The purpose of a Zener diode is primarily to regulate voltage in electronic circuits. Unlike regular diodes that conduct current in one direction only and block it in the reverse direction, a Zener diode is designed to operate in the reverse breakdown region once a specific voltage, known as the Zener voltage, is reached. This characteristic allows Zener diodes to maintain a constant voltage across their terminals, even when the applied voltage fluctuates, making them useful for voltage regulation and stabilization in various electronic devices and power supplies.
A general-purpose diode and a Zener diode serve different functions in electronic circuits. A general-purpose diode is typically used for rectification purposes, allowing current to flow in one direction only and blocking it in the reverse direction to convert AC (alternating current) to DC (direct current). In contrast, a Zener diode is specifically designed to operate in the reverse breakdown region, where it maintains a constant voltage across its terminals regardless of the current flowing through it. This unique characteristic makes Zener diodes suitable for voltage regulation, voltage reference circuits, surge protection, and other specialized applications requiring precise voltage control.
Zener diodes are always used as voltage regulators in electronic circuits. Their ability to maintain a constant voltage across their terminals, known as the Zener voltage, ensures that the voltage remains stable within a specified range despite variations in the input voltage or changes in load conditions. This makes Zener diodes indispensable for maintaining consistent voltage levels in power supplies, ensuring proper operation of sensitive electronic components and preventing damage due to voltage fluctuations.
Zener diodes are most commonly used in voltage regulation applications where precise and stable voltage levels are required. They are frequently employed in power supplies, voltage reference circuits, voltage clamping circuits, surge protectors, and voltage stabilizers. In power supply designs, Zener diodes are often used in combination with resistors to create voltage reference points or to regulate the output voltage to a desired level. Their reliability, simplicity, and effectiveness in maintaining voltage stability make them essential components in various electronic devices and systems.
The principle of a Zener diode is based on the phenomenon of Zener breakdown or avalanche breakdown. When a Zener diode is reverse-biased and the applied voltage exceeds the Zener voltage (also called the breakdown voltage or knee voltage), the diode enters a state of reverse breakdown. In this region, the Zener diode conducts current heavily and maintains a nearly constant voltage drop across its terminals. This characteristic arises from the internal structure of the Zener diode, which is carefully doped to have a sharp breakdown voltage. The principle of Zener diode operation allows it to regulate voltage effectively and reliably in electronic circuits, making it an essential component for voltage regulation and stabilization applications.