Zener (SMD)

Introduction of Zener Diode:
Solid state voltage regulator diodes or Zeners have been popular since the late 1950's when they replaced bulky vacuum tubes. Discrete zeners ranging from 500 mW to 5 watts or less have particularly remained a commonly used semiconductor product, despite the evolution of integrated circuits. High power zeners above 5 watts have increasingly been replaced by regulator ICs for power supply outputs, nevertheless power zeners are still used in a variety of areas.

A zener diode is a specially processed single PN junction that provides relatively constant voltage across two terminal despite changes in zener current. Because of this unique characteristic, it is used as a voltage regulator when placed in parallel across a load to be regulated. In special compensated multiple PN junction configurations, it may also be used as a "Zero-TC" reference voltage diode for very small changes in voltage over a wide operating temperature range.