn junction, match the type of breakdown with phenomenon i. V z zener voltage v z is the reverse voltage at which breakdown occurs in a zener diode. Use the diode equation for that state to solve the circuit equations and find i d and v d 3. Zener diodes are created to operate optimally when they are reversebiased and, instead of being destroyed, will conduct electricity under conditions where normal a diodes breakdown voltages are reached. Use the diode equation for that state to solve the circuit equations and find i. For a 10v zener diode, the output voltage range is much less than the input range. A heavily doped semiconductor diode which is designed to operate in reverse direction is known as the zener diode.
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. Zener diode working, characteristics and application as. Zener diodes can be used to produce a stabilised voltage output with low ripple under varying load current conditions. In this tutorial, we will learn about different types of diodes. Chitralekha mahanta, department of electronics and communication engineering,iit guwahati. Aug 31, 2008 lecture series on electronics for analog signal processing i by prof.
A zener diode is a diode that breaks down at a specific voltage when it is reverse biased. Zener diode is nothing but a single diode connected in a reverse bias mode and zener diode can be connected in reverse bias positive in a circuit as shown as picture. Find the voltage at the output terminals assuming ideal diodes. A simple zenerdiode voltage regulator in the voltage regulator the zenerdiode operates in the breakdown region, which ensures approximately constant voltage across it. Lets try again, this time with our friend, the zener diode. Feb 09, 2015 construction of zener zener diodes are designed to operate in reverse breakdown. Mahanta, department of electronics and communication engineering,iit guwahati. This needs to be taken into account if the circuit and equipment in which the zener diode is to be used is subject to temperature change. Write down all circuit equations and simplify as much as possible 2. Zener diode examples and circuit analysis book pdf by. P517617 lec 5, p7 transistors transistors are the heart of modern electronics replaced vacuum tubes voltage and current amplifier circuits high frequency switching computers impedance matching low power small size, can pack thousands of transistors in mm2 in this class we will only consider bipolar transistors. The reverse breakdown voltage is relatively insensitive to the current flowing thought the diode the reverse current.
One is called zener breakdown, and the other, impact or avalanche ionisation. Pn diodes forward bias, small signal model, bjts prof j. The first one is the normal diode the second one is a circuit symbol for a zener diode or the voltage regulator diode and the next one is a the varactor diode which. 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. P517617 lec5, p1 diodes and transistors diodes what do we use diodes for. In other words, the diode which is specially designed for optimising the breakdown region is known as the zener diode. Construction of zener zener diodes are designed to operate in reverse breakdown.
Pn junctions consist of two semiconductor regions of opposite type. Zener diodes are created to operate optimally when they are reversebiased and, instead of being destroyed, will conduct electricity under conditions where normal a diode s breakdown voltages are reached. Clamping basic diode operation reverse bias terry sturtevant electronics zener diodes and photodiodes. Easily share your publications and get them in front of issuus. 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. Radhakrishna rao, department of electrical engineering,iit madras. Zener diodes are widely used as voltage references and as shunt regulators to regulate the voltage across small circuits. Now these are the characteristics i v characteristics of a what we call zener diode. Electrical characteristics tamb 25 c, unless otherwise specified part number zener voltage range 1 test current reverse leakage dynamic resistance f 1 khz surge current 3 regulator 2. Lecture series on electronics for analog signal processing i by prof. Zener voltage z 1 10 100 1,000 1 10 100 v, zener voltage v fig.
The zener diode working principles and its various. By passing a small current through the diode from a voltage source, via a suitable current limiting resistor r s, the zener diode will conduct sufficient current to maintain a voltage drop of vout. Terry sturtevant electronics zener diodes and photodiodes. Finally, lets try using one fat 20 v zener diode type 1n5357brlg, to drop some of the load. Applications of zener diodes zener diodes finds a wide applications commercially and industrially. Basic electronics and lab online course video lectures by iit madras. A zener diode, when used in voltage stabilization circuits, is biased in a reverse bias region below the breakdown voltage b reverse breakdown region c forward bias region d forward bias constant current mode. It could be with a voltage source corresponding to vz which is the beak down voltage and a series resistance rz. Basic idea about forward bias, reverse bias and vi characteristics, ideal diode, second and third approximation, surface mount diodes, zener diode, testing of diode with multimeter.
There are two effects that can be used in zener diodes. In reverse bias, a negligible constant current flow through the zener diode but the current becomes abruptly large at certain voltage. 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. Sep 01, 2008 lecture series on electronics for analog signal processing i by prof. Lecture 10 zener regulator and voltage regulator youtube. The two effects are totally different, although they produce. When the zener diode is operated in the breakdown or zener region, the voltage across it is substantially constant for a large change of current through it. Basic diode electronics introduction to diodes the pn junction the pn junction is a homojunction between a ptype and an ntype semiconductor.
Jan 04, 2020 a diode is defined as a twoterminal electronic component that only conducts current in one direction so long as it is operated within a specified voltage level. A zener diode is a type of diode that allows current to flow in the conventional manner from its anode to its cathode i. Zener diode forward bias when a zener diode is forward biased, it operates as a normal diode. Some of the important applications of a zener diodes are as a voltage regulator or stabilizer, as a meter protector and as a wave shaper. Zener diode working with circuit diagram and applications. This will be a brief note on different types of diodes with basic functionality and its circuit symbol. Restriction of hazardous substances rohs is a european union eu directive that requires all manufacturers of electronic and electrical equipment sold in europe to demonstrate that their products contain only minimal levels of the following hazardous substances.
Gate questions on zener diode 1987 to till date 1988. Oct 12, 2016 issuu is a digital publishing platform that makes it simple to publish magazines, catalogs, newspapers, books, and more online. A zener voltage regulator is one which uses zener diode for regulating the output voltage. Smith department of eecs university of california, berkeley. Replace suffix c with b for 2 % tolerance aecq101 qualified. For the zener diode shown in the figure, the zener voltage at knee is 7 volts, the knee current is negligible and the zener dynamic resistance is 10 if the input voltage v i range is 10 to 16 volts, the output voltage v o ranges from. Zener breakdown occurs in a zener diode at low reverse voltages. Definition, symbol, and types of diodes electrical4u. A tunnel diode is a heavily doped pn junction diode in which the electric current decreases as the voltage increases in tunnel diode, electric current is caused by tunneling. In the circuit shown below, the norton equivalent current in amperes with respect to the terminals. Clamper circuit the input voltage is a sine wave with 10v peak for the following circuit.
A zener diode is much like a standard diode in many respects, except that it is designed to operate in and notice here the reverse breakdown region of its operating curve. Tunnel diode definition, symbol, and working diode. Essentially, it allows an electric current to flow in one. Zener diodes are normal pn junction diodes operating in a reverse biased condition. 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 can be designed to have a breakdown voltage over a wide range from 0. Zener diode this voltage regulator is a pn junction diode that has a precisely tailored impurity distribution to provide a welldefined breakdown voltage. We have already discussed the details regarding zener diode in basic electronics tutorial. The minimum value of r so that the voltage across it does not fall below 6 volts. Types of diodes small signal, led, schottky, zener.
These include small signal diodes, zener diodes, light emitting diodes, schottky diodes, tunnel diodes, avalanche diodes, etc. Products returned as matches will meet all specified criteria. 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 circuit consists of an npn transistor and a zener diode. This effect, called zener breakdown, occurs at a precisely defined voltage, allowing the diode to be used as a precision voltage. Two types of reverse breakdown in a zener diode are avalanche and zener. Then, the output on the anode of the zener is just 16 v, well within the safe input range of the regulator.
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