Basic Interpretation
Zener diode refers to a diode that uses the reverse breakdown state of the pn junction, and its current can vary in a wide range while the voltage is basically unchanged.
Principle
The forward characteristic of the volt-ampere characteristic curve of the Zener diode is similar to that of an ordinary diode. The reverse characteristic is that when the reverse voltage is lower than the reverse breakdown voltage, the reverse resistance is large and the reverse leakage current is extremely small. However, when the reverse voltage is close to the critical value of the reverse voltage, the reverse current suddenly increases, which is called breakdown. At this critical breakdown point, the reverse resistance suddenly drops to a very small value. Although the current varies in a wide range, the voltage across the diode is basically stable around the breakdown voltage, thus achieving the diode's voltage regulation function.
Fault characteristics
The faults of the Zener diode are mainly manifested in open circuit, short circuit and unstable voltage regulation value. Among these 3 kinds of faults, the former fault shows that the power supply voltage rises; the latter two faults show that the power supply voltage drops to zero volts or the output is unstable.