10 March 2019

What is zener diode

Before we learn about Zener diode first let we understand what is a diode?

The semiconductor diode is a combination of two crystalline semiconductor materials, which designed the two materials know as p-type and n-type. So first let we understand what is n-type and what is p-type of materials

The n-type semiconductor has a larger electron concentration. This is done by introducing a donor as impurities. Here the n-type refers to the negative charge of the electron.

While in p-type of the semiconductor has larger hole concertation, here p-type refers as to the positive charge of the hole.

There are several types of diodes are available for use in electronics design namely a Gunn diode, Laser diode, LED, backward diode, BARITT diode, a PIN diode, PN junction diode, Tunnel diode, Schottky diode, Varactor diode, and Zener diode. Here this article gives the information about what is a diode, what is a Zener diode, different types of Zener diode, application, advantages etc.

What is a Zener diode?

The name of Zener diode was named after American physicist Melvin Zener who discovered the Zener effect. The Zener diode is widely used in all kind of electronic circuit equipment.

The Zener diode is a unique diode which allows the current to flow in one direction like a regular diode but is also permits it to flow in the opposite direction. It allows the flow in the opposite direction when the voltage is above a certain value as Zener voltage. Zener diode consists of a highly doped reversed biased, p-n junction diode while operating in the breakdown region.

In a normal diode, the breakdown voltage is very high and also the diode gets damaged totally if a voltage is above the breakdown diode is applied, but in Zener diodes, the breakdown voltage is not like too much high and does not lead to permanent damage of the Zener diode if the voltage is applied.

A Zener diode is a basically P-N junction type of semiconductor diode, which device designed to operate in the reverse breakdown region.  The Zener diode is always connected in reverse direction because it is specially designed to work in reverse direction. The breakdown voltage of the Zener diode is carefully set by controlling the doping level during manufacture.

The symbolic representation of the Zener diode is given below:
Zenor diode
Zener Diode

Zener diode characteristics of Zener diode:

The VI characteristics of Zener diodes shown in the figure given below. This curve shows that when Zener diode if forward bias, it works like a normal diode but when the reverse biased voltage applies across to the Zener diode, the Zener diode breakdown occurs in a different manner.

At Zener breakdown voltage the current stary flowing in the reverse direction, it allows only a small amount of leakage current until the voltage is less than Zener diode

At the certain value of reverse voltage, the reverse current will increase suddenly and sharply. This is an indication that the breakdown has occurred. Breakdown occurs called a Zener breakdown. However, the Zener diode exhibits a controlled breakdown that does damage the device.
Zener diode characteristics
Zener diode characteristics
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Different types of Zener diodes:
  • Normal diode 
  • Power dissipation
  • Forward voltage
  • Packing voltage
  • Forward drive current
  • Maximum reverse current
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Advantages of Zener diode:
  • High accuracy
  • Small size
  • Power dissipation capacity is very high
  • Low cost
Application of Zener diode:
  • Voltage regulation
  • Voltage reference
  • Switching operation
  • Clamping circuit
  • Various protection circuit
  • Waveform clipper
  • Voltage shifter
  • Voltage stabilizer
  • For meter protection
  • For wave shaping
  • As voltage stabilizer
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  • We all know that learn about the above topic we understand that this ordinary diode only that it has been doped to have a sharp breakdown voltage.
  • the diode maintains a stable output voltage irrespective of the input voltage provided the maximum Zener current is not exceeded.
  • The Zener diode default operational state is in the breakdown region that we seen above. It means it actually starts to work when the applied voltage is higher than the Zener voltage is in reversed biased.
  • When Zener diode is forward bias, the Zener diode behaves exactly like the normal silicone diode. It conducts with the same 0.7 V voltage drop that accompanies the use of the normal diode.
  • This diode is mostly used in applications involving, voltage regulations, clipping circuits, and voltage shifters.