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Identification method of MOS tube and IGBT tube in electronic circuit


MOS tubes and IGBT tubes are new electronic devices with high frequency of use in modern electronic equipment, so they are often encountered in electronic circuits and are accustomed to. However, due to the similarity in appearance and static parameters of MOS tube and IGBT tube, sometimes it is easy to travel in the selection, judgment, and use. The reliable identification method of MOS tube and IGBT tube is to clear the obstacles for selection, judgment and use.


MOS tube is MOSFET, Chinese name is metal oxide semiconductor insulated gate field effect tube. Its characteristics, high input impedance, fast switching speed, good thermal stability, voltage control current and other characteristics.


IGBT Chinese name insulated gate bipolar field effect transistor is a combination of MOS tube and transistor, MOS is used as input tube, and transistor is used as output tube. Therefore, the power of the triode is quite large, so after the combination of the two, the advantages of the MOS tube and the advantages of the transistor are obtained.


To sum up, the two transistors mentioned above are electronic components that are frequently used in electronic equipment at present. They are very similar in appearance and static parameters. Some electronic products have a technological monopoly, and sometimes their models are used in circuits. Erase, as of now, they have no unified standard for naming standards and models, and the appearance and arrangement of pins are similar, and there is no rule to follow. It has become a roadblock in the maintenance process. How to distinguish and judge has become a necessary means.


Identification of damped NPN IGBT tube and N-channel enhanced MOMS tube The gate position of damped NPN IGBT tube and N-channel enhanced MOMS tube is the same, and the position of C pole of IGBT tube is the same as that of MODS tube. The pole position corresponds, the e pole position of the IGBT tube corresponds to the S pole position of the MODS tube, and the judgment and distinction of their quality can be completed by dynamic and static measurement methods, as follows.


1. Static measurement to judge the quality of MOS tube and IGBT tube


First, short-circuit the pins of the two tubes to discharge the static electricity. There is a PN connection between the D pole and the S pole of the MOS tube, and the forward conduction is reversed, so there are Rgd=Rgs=Rds=infinity, Rsd=several thousand ohms . The resistance from the G pole to the c and e poles of the IGBT tube should be infinite, that is, Rgc=Rge=infinity, and there is a damping diode between the IGBT tubes, so it has a unidirectional conduction reverse cut-off characteristic, that is, Rce=infinity, Rec = several thousand ohms. From here, you can only judge the quality of the tube with the resistance gear of the multimeter, but you cannot distinguish which kind of tube it is. If the measured resistance value is small, it means that the tube is broken down, and if the measured resistance value is large, it means that the inside of the tube is broken.


2. Dynamic measurement distinguishes MOS tube and IGBT tube


First, apply a voltage to the gate of the tube with a multimeter, so that the field effect tube establishes a channel, and then measure the resistance between D, S, c, and e, and distinguish the MOS tube and the IGBT tube according to the difference in resistance.


Use the resistance gear of the multimeter to measure the resistance between D, S, c, and e of the two tubes. Since the FET has established a channel, Rds=Rsd≈0, and there is a resistance Rce between Rce, and the transistor is in an amplified state The on-resistance of , Rec is the on-resistance of the internal damping diode, both of which are several thousand ohms. Therefore, according to the measurement, the degree of conduction of the two tubes is different. The resistance value between D and S of the MOS tube is much smaller than the resistance value between the IGBT tubes c and e, so the MOS tube and the IGBT tube can be distinguished.


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