How do Zener diodes operation?
Zener diode is a kind of pn junction diode. When a reverse bias is applied to a pn junction diode and this reverse voltage is increased, the current increases sharply at a certain voltage (Zener voltage/breakdown voltage). A Zener diode is a diode that generates a constant voltage using this characteristic.
In general, pn junction diodes, this breakdown voltage is several tens of volts or more, but Zener diodes are products with a zener voltage of several volts to several tens of volts due to optimization of the impurity concentration of the pn junction.
In the Zener diode's breakdown region, the current increases due to two types of breakdown phenomena:
- Zener breakdown phenomenon: dominant in Zener diodes with Zener voltages lower than 5 V
- Avalanche breakdown phenomenon: dominant in Zener diodes with Zener voltages higher than 5 V
Zener diodes are used in the breakdown region above the Zener voltage. Zener diodes are used in constant voltage applications by operating in this region.
Recently, this property has been used for ESD (electrostatic discharge) protection.
Be careful not to exceed the absolute maximum ratings such as allowable dissipation values described in technical data.
Zener breakdown and avalanche breakdown are also explained in the following FAQ.
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