Zener diodes are widely used in many circuits, such as regulated power supplies, electronic igniters, DC level converters, limiter circuits, overvoltage protection circuits, compensation circuits, etc. Because it has a stabilizing effect.
The parameters of the Zener diode are as follows:
Stable voltage Uz: The voltage value when the zener diode works stably after reverse breakdown is called the stable voltage.
Stable current Iz: The reverse current when the Zener diode works stably after reverse breakdown 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 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 the voltage change △Uz to the current change △I is called the dynamic resistance. The smaller the dynamic resistance, the better the Zener performance.
Rated power consumption Pz: 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.
Temperature coefficient α: The temperature change of the Zener diode will cause a small change in the stable voltage, so the relative change in the voltage across the tube caused by a temperature change of 1°C is the temperature coefficient. The smaller the temperature coefficient, the better, indicating that the Zener diode is less affected by temperature.
Zener diode is a silicon planar contact diode manufactured by alloy method or diffusion method. Its structure is the same as the rectifier diode. It has the unidirectional conductivity characteristics of ordinary diodes, that is, when a DC voltage is applied, the diode conducts, and a large forward current flows through the pole tube. 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 suddenly increase. At this time, the Zener diode enters the breakdown area, and its internal resistance is very small. When the reverse current changes in a large range, the reverse voltage across the diode can remain unchanged, which is equivalent to a constant voltage source.