Special Diodes: Zener Diode

We all use mobile phones

The adapter of the mobile phone gives only 5 volts constantly.

To maintain the voltage constantly, a voltage regulator is used.

A Zener diode is the basic component of a voltage regulator.

Let’s learn about the Zener diode.

Zener diode is a special purpose semiconductor diode.

Symbol of the Zener diode is as above.

Zener diode has 2 terminals namely, 1- Cathode 2- Anode

Let’s see the principle and construction of a Zener diode.

Zener diode is fabricated by combining heavily doped p and n-type semiconductors.

Due to heavy doping, the Depletion region formed is very thin $(\sim 10^{-6}m)$.

The I-V characteristics of Zener diode can be shown as above

It can be seen from the graph that after Voltage Vz, the current rises suddenly in reverse bias mode.

So, For even small changes in voltage, the current varies widely.

And this property of Zener diode is used for regulating supply voltages.

Let’s see how a Zener diode works as a voltage regulator.

To get a constant DC voltage from the unregulated output of the rectifier, we use a Zener diode.

And when the voltage crosses breakdown voltage $V_z$, voltage starts to saturate even if current changes.

So, for any change in current, the voltage across Zener remains the same.

Hence, Zener diode acts as a voltage regulator.

Zener Diode is used to operate in the reverse-bias condition.

Revision

Zener diode is a special purpose semiconductor diode.

Zener diode is fabricated by combining heavily doped p and n-type semiconductors.

Zener diode in reverse bias works as a voltage regulator.

The End