Zener Diode

Zener Diode Characteristics

Let us understand the characteristics of the Zener diode as explained below.

We already know that the Zener diode behaves like a normal diode when connected in the forward bias. However, the reverse voltage increases when we apply the reverse bias to the diode. 

As a result, the reverse voltage goes beyond the set limit. At such a time, the voltage breakdown takes place. This phenomenon is the Zener breakdown. 

Now that the Zener breakdown has taken place, the current starts conducting in the opposite direction. Several disturbances take place, making the graph haphazard. It indicates the points where a diode has a certain resistance. 

Now, we can represent the voltage across the Zener diode as:  

V = VZ + IzRz 

What are the Applications of the Zener Diode? 

The Zener Diode has many applications in the world of physics. As discussed earlier, a Zener regulated power supply serves various purposes. Let us discuss some applications below:  

Zener Diode as a Voltage Stabiliser: 

You may have seen that voltage fluctuations can cause a lot of damage to your electrical and commercial appliances. The simple solution to it all is: using a Zener diode. 

All electrical appliances use Zener diodes as a voltage regulator. It provides a steady and constant voltage from the source. 

Zener Diode for Protection of Metres: 

Accidental overload of electricity can be extremely dangerous. Zener diodes are used in multimeters to prevent such accidents and ensure safety. The connection of the diode to the metre is parallel. 

When an accidental case of overload occurs, the circuit passes on most of the current to the diode. Hence, it doesn’t cause any damage to the metre in a Zener-generated power supply.  

Zener Diode for Wave Shaping: 

The Zener diode is also useful to convert the sine wave into the square wave. Now, you may wonder how? 

You connect the Zener diodes to a series but in opposite directions.  

In a Zener-regulated power supply, the Zener voltage is less than the applied voltage. Consequently, the diode has high resistance.  

When the voltage is more than the Zener voltage, it offers low resistance and the current starts flowing through the diode now. There is a drop of voltage at the resistance and cutoff of the input wave at its peak. Hence, we see the square wave. 

Difference between the Normal Diode and Zener Diode

Typically, diodes allow the flow of current only from anodes to cathodes. But in the case of Zener diodes, the flow of current also takes place from cathodes to anodes. Due to the functionality of these diodes, they are one of the most commonly used semiconductors for various industrial purposes. 

The Zener diode is also widely known as the breakdown diode. It has this name because the Zener diode working is based on the breaking of the circuit when the voltage reaches a point known as the Zener voltage or the knee point. 

At this point, the diode reverses, and the current starts to flow in the reverse direction. This effect is also known as the Zener effect. This type of diode is heavily doped, and we form it mainly to work in the reverse direction. 

The physicist Zener discovered that we could exploit the breakdown effect of the diode to move the electrical current in the opposite direction. And that is what led him to develop the Zener diode.

Conclusion 

Zener Diode is one of the most critical devices in electrical appliances. It finds major applications in all commercial and industrial equipment. Its ability to resist the voltage and prevent damage due to voltage overload works wonders in the case of heavy and costly equipment. 

The application of Zener diodes as a voltage regulator helps stabilise the voltage and ensures a constant flow of voltage across the circuits. This application is due to heavy doping, i.e., impurities, in the diode. 

The application of reverse bias makes the current flow in the opposite direction. That’s how it is used in all the appliances.