A zener diode is a type of semiconductor diode that is designed to operate in the reverse breakdown region of its voltage-current characteristic curve. This means that it can maintain a constant voltage across its terminals, even when the current through it varies. This makes it useful for voltage regulation in electronic circuits.
Zener diodes are typically used in conjunction with a series resistor in a voltage regulator circuit. The resistor limits the current through the diode, while the zener diode maintains a constant voltage across its terminals. This allows the output voltage to remain stable, even when there are changes in the input voltage or load.
The breakdown voltage of a zener diode is the voltage at which it begins to conduct in the reverse direction. This voltage is determined by the doping level and physical dimensions of the diode. Zener diodes are available in a range of breakdown voltages, typically from 2.4V to 200V.
The main advantage of using a zener diode for voltage regulation is its ability to maintain a constant output voltage. It is also relatively inexpensive and easy to use in electronic circuits. However, zener diodes have a limited power-handling capability and may require additional components for proper operation, such as a series resistor or a transistor. They also have a relatively high voltage drop, which can result in power loss.
The breakdown voltage of a zener diode is affected by temperature, with higher temperatures resulting in a lower breakdown voltage. This can impact the accuracy of the voltage regulation. To compensate for this effect, some zener diodes are designed with a temperature-compensating circuit that adjusts the current through the diode to maintain a constant output voltage.