- Voltage regulators are used to achieve constant output voltage.
- Voltage across the Zener diode remains constant equal to Vz (Zener breakdown voltage) when it is reverse biased and operated in zener region of the reverse characteristics.
- This characteristic of zener diode is used for voltage regulation.
- Following diagram 1.2 shows the regulator circuit using Zener diode.
- Vin��� is the unregulated input dc voltage, RC is the resistor used for current limiting and RL�� is the load resistor.
- Since Zener diode is shunted across the load resistor it is called as Zener Shunt Regulator.
- The input voltage should always be higher than the breakdown voltage.
- When
and$ I_Z(MIN) \lt I_z \lt I_Z(MAX) $ constant voltage is obtained across the zener diode equal to the breakdown voltage VZ which is the regulated output voltage.
- Refer to chap 1 question 1 for Zener shunt regulator.
- The change in the load voltage due to the change in input voltage (line voltage) is expressed in terms of a factor called line regulation or the voltage stability factor (SV). SV=ΔVo/ΔVin
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