A Zener Diode
Conventionally, an ordinary diode operated in the reverse breakdown voltage is destroyed due to excessive current but this does not happen to the Zener diode.
A Zener Diode Symbol
A Zener diode is properly doped to reduce/maintain the reverse breakdown voltage, the doping also leads to a very thin depletion layer.
As a result of the very thin depletion layer, a Zener diode has a sharp reverse breakdown voltage, Vz
Reverse Characteristics of a Zener Diode:
Two things occur when Vz is reached which are:
1. The diode current increases rapidly.
2. The reverse voltage, Vz across the diode remains constant.
No matter what the value of current is the Zener voltage is relatively constant. This makes it possible for a Zener diode to be used as a voltage stabilizer.
A Zener diode is always reverse biased as it is always reverse connected, when it is forward biased, it behaves as an ordinary diode.
The Zener diode does not get destroyed once it enters the breakdown region as long as the external circuit connected to the diode limits the diode current to less than burn out value, the diode will not burn out.
If the applied voltage, V is greater than or equal to the Zener voltage, Vz, the Zener diode is in 'ON' state.
If the applied voltage, V is less than the Zener voltage, Vz but greater than zero, the Zener diode is in 'OFF' state.
No comments:
Post a Comment