In this video, the basics of zener diode is explained and how the zener diode can be used as a voltage regulator in the various circuit is. Zener diode as voltage regulator and its vi characteristics. To analyze a circuit with a zener diode in it, you do the same thing you do with a circuit that has a normal diode. A zener diode exhibits a certain change in v z for a certain change in lz on a portion of the linear characteristic curve between izk and izm as illustrated in figure. Zener diode operation and applications ece tutorials. Such a circuit is also named an emitter follower voltage regulator. But when it is reverse biased above a certain voltage known as zener breakdown voltage or zener voltage or avalanche point or zener knee voltage the voltage remains constant for a wide range of current clarence zener is the scientist who discovered this electrical property.
This circuit lowers the output voltage by zener diode as a quantity that is equal to the zener voltage shifter diodes breakdown voltage. The only way to tell which device has failed is to remove the resistors and check them with an ohmmeter. A zener diode is also called a voltagereference, voltage regulator or breakdown diode. The main use of zener diode lies in the fact that the voltage across a zener diode remains constant for a larger change in current. Zener diodes as voltage regulators a circuit diagram symbol for a zener diode. Calculation of resistance to obtain a reference voltage of 3v from a supply voltage of v s 6v using a zener diode of 3v. The voltage at the top of the zener is going to be vz assuming it is reverse conducting, which it is in the first circuit. Zener diode, circuit, voltage regulator, digital, mixed signal introduction low voltage, low current applications like digital or mixedsignal circuitry require precise voltages for certain tasks like powering a microcontroller, or providing a reference voltage for measurements. As we know if the voltage across the diode exceeds a certain value it would draw excessive electric current from the supply. The stabilised output voltage is always selected to be the same as the breakdown voltage vz of the diode.
Voltage regulatora zener diode can be applied in a voltage regulator circuit to regulate the voltage applied to a load, such as in a linear regulator. Recall, from the discussion of the diode characteristics curve,that when a diode reaches reverse breakdown, its voltage remains almost constant even through the current changes drastically, and this is the key to zener diode operation. In our previous articles, we explain in detail about diodes, pn junction diode, semiconductors etc. In the circuit above, there is 10 v across the zener diode, and 2 v across the resistor. Vr voltage across the resistor, vs input voltage, vz zener voltage, iz breakdown current or current through zener. Zener diodes the simplest of all voltage regulators is the zener diode voltage regulator. Zener diode symbol and application as voltage regulator.
In the above circuit the zener diode of zener voltage v z is connected. In a zener diode voltage regulator circuit,the source series resistance rs 20 ohm. We use zener diodes for voltage regulation and voltage stabilisation. The d1 diode is a zener type diode and it is used for voltage reference. Zener limiting zener diodes can used in ac applications to limit voltage swings to desired levels. Ppt diodes powerpoint presentation free to download. It provides a constant voltage to the load from a source whose voltage may vary over a sufficient range. The figure below shows the circuit arrangement of zener diode as a regulator. Zener diode voltage regulators s bharadwaj reddy june 3, 2017 december 12, 2018 zener diodes can be used to produce a stabilised voltage output with low ripple under varying load current conditions. The zener diode can be used as a voltage regulator because in the breakdown region, the voltage of the zener diode becomes constant no matter how high the current goes. They are more heavily doped than ordinary diodes, due to which they have narrow depletion region. Zener diode can work as a voltage regulator if it is introduced in a circuit. The most widely known is as a voltage reference in some form of voltage regulator, but they can also be used as waveform limiters for circuits where it may be necessary to limit the excursion of a waveform to prevent overload, etc. Applications of zener diodes voltage regulator, meter.
Zener diodes can be used to produce a stabilised voltage output with low ripple under varying load current conditions. Zener diode characteristics in the forward region, the zener diode acts like a regular silicon diode, with a 0. Zener diodes are designed in a way where the zener voltage is a much lower value. A simple circuit involving zener diode as a regulator requires a resistor of low value connected in series with the input voltage source. The low value is required so as to allow the maximum flow of current through the diode, connected in parallel.
When reverse biased voltage applied to the zener diode reaches zener voltage, it starts allowing large amount of electric current. Zener diode voltage regulator ppt video online download. The zener diodes have a voltage rating equivalent to the intended output voltage, that may be closely match the desired output value. Electronics tutorial about the zener diode and how the zener diode can be used with a series resistor to produce a zener diode voltage regulator circuit. This breakdown voltage is known as the zener voltage. So if vs is also vz, then r2 has no voltage across it and, hence, no current through it.
The load voltage equals breakdown voltage vz of the diode. This property allows the use of the zener diode as a simple voltage regulator. Zener diode voltage regulator aliv bangladesh slideshare. The input voltage comes from a rectifier and has a ripple that ranges between 8.
Zener controlled transistor series voltage regulator. How a zener diode can be used as a voltage regulator answers. By passing a small current through the diode from a voltage. There are two kinds of zener controlled transistor voltage regulators. The zener breakdown voltage is the minimum reverse biased voltage below which the diode. Zener diode shunt regulator shunt regulators are normally only used for applications where the load power is not much often only milliwatts and rarely more than a few hundred milliwatts because under the worst case situation of no load the zener has to dissipate the full load power. This makes it possible to use a zener diode as a constant voltage device or a voltage.
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 is a controlled breakdown which does not damage the diode when a reverse current above the. Stabilitron zener diodes are designed to stabilize or reduce voltage. When correctly reserve biased, the zener diode keeps the voltage across its leads close to the zener breakdown voltage. If the resistors are good, then zener diode is bad. The major application of a zener diodes in the electronic circuit is as a voltage regulator. In a dc circuit, zener diode can be used as a voltage regulator or to provide voltage reference.
The zener voltage regulator consists of a current limiting resistor rs connected in series with the input voltage vs with the zener diode connected in parallel with the load rl in this reverse biased condition. At this point, a small increase in reverse voltage will rapidly increases the electric current. Zener diode as a voltage regulator linkedin slideshare. Design for an opamp voltage regulator circuit to drive a load of 6v,1. The basic purpose of a power supply is to provide one or more fixed voltages to the working circuit, with sufficient current handling capacity to maintain the operating conditions of the circuit. Career point cares zener diodes are a special kind of diode which permits current to flow in the forward direction. A zener controlled voltage regulator is used when the efficiency of a regulated power supply becomes very low due to high current. Zener diode voltage regulator a zener diode is also called a voltagereference, voltage regulator or breakdown diode. Voltage regulators,circuits,types,working principle. Because of this sudden rise in electric current, breakdown occurs called zener breakdown.
Ppt zener diode applications powerpoint presentation. A zener diode is one of the specially designed diodes that predominately works in reverse biased conditions. Used for operation in the reverse breakdown region. Zener diodes are used for voltage regulation, as reference elements, surge suppressors, and in switching applications and clipper circuits.
While regular diodes get damaged when the voltage across them exceeds the reverse breakdown voltage, zener diodes work exclusively in this region. Career point cares zener diodes can be found in several applications. The zener diode working principles and its various. Zener diode is a reverse biased heavily doped semiconductor silicon or germanium pn junction diode, which is operated exclusively in the breakdown region. Zener diode as voltage regulator tutorial electronicstutorials. When a supply must deliver a lot of current, a power transistor is used along with the zener diode as shown below. If source voltage vs can vary from 20 volt to 30 volt,find the maximum and minimum current in the diode. A zener voltage regulator is one which uses zener diode for regulating the output voltage. The fixed voltage property of zener diodes makes them extremely handy as quick voltage references.
Thats not a voltage regulator, its just a voltage divider until the voltage drop across rl starts getting close to 0. It is a special kind of diode which permits current to. Help understanding a zener diode as a voltage regulator. The zener diode mainly operates in reverse biased condition.
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. We have already discussed the details regarding zener diode in. Stabilitron zener diodes are designed to stabilize ppt. The output voltage of regulator system is fixed as the zener knee voltage of the zener diode and can be used in power devices requiring a fixed voltage of firm value. In this article, we are going to explain zener diode and its applications in.
Zener diode is a general purpose diode which behaves like a normal diode when forward biased knee voltage breakdown avalanche used as. A zener diode is one of the specially designed diodes that predominately works in reverse biased. Zener breakdown occurs at a voltage much less than the avalanche breakdown voltage. Voltage regulator circuits using transistor and zener diode. Zener diode as a voltage regulator working principles. A zener diode is a special diode that is optimized for operation in the breakdown region. Z ener diode as the name suggests is a two terminal device with two terminals being anode p and cathode n. They provide a lowcost and no frill method for voltage regulation. This application of the zener diodes relies heavily on the ability of the zener diodes to maintain a constant voltage. They are designed to breakdown in a reliable and nondestructive way so that. The breakdown region voltage of a zener diode is set by carefully controlling the doping level during manufacture. Zener diode as voltage regulator diode pn junction scribd. Ppt zener diode voltage regulator powerpoint presentation, free. This is arguably the most common application of zener diodes.
The zener diode will continue in regulating the voltage till the zener diode current falls below the minimum i z min value in the reverse breakdown region. 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. The basic diagram of zener diode as voltage regulator is given. Zener diode is a general purpose diode, which behaves like a normal diode when forward biased. 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. 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. The critical parameter of this type of diodes is the zener breakdown voltage. Zener diode working, characteristics and application as. A 4v7 zener diode is used as a voltage regulator as shown in the diagram below. Opamp voltage regulator concept circuitlib electronics. The symbol of zener diode is shown in the figure below. Typically there is also a minimum current required for the operation of the diode. Zener diodes are used in circuits to maintain a fixed voltage across a load.
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