A typical application for Zener diodes is as

• A. voltage regulators
• B. rectifiers
• C. switching diodes
• D. signal diodes

Answer: (A)

Zener diodes are used for voltage regulation because, when reverse-biased to their breakdown voltage, they hold the voltage across them nearly constant over a range of current. In a simple regulator, the Zener is placed in reverse across the output with a series resistor from the input. The Zener clamps the output at its specified Zener voltage, so changes in input or load current cause the Zener current to adjust while the output voltage stays roughly fixed. This makes it a classic voltage regulator or reference in low-power supplies and circuits.

Other diodes serve different roles: rectifiers convert AC to DC, switching diodes are chosen for fast switching, and signal diodes handle small-signal tasks. The Zener’s defining feature is its controlled breakdown voltage for voltage regulation.