What is a high-power Darlington tube ( module )?

What is a high-power Darlington tube ( module )?

The high-power Darlington tube is internally connected with a protective device,and the internal structure of the high-power Darlington tube is shown in Figure.It can be seen from the diagram that this kind of pipe reverses between C and E and connects with an over-voltage protection relay diode VD,when the inductive load ( such as relay coil ) is suddenly cut off when the reverse peak voltage is released by VD,the internal transistor is protected from breakdown. In addition, the transistors VTj,VT2 and the emitter junction are also resistors R1 and R2 respectively. The role of R1 and R2 is to provide a drain branch for the leakage current.Thus,it is called a discharge resistor.Because the base leakage current of VT1 is relatively small,the resistance of R1 is usually larger; the leakage current of VT is amplified and added to the base of VT2,plus the leakage current of VT2 itself,which makes the base leakage current of VT2 relatively large, therefore,the resistance value of R2 is usually small.When designing high power Darlington tubes,R1 usually takes several thousand euros,while R2 takes dozens of ohm.

How to detect a high power Darlington tube?

First,the electrodes are distinguished according to the method of measuring the ordinary tube,then the following criteria are judged

The resistance value of the PN junction between B and C is measured with the multimeter RX10k2,the unidirectional conductivity should be clearly measured.There should be a big difference between the positive and negative resistance values.

There are two PN junctions between the high power Darlington tube B and E,and the resistance R is connected; and R2.When using the multimeter to block the detection,when forward measurement,the measured resistance is the forward resistance value and R;the result of parallel connection of R2;when the reverse measurement is reversed,the sum of ( R1 + R2 ) resistance is measured as the sum of ( R1 + R2 ) resistance,which is about several thousand ohms,and the resistance is fixed and does not change with the transformation of the electric barrier variable.But it should be noted that some high-power Darlington tubes in R1,R2 are also respectively and there are diodes,so when the B,E plus the reverse voltage ( that is, the red pen B ), when the black stylus meets E, it is not the sum of ( R1 + R2 ),but ( R ); + R2 ) Shunt resistance with the sum of forward resistance of two diodes.The method of detecting the amplification capability of the high-power Darlington transistor is the same as that of the ordinary Darlington transistor.