What is the primary function of a Zener diode?

The primary function of a Zener diode is to regulate voltage by allowing reverse current flow. When a Zener diode is reverse-biased, it maintains a stable and constant voltage across its terminals, known as the Zener voltage, as long as the current flowing through it remains within specified limits. This property makes Zener diodes particularly useful in voltage regulation applications, as they can provide a fixed reference voltage and help maintain it despite changes in load conditions or input voltage fluctuations.

In contrast, amplifying current in one direction is a characteristic of standard diodes but not Zener diodes, which are primarily used for their voltage regulation capabilities. Storing electrical energy is a function more associated with capacitors, while converting analog signals to digital is the function of an analog-to-digital converter (ADC). Thus, the unique ability of Zener diodes to stabilize voltage levels in various circuits is what sets them apart and defines their main purpose.