The characteristic of the Zener diode is that after breakdown, the voltage at both ends remains basically unchanged. When the voltage regulator tube is connected to the circuit, if the voltage of each point in the circuit fluctuates due to fluctuations in the power supply voltage or other reasons, the voltage across the load will remain unchanged.
The Zener diode works by using the voltage stabilization characteristic of reverse strike multi-zone, therefore, the Zener diode should be connected in the reverse direction in the circuit. The reverse breakdown voltage of a Zener diode is called a stable voltage, and the stable voltage of different types of Zener diodes is different. The voltage regulation value of a certain type of Zener diode is fixed within the specified range. For example: the voltage regulation value of 2CW11 is 3.2V to 4.5V, and the voltage regulation value of one tube may be 3.5V, and the other tube may be 4.2V.
The dynamic resistance of the Zener diode changes with the operating current, the greater the operating current. The smaller the dynamic resistance. Therefore, in order to achieve a good voltage stabilization effect, the operating current must be selected appropriately. Choosing a larger working current can reduce the dynamic resistance, but it cannot exceed the maximum allowable current (or maximum power dissipation) of the tube.
The stability of the Zener diode is affected by temperature. When the temperature changes, the stable voltage of the Zener diode will also change. The temperature coefficient of the stable voltage is often used to express this performance. For example, the stable voltage of the 2CW19 Zener tube Uw= 12V , The temperature coefficient is 0.095% ℃, indicating that every 1 ℃ increase in temperature, its stable voltage increases by 11.4 millivolts. In order to improve the stable performance of the circuit, appropriate temperature compensation measures are often adopted. When the stability performance is very high, a stable voltage with temperature compensation is required, such as 2DW7A, 2DW7W, 2DW7C, etc.
Unlike other ordinary diodes, the reverse breakdown of Zener diodes is reversible. When the reverse voltage regulator tube is removed, the Zener diode returns to normal. However, if the reverse current exceeds the allowable range, the diode will heat and break down. The resistor often acts as a current limiter.
The above explanation is about the characteristics and performance of Zener diodes. I hope it will be helpful to you after reading. 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!