Parameters, Application and structure of Zener Diode

Parameters, Application and structure of Zener Diode.

Zener diodes are widely used in many circuits, such as voltage-stabilized power supply, electronic igniter, DC level converter, limiting circuit, overvoltage protection circuit, compensation circuit and so on. Because it has a stabilizing effect.

The parameters of the Zener diode are as follows:

Stable voltage Uz: the voltage value of the Zener diode when it works stably after reverse breakdown is called stable voltage.

Stable current Iz: after reverse breakdown, the reverse current of the Zener diode working stably is called the steady current. The maximum reverse current allowed to pass through the Zener diode is called the maximum stable current. When using Zener diodes, the working current can not exceed and is usually designed to be more than 2 times the output voltage.

Dynamic resistance Rz: when the Zener diode works on the reverse breakdown curve, the ratio of voltage change Uz to current change I is called dynamic resistance. The smaller the dynamic resistance is, the better the Zener performance is.

Rated power consumption Pz: determined by the allowable temperature rise of the chip, whose rating is the product of the stable voltage Uz and the allowable maximum current Iz.

Temperature coefficient α: the temperature change of the Zener diode will lead to a small change in the stable voltage, so the relative change of the cross-diodee voltage caused by the temperature change of 1 ℃ is the temperature coefficient. The smaller the temperature coefficient, the better, indicating that the Zener diode is less affected by temperature.

Zener diodes are silicon planar contact diodes made by alloy method or diffusion method. Its structure is the same as that of the rectifier diode. It has the unidirectional conductivity of an ordinary diode, that is, when a DC voltage is applied, the diode conducts electricity, and a large forward current flows through the diodee. When a reverse voltage is applied, only a small amount of reverse current flows through the diode. When the reverse voltage reaches a certain level, the reverse current will increase suddenly. At this time, the Zener diode enters the breakdown region, and its internal resistance is very small. When the reverse current varies in a large range, the reverse voltage at both ends of the diode can remain unchanged, which is equivalent to a constant voltage source.