What is a Zener diode? Application Note of Zener Diode

Zener diode (also called Zener diode or reverse breakdown diode) is a surface contact type crystal diode made of silicon material. After the reverse breakdown of the PN junction, the terminal voltage does not change with the reverse current transformation within a certain range. The housing materials of Zener diodes are mainly glass, plastic and metal. Generally, low-power Zener diodes are packaged in glass or plastic, and high-power Zener diodes are packaged in a metal shell with good heat dissipation. Since Zener diodes are generally made of silicon semiconductor materials, they are also called silicon Zener diodes and silicon Zener tubes.
Since the Zener diode has a voltage stabilizing effect, its technical parameters are roughly the same as those of ordinary diodes. It is widely used in regulated power supplies, electronic igniters, DC level shifting, limiting circuits, overvoltage protection circuits, and compensation circuits. Wait.

1. Stable voltage

This refers to the reverse voltage value at both ends of the diode within the range of its voltage stabilization effect, which is usually written as the voltage stabilization value. The stable voltage value of the Zener diode changes with its operating current and temperature, but this change is not very large. Different types of Zener diodes generally have different stable voltages. Even for products of the same type, the voltage stabilized value may not be exactly the same. You should select them according to your needs when using them.

2. Working current

When the device is working, the reverse basic current that passes through, and the working current of the Zener diode is too small, the voltage regulation effect will be worse, and the current is too large, and the tube body will be damaged due to excessive temperature. Generally, within the allowable working current range, the current is larger, and the voltage stabilizing effect is relatively better, but the voltage stabilizer diode needs a small amount of electric energy. The difference between a Zener diode and an ordinary diode is that its working current flows from the cathode to the anode, while the ordinary diode flows from the anode to the cathode.

3. Maximum working current

The value of the reverse current allowed by the Zener diode.

4. Power dissipation

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 is working, we hope that the stable voltage change should be as small as possible when the current change range is large. In order to accurately reflect this performance, the ratio of the voltage change to the current change is specified as the drive of the Zener diode Resistance, it can be seen that the smaller the dynamic resistance of the Zener diode, the better the performance of the Zener diode. It can be concluded that when the same Zener diode works, the dynamic resistance changes. When the current is large, the dynamic resistance is smaller, and when the working current is small, the dynamic resistance increases instead.

Generally speaking, it is a semiconductor device with high resistance until the critical reverse breakdown voltage. Zener diodes can be connected in series for use at higher voltages, and higher stable voltages can be obtained by connecting them in series.