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What is the difference between a fast recovery diode and a super fast recovery diode
Publish：SHENZHEN ENXIC ELECTRONICS CO., LTD,Schottky diodes, rectifier diodes, fast recovery diodes, switching transistors, thermistors, MOS tube, TVS tube, Youze Electronics Time：2017-12-21 Views:1281
Fast recovery diode (fast recovery diode) refers to a diode with short reverse recovery time (below 5us). The process is mostly using gold doping measures, structure with PN junction structure, and some improved PIN structure. The forward voltage drop is higher than that of the ordinary diode (1-2V), and the reverse withstand voltage is mostly below 1200V. From the performance, it can be divided into two levels: fast recovery and ultrafast recovery. Today Xiaobian explains their differences and characteristics.
Characteristic
Structure characteristics of fast recovery and ultra fast recovery diodes
The internal structure of the fast recovery diode is different from that of the ordinary diode. It increases the base area I between the P and N silicon materials, and forms the P-I-N silicon wafer. Because the base area is very thin and the reverse charge is very small, it not only greatly reduces the TRR value, but also reduces the transient forward voltage drop, so that the tube can withstand a very high reverse working voltage. The reverse recovery time of the fast recovery diode is usually hundreds of nanoseconds, the forward voltage drop is about 0.6V, the positive current is several amperes to several thousands amperes, and the reverse peak voltage can reach hundreds to thousands of volts. The reverse recovery charge of the ultra fast recovery diode is further reduced, so that its TRR can be as low as tens of nanoseconds.
Most of the fast recovery and ultra fast recovery diodes below 20A are TO-220 packages. From the perspective of internal structure, it can be divided into two types: single pipe, double tube. There are two fast recovery diodes inside the tube. According to the two diode connection methods, there are two common negative pair pipes and two pairs of positive tube pairs.
application
The fast recovery diode has the advantages of good switching characteristics, short reverse recovery time, large forward current, small volume and easy installation. The ultra fast recovery diode is developed on the basis of fast recovery diode, and its reverse recovery time TRR value is close to the index of Schottky diode. They can be widely used in switching power supply, pulse width modulator (PWM), uninterruptible power supply (UPS), AC motor electronic frequency conversion speed control (VVVF), high frequency heating and so on. It can be used as a high frequency, high current continuous current diode or rectifying tube. It is a promising power and electric sub semiconductor device.
Difference
Fast recovery diode (fast recovery diode) refers to a diode with short reverse recovery time (below 5us). The process is mostly using gold doping measures, structure with PN junction structure, and some improved PIN structure. The forward voltage drop is higher than that of the ordinary diode (1-2V), and the reverse withstand voltage is mostly below 1200V. From the performance, it can be divided into two levels: fast recovery and ultrafast recovery. The reverse recovery time is hundreds of nanoseconds or longer, while the latter is less than 100 nanoseconds.
test method
(1) conventional detection methods
In amateur conditions, using the multimeter can detect the unidirectional conductivity of fast recovery, ultra fast recovery diode, and there is no open circuit and short circuit fault in the interior, and can detect the forward conduction pressure drop. If we have Mega ohmmeter, we can measure the reverse breakdown voltage.
Example: measure a C90-02 ultra fast recovery diode, and its main parameters are trr=35ns, Id=5A, IFSM=50A and VRM=700V. A. The 500 type multimeter is allocated to R * 1 files, and the forward resistance is 6.4 ohm, n ‘=19.5 lattice, and the reverse resistance is infinite. The VF=0.03V/ lattice x 19.5=0.585V is further obtained. It proves that the pipe is good.
(2) measurement of reverse recovery time
The measurement circuit is illustrated as follows. By the DC current source for the specified IF, the pulse generator, through the direct capacitor C and the pulse signal, uses the electronic oscilloscope to observe the TRR value, that is, the time from the time of I=0 to the IR=Irr time.
The reverse charge within the device is Qrr.
TRR = 2Qrr/IRM (5.3.1)
According to formula (5.3.1), when IRM is fixed, the smaller the reverse recovery charge is, the shorter the reverse recovery time is.
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