A Zener diode is a type of diode that permits current to flow in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger than the breakdown voltage known as "Zener knee voltage" or "Zener voltage." Zener diodes are widely used to regulate the voltage across a circuit. When connected in parallel with a variable voltage source so that it is reverse biased, a zener diode conducts when the voltage reaches the diode's reverse breakdown voltage. From that point it keeps the voltage at that value.
These devices are a low-cost solution for guarding against the effects of electrostatic discharge(ESD) in electronic systems and help original equipment designers comply with IEC 61000 4-2 specifications in many subassemblies worldwide. You can learn more about our range of Zener diode products by viewing series guide.