Zener diode as a voltage regulator:
A Zener diode working in the breakdown region can serve as a voltage regulator. It maintains a constant output voltage even when input voltage Vi or load current IL varies. Here, in this circuit the input voltage Vi is regulated at a constant voltage, Vz (Zener voltage) at the output represented as V0 using a Zener diode.
The output voltage is maintained constant as long as the input voltage does not fall below Vz
.
When the potential developed across the diode is greater than Vz ,the diode moves into the Zener breakdown region. It conducts and draws relatively large current through the series resistance Ri . The total current I passing through Ri equals the sum of diode current IL (I = IZ + IL ) It is to be noted that the total current is always less than the maximum Zener diode current.
Under all conditions V0 = Vz Thus, output voltage is regulated.
