Zener diode as a voltage regulator: A Zener diode working in the break down repin can serve as a voltage regulator. It maintains a constant output voltage even when input voltage `V_1`. or load current `I_L` varies. Here, in this circuit the input voltage `V_i` is regulated at a constant voltage. `V_z`. (Zener voltage) at the output represented as Vousing a Zener diode. The output voltage is maintained constant as long as the input voltage does not fall below `V_z`
Circuit to study voltage regulation by Zener diode
When the potential developed across the diode is greater than `V_z` the diode moves into the Zener breakdown region. It conducts and draws relatively large current through the series resistance `R_i` The total current I passing through Requals the sum of diode currently and load current `I_L(I=I_Z+I_L)`. It is to be noted that the total current is always less than the maximum Zener diode current
Under all conditions `V_o=V_z`
Thus, output voltage is regulated.
