Zener diode is a heavily doped semiconductor diode which is designed to operate in reverse direction. It is widely used as a voltage regulator.
When the reverse bias on a normal diode is increased, the breakdown voltage is reached. Thus, the reverse current increases sharply to a high value.
The breakdown region is the knee of the reverse bias.
It is also called Zener voltage and the sudden increase in current is called Zener current.
It depends upon the amount of doping.
Effect of doping
If the diode is heavily doped, depletion layer will be thin.
Hence, the breakdown of the junction will occur at a lower reverse voltage.
On the other hand, a lightly doped diode has a higher breakdown voltage.
When forward biased, it behaves similar to normal PN diode.
The diode is not instantly burnt just because it has entered the breakdown region.
As long as the external circuit connected to the diode limits,
the diode current to less than burn out value, it will not burn out.
Applications of Zener Diode
- Voltage Regulator
- Meter Protector
Frequently Asked Questions (FAQs)
1.Why is Zener Diode used a regulator?
It is connected parallel to the load to make it reverse bias and once it exceeds knee voltage, the voltage across the load becomes constant.
2. What is meant by reverse breakdown?
Sudden increase in reverse current of a p-n junction diode when a definite reverse voltage is applied is called reverse breakdown.
Also read >> Types of transistors