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Fast recovery diode module (FRD) is a semiconductor diode with good switching characteristics and short reverse recovery time. It is mainly used in electronic circuits such as switching power supply, PWM pulse width modulator and frequency converter. It is used as high-frequency rectifier diode, freewheeling diode or damping diode. The internal structure of fast recovery diode module is different from ordinary PN junction diode. It belongs to pin junction diode Tube, that is, a base region I is added between p-type silicon material and n-type silicon material to form a pin silicon wafer. Because the base region is very thin and the reverse recovery charge is very small, the reverse recovery time of the fast recovery diode module is short, the forward voltage drop is low and the reverse breakdown voltage (withstand voltage value) is high.

Working principle of fast recovery diode module

The internal structure of the fast recovery diode module is to add base region I between p-type silicon material and n-type silicon material to form pin silicon wafer. Because the base region is very thin and the reverse recovery charge is very small, not only the TRR value is greatly reduced, but also the transient forward voltage drop is reduced, so that the tube can withstand a high reverse working voltage.

The reverse recovery time of fast recovery diode module is generally hundreds of nanoseconds, the forward voltage drop is about 0.6V, the forward current is several amperes to several thousand amperes, and the reverse peak voltage can reach hundreds to several thousand volts. The reverse recovery charge of ultrafast recovery diode module is further reduced, so that its TRR can be as low as tens of nanoseconds. Most of the fast recovery and ultrafast recovery diode modules below 20A are in the form of TO-220 package.

When negative voltage (or zero bias voltage) is applied, the fast recovery diode module is equivalent to capacitance + resistance; when positive voltage is applied, the fast recovery diode module is equivalent to small resistance. By changing the structure size and selecting the parameters of the fast recovery diode module, the reflection phase of the short-circuit stepped ridge waveguide is reduced (reference phase) is the same as the reflection phase of the short-circuit waveguide controlled by the pin tube with positive voltage. It is also required that the reflection phase of the short-circuit waveguide controlled by the fast recovery diode module with negative voltage (or 0 bias) is opposite to the standard phase (- 164 ° ~ + 164 °).

Function of fast recovery diode module (in DC circuit)

The fast recovery diode module has the characteristics of high voltage resistance, low leakage current during reverse blocking, low on state resistance and high current in the forward direction. Because it is used as a switch, it is generally required to have a fast switching speed. In addition, properly selecting the characteristics of freewheeling diode, especially the reverse recovery characteristics, such as reverse recovery time and reverse recovery flexibility, can significantly reduce the power consumption of switching devices, diodes and other circuit elements, and reduce the voltage spikes and electromagnetic interference caused by freewheeling diode, so as to minimize or even remove the absorption circuit.

Generally speaking, the forward voltage drop of the fast recovery diode module is small, about 0.4V, while the common silicon tube is about 0.6V. In order to reduce the loss, the fast recovery diode module is used.

If the reverse breakdown voltage of the fast recovery diode module is 40V, it can recover quickly after reverse breakdown; If the reverse breakdown voltage of the fast recovery diode module is 1000V, there is no problem of reverse breakdown, so this can not be considered in the DC circuit.