Zener diode (also known as zener diode) is a junction silicon semiconductor diode manufactured by special process. The impurity concentration of this tube is relatively large, the charge density in the space charge region is high and narrow, and it is easy to form a strong electric field. When the reverse voltage is applied to a certain value, the reverse current increases sharply, resulting in reverse breakdown,. VZ represents the reverse breakdown voltage, that is, the stable voltage of Zener diode. The voltage regulation principle of Zener diode is that for the reverse breakdown region, when the current changes greatly, only small voltage changes are caused, that is, the voltage is basically unchanged. The steeper the reverse breakdown curve and the smaller the dynamic resistance, the better the voltage regulation performance of Zener diode.

In the regulator voltage regulator circuit, a current limiting resistor R is usually added to make the zener current work within the voltage regulation range of izmax and izmix.