Zener diode 

Zener diode

A normal p-n junction diode allows electric current only in forward biased conditions. When forward-biased voltage is applied to the p-n junction diode, it allows a large amount of electric current and blocks only a small amount of electric current. Hence, a forward-biased p-n junction diode offers only a small resistance to the electric current.

When reverse-biased voltage is applied to the p-n junction diode, it blocks a large amount of electric current and allows only a small amount of electric current. Hence, a reverse-biased p-n junction diode offers large resistance to the electric current.

If the reverse-biased voltage applied to the p-n junction diode is highly increased, a sudden rise in current occurs. At this point, a small increase in voltage will rapidly increase the electric current. This sudden rise in electric current causes a junction breakdown called Zener or avalanche breakdown. The voltage at which Zener breakdown occurs is called Zener voltage and the sudden increase in current is called Zener current.

A normal p-n junction diode does not operate in the breakdown region because the excess current permanently damages the diode. Normal p-n junction diodes are not designed to operate in the reverse breakdown regions. Therefore, a normal p-n junction diode does not operate in the reverse breakdown region.

What is Zener diode?

A Zener diode is a special type of device designed to operate in the Zener breakdown region. Zener diodes act like normal p-n junction diodes under forwarding biased conditions. When forward-biased voltage is applied to the Zener diode it allows a large amount of electric current and blocks only a small amount of electric current.

Zener diode is heavily doped than the normal p-n junction diode. Hence, it has a very thin depletion region. Therefore, Zener diodes allow more electric current than the normal p-n junction diodes.

Zener diode allows electric current in forwarding direction like a normal diode but also allows electric current in the reverse direction if the applied reverse voltage is greater than the Zener voltage. Zener diode is always connected in the reverse direction because it is specifically designed to work in the reverse direction.

More Details

Zener diode | Definition, Breakdown

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