ZENER DIODE

ZENER DIODE:

 Zener diode is used as a voltage regulator. It provides stable reference at the output and operated always in reversed bias direction. The PN junction is heavily doped to construct the Zener diode, when we diode operated in reversed bias the early breakdown is called Zener breakdown, it’s a normal breakdown  all the application is operated in this breakdown after applying higher voltage then the breakdown changed in avalanche breakdown now in this breakdown the diode then not able to use again. The breakdown as

Zener diode

 AVALANCHE BREAKDOWN:

 In this breakdown the voltage is greater than the Zener voltage and hence it damaged and flow maximum voltage. Once time a diode is operated in avalanche breakdown than it can’t use another time it became useless.

ZENER BREAKDOWN:

Diode can be used again if it operated one time in Zener breakdown, in this breakdown the voltage is less than the avalanche breakdown the application is run in Zener test current region. If we considered that the Zener breakdown is operated in 5V than the avalanche is must greater then 5V. 

ZENER IMPENDENCE:

 The total resistance in a circuit is called impendence

From ohm,

                V=IR

And 

                 R=V/I

Where

                 R=Zz, V=Vz, I=Iz

Hence Zener impendence 

                 Zz=∆Vz/∆Iz  

NUMERIC 1:

A Zener diode exhibit a certain changed in Vz for a certain Changed in Iz on a portion of the linear characteristic curve between Izk and IzM in fig. what is the Zener impendence 

Solution:

              ∆Vz= 50mV

              ∆Iz= 5mA

               Zz=?

Here Zener impendence (Zz)=  ∆Vz/∆Iz 

              Zz= 50mV/5mA

                   = 10Ω