Zener diodes are widely used in many circuits due to their stabilizing effect, such as regulated power supplies, electronic ignitors, DC level conversion, limiter circuits, overvoltage protection circuits, compensation circuits, etc. The overvoltage of the Zener diode has overvoltage and undervoltage protection. The Zener diode can prevent the load from being in a low voltage state for a long time and the end of the circuit is disconnected. It uses the breakdown voltage of a Zener diode. Once the power supply voltage VCC exceeds the breakdown voltage of the Zener diode, the Zener diode will be turned on. At this time, the contact K is closed, the relay is turned on, and the load R1 works. When the VCC voltage is too low (not reaching the stable voltage value of the Zener diode), the contact does not act and the relay does not close.
Generally speaking, Zener diode has five main parameters, namely stable voltage, stable current, dynamic resistance, rated power consumption and temperature coefficient. The stable voltage refers to the voltage value when the Zener diode works stably after the reverse breakdown, which is called the stable voltage. After the reverse breakdown, the reverse current when the Zener diode works stably is called the stable current. The maximum reverse current allowed through the Zener diode is called the maximum stable current. When using a Zener diode, the operating current cannot be exceeded, and it is usually designed based on an output voltage greater than 2 times.
When the Zener diode works on the reverse breakdown curve, the ratio of the voltage change Uz to the current change I is called dynamic resistance. The smaller the dynamic resistance, the better the voltage regulation performance. The rated power consumption Pz of the Zener diode is determined by the allowable temperature rise of the chip, and its rated value is the product of the stable voltage Uz and the maximum allowable current Iz. The temperature change of the Zener diode will cause a slight change in the stable voltage, so the relative change in the voltage across the tube caused by the 1°C temperature change is the temperature coefficient. The smaller the temperature coefficient, the better, indicating that the Zener diode is hardly affected by temperature.
Zener diode uses the temperature coefficient of Zener diode in the temperature compensation circuit. In circuits where a complementary Zener diode requires higher voltage stability, especially the influence of temperature on voltage, there are actually two common Zener diodes in this temperature complementary Zener diode. However, their temperature characteristics are opposite. When the temperature rises or falls, the tube voltage drop of one diode decreases, and the tube voltage drop of the other diode increases, so the total tube voltage drop of the two diodes remains unchanged, which plays a role of temperature compensation.
The above explanations are about the parameters and applications of Zener diodes. I hope it will be helpful to you after reading them. If you want to know more about Zener diodes, please contact customer service online or call our company's service hotline. (Upper right corner of the website) For consultation, we will be happy to provide you with quality service!