What is the main purpose of a zener diode?

The main purpose of a zener diode is to regulate voltage at a specified level. A zener diode operates in reverse bias and is designed to maintain a constant output voltage, known as the zener voltage, across its terminals when the supply voltage exceeds this level. This characteristic makes zener diodes particularly useful in voltage regulation applications, such as providing a stable reference voltage in power supplies and protecting circuits from overvoltage conditions.

In situations where a circuit requires a consistent voltage level, such as in voltage reference circuits or simple voltage regulators, the zener diode effectively clamps the voltage to its rated level, ensuring that the downstream components receive a stable supply voltage regardless of variations in the input voltage or load conditions. This functionality is crucial for the proper operation of various electronic devices where stable voltage is necessary for reliability and performance.