Zener diode
Noun
Meaning
Zener diode (plural Zener diodes)
(electronics) A semiconductor junction device through which current flows normally in the forward direction, and in the reverse direction if a large voltage is applied.
Examples
Although LED forward voltage is far more current-dependent than a Zener diode, Zener diodes with breakdown voltages below 3 V are not widely available.
An exception is when a diode reverse-conducts, either by accident (breakdown of a normal diode) or by design (breakdown of a Zener diode, photo-current of a photodiode).
Diode Light-emitting diode (LED) Photodiode Schottky diode Transient-voltage-suppression diode (TVS) Tunnel diode Varicap Zener diode Typical diode packages in same alignment as diode symbol.
Like a typical diode, there is a fixed anode and cathode in a Zener diode, but it will conduct current in the reverse direction (electrons flow from anode to cathode) if its breakdown voltage or "Zener voltage" is exceeded.
The forward voltage drop (e.g. about 1.7 V for a normal red LED) can be used instead of a Zener diode in low-voltage regulators.
The term Zener diode is colloquially applied to several types of breakdown diodes, but strictly speaking Zener diodes have a breakdown voltage of below 5 volts, whilst avalanche diodes are used for breakdown voltages above that value.