Hello friends I hope you all are fine; this is the sixth article in the series on introduction basic electronic components. In the previous article I have discussed the basics of the simple PN junction Diode. In this article I will discuss another commonly used electronic component Zener Diode.
Introduction of Zener Diode:
After reading this component the reader will be able to learn about the construction of the Zener Diode, working of the Zener Diode, basic distinction between the Zener diode and simple PN junction diode. I will also include Zener Effect and applications of the Zener Diode.
What is Zener Diode:
The Zener diode is a special type of simple PN Junction Diode. This type of diode acts the same way as the PN junction diode that is it allows the current to flow in one direction and inhibits its flow in the opposite direction. However the Zener diode is optimized in order to be used as the voltage reference or the voltage regulator. Due to the comparatively heavily doped PN junction an effect called Zener Effect arises in the Zener Diode and results in the Zener breakdown. The Zener diode and its schematic symbol are as shown in the following image:
Zener Diode Definition:
The difference between the Zener diode and simple PN junction diode and the area of application of the Zener diode will be pointed out later in the article. The PN junction of simple PN junction diode can be optimized to form other types of diodes some of the commercially available diodes are;
- Schottky Diode.
- Varactor Diode.
- Tunnel Diode.
- Solar Cell.
- Avalanche Diode.
I will discuss each in the upcoming articles.
When a highly doped PN Junction is reversed biased the tunnel is formed at the breakdown voltage through which the electrons are exchanged across the junction. This effect called the Zener Effect was discovered by Clarence Melvin Zener.
The Zener Diode undergoes the Zener breakdown which is a controlled breakdown and is due to the Zener Effect. Most of the time the Zener Diode is used in the reverse bias so that when the Zener voltage is achieved the Zener diode regulates the input voltage. The Zener voltage is defined as the voltage at which the breakdown of the Zener Diodes occurs.
The Zener breakdown in the Zener diodes is prominent up to 5.6 volts after which the breakdown in the diodes is the combination of both Zener Breakdown and Avalanche breakdown and even after that the breakdown is only Avalanche type.
Construction of Zener Diode:
The basic construction of the Zener Diode is not different from the simple PN junction diode in a way that both diodes have an N-Region and P-Region and a PN junction. The only difference is that the Zener Diode is more heavily doped as compared to the simple PN junction diode and it is the reason why the Zener Diode exhibits Zener Effect. The basic construction of the Zener Diode is as shown in the following figure:
As pointed out earlier that the Zener Diode is usually employed in the reverse biased conditions so when the Zener voltage is achieved the voltage drop across the Zener Diode becomes equal to the Zener Voltage. At this point any increase in the input voltage would not cause any significant effect on the output voltage due to steep curve in the reverse bias condition. Due to this the Zener Diode is used in the voltage regulation.
The voltage-current characteristic of the Zener diode is as shown in the following image:
Although the Zener diode can be employed in the low power Ac to Dc converter but the specialized applications of the Zener diode are:
- Zener Diode is used as the voltage regulator.
- Zener diode is used to provide precise voltage reference.
I hope this article would be helpful for you, I have discussed the working and construction of Zener Diode that is all for now. In the next article I will come up with more interesting application in electrical engineering. Till then stay connected, keep reading and enjoy learning.