Five important parameters of Zener diode — SUNMATE

Five important parameters of Zener diode

Zener diode is a diode that stabilizes the working voltage of the circuit. Due to the special internal structure characteristics, it is suitable for the working state of reverse breakdown. As long as the current is limited, this breakdown is non-destructive. At this time, although the current passing through the zener diode changes within a large range, the voltage at both ends of the zener diode is almost unchanged and remains stable. Its usage in the circuit is completely different from that of ordinary diodes. It has voltage stabilizing function, and its characteristic is that it has stable terminal voltage during reverse breakdown.

The zener diode works by using the characteristic that the terminal voltage does not change with the reverse current voltage within a certain range after the reverse breakdown of PN junction. It can be seen from the figure below that the shape of Zener diode is similar to that of some ordinary diodes. Its shell materials mainly include glass, plastic and metal. Generally, low-power zener diode is encapsulated in glass or plastic, and high-power zener diode is encapsulated in metal shell with good heat dissipation. As the zener diode is generally made of silicon semiconductor material, it is also called silicon zener diode and silicon zener tube.

Parameter description of Zener diode:

The main purpose of Zener diode is to stabilize voltage, so its technical parameters are roughly the same as those of ordinary diode, mainly including the following 5 points

1. Stable voltage

This refers to the reverse voltage value at both ends of the diode within its voltage stabilizing range, which is usually written as a voltage stabilizing value. The stable voltage value of Zener diode changes with its working current and temperature, but this change is not great. Different types of Zener diodes generally have different stable voltages. Even for products of the same model, the zener value cannot be exactly the same. It should be selected according to needs.

2. Working current

When the device works, the working current of the reverse basic current passing through the zener diode is too small, and the voltage stabilizing effect will become worse. If the current is too large, the tube body will be damaged due to too high temperature. Generally, within the allowable working current range, the current is larger, and the voltage stabilizing effect is relatively better, but the voltage stabilizing diode needs more than a small spoon of electric energy. The difference between zener diode and ordinary diode is that its working current flows from negative to positive, while ordinary diode flows from positive to negative.

3. Working current

The reverse current allowed by the zener diode.

4. Dissipated power

When the reverse current passes through the zener diode, the allowable value of the power consumed by the tube itself is called the rated power. In actual use, the power consumed by the zener diode is not allowed to exceed this limit.

5. Dynamic resistance

When the zener diode works, we hope that the stable voltage change will be as small as possible when the current change range is large. In order to accurately reflect this performance, it is stipulated that the ratio of voltage change to current change is called the driving resistance of the zener diode. It can be seen that the smaller the dynamic resistance of the zener diode, the better the performance of the zener tube. It is concluded that the dynamic resistance changes when the same zener diode works. When the current is large, the dynamic resistance decreases, while when the working current is small, the dynamic resistance increases.