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The main parameters of high voltage rectifier diodes and the method of detecting high voltage rectifier diodes

In almost all electronic circuits, semiconductor diodes are used. It plays an important role in many circuits. It is one of the earliest semiconductor devices, and its applications are also very extensive. How much do you know about high voltage rectifier diodes? High-voltage rectifier diode series products are high-voltage rectifier devices composed of multiple micro-unit PN junction chips doped with special metals, using a combination of unique technology and embedded heat dissipation patented technology, to achieve a layered unit structure that can withstand high voltage and high current. What are the main parameters of high voltage rectifier diodes? How to detect the quality of high voltage rectifier diodes?

Main parameters of high voltage rectifier diodes:

1. Maximum average rectified current IF: refers to the maximum forward average current allowed to pass through the diode during long-term operation. This current is determined by the junction area of the PN junction and heat dissipation conditions. When using, it should be noted that the average current through the diode cannot be greater than this value, and the heat dissipation conditions must be met. For example, a 1N4000 series diode has an IF of 1A.

2. The highest reverse operating voltage VR: refers to the maximum reverse voltage allowed to be applied across the diode. If it is greater than this value, the reverse current (IR) will increase sharply, and the unidirectional conductivity of the diode will be destroyed, causing reverse breakdown. Usually half of the reverse breakdown voltage (VB) is taken as (VR). For example, the VR of 1N4001 is 50V, 1N4002-1n4006 are 100V, 200V, 400V, 600V and 800V respectively, and the VR of 1N4007 is 1000V

3. Maximum reverse current IR: It is the reverse current that the diode is allowed to flow under the highest reverse working voltage. This parameter reflects the quality of the diode's unidirectional conductivity. Therefore, the smaller the current value, the better the quality of the diode.

4. Breakdown voltage VB: refers to the voltage value at the sharp bending point of the reverse volt-ampere characteristic curve of the diode. When the reverse is a soft characteristic, it refers to the voltage value under the given reverse leakage current condition.

5. Maximum operating frequency fm: It is the highest operating frequency of the diode under normal conditions. It is mainly determined by the junction capacitance and diffusion capacitance of the PN junction. If the operating frequency exceeds fm, the unidirectional conductivity of the diode will not be well reflected. For example the fm of a 1N4000 series diode is 6.3kHz. Another fast recovery diode is used for the rectification of high frequency alternating current, such as switching power supply.

Reverse recovery time trr: refers to the reverse recovery time under the specified load, forward current and maximum reverse transient voltage.

6. Zero bias capacitance CO: refers to the sum of the diffusion capacitance and junction capacitance when the voltage across the diode is zero. It is worth noting that due to the limitation of the manufacturing process, even the diodes of the same type have great dispersion in their parameters. The parameters given in the manual are often in a range. If the test conditions change, the corresponding parameters will also change. For example, the IR of the 1N5200 series silicon plastic rectifier diodes measured at 25°C is less than 10uA, and at 100°C IR becomes less than 500uA.

The method of using a multimeter to detect the quality of a high-voltage rectifier diode is as follows:

1. To measure with a diode gear or a high resistance gear (10k), it should be conductive or able to measure resistance. The series resistance of the reverse high-voltage rectifier diode is connected to the rectifier diode to allow high voltage tolerance, and the resistance voltage is measured with a multimeter.

2. A rectifier diode is a semiconductor device that converts AC power into DC power. Usually it consists of a PN junction with two terminals, positive and negative. The most important characteristic of a diode is unidirectional conductivity. In the circuit, current can only flow in from the positive terminal of the diode and flow out from the negative terminal.

In the forward direction, use a diode file or a high-impedance file (above 10k) to measure. If it is normal, it should be turned on or the resistance can be measured. In the reverse direction, you can connect the high-voltage rectifier diode in series with the resistor and then connect the rectifier diode to the high voltage that the rectifier diode is allowed to withstand. Use a multimeter to measure the resistance. Whether there is voltage on the upper or lower (that is, whether the diode has a reverse current), if the forward direction can be turned on and the reverse direction is not, it is good, and if there is leakage or breakdown in the reverse direction, it is not good.

Through the above content, everyone has a certain understanding of high-voltage rectifier diodes. When the performance deteriorates, it may cause slow heating or fuse failure. The bidirectional protection diode is just an overvoltage protection device. When the voltage applied to the magnetron is too high for some reason, the protection diode will break down and short circuit, which is equal to the output short circuit of the transformer, the primary current will increase greatly, and the input insurance will be blown, reaching purpose of protection.