Zener Diode as Regulator

Line Regulation with Zener Regulator

• Zener regulator under varying input voltage condition

• It can be seen the input is
1. Vo=Vzis constant
2. IL = Vo/Rl = Vz/Rl = constant
3. And I = Iz+IL
• Now If Vin increases, than the total current I increases. But IL is constant as Vz is constant as Vz in constant. Hence the current Iz increases to keep IL constant
• But as long as Iz is between Izmin and Izmax, the Vz i.e output voltage Vo is constant
• Thus the changes in input voltage get compensated and output is maintained constant.
• Similarly if Vin decreases, than current I decreases. But to keep IL constant, Iz decreases. As long as Iz is between Izmax and Izmin the output voltage remains constant.
• the maximum power dissipation for the zener diode is fixed and given by
1. Pd = VzIz max