场效应管和电源IC好坏的判断（国外英文资料）.docVIP

场效应管和电源IC好坏的判断（国外英文资料） The field effect tube and the power IC? From left to right, its usually G, D, and S has only three legs. The middle leg D is not an empty leg, which is connected to its heat, and the G is usually triggered in the foot, when the power supply is controlled, the D is the input leg of the power supply, and S is the output. How simple measurement it is good or bad: with digital meter diode red G, black pen to D, let go, with a red pen to D, S black pen, measured by D at this moment, S guide with resistance to a certain extent, conduction, probably around a few to a few hundred Ω. The mechanical table X1 is more visible. And then the three feet of the field tube with the finger, the D, the S, the infinity is off, and the reverse is a small block. These are the VMOS field tubes for NPN. The power IC is measuring whether it controls pulse output (using an oscilloscope), electricity, working conditions, and so on. The best way to do this is by substitution. One: the main parameters of the field effector (1) dc parameters Saturation drain current IDSS it may be defined as: when the voltage between the gate and the source is equal to zero, and leakage, when the voltage is greater than the pinch off voltage between the source and drain current. The clip voltage UP is defined as the UGS required when the UDS must be reduced to a tiny current Open voltage UT is defined as the UGS required when UDS is certain to get the ID to a certain number (2) communication parameters Low frequency cross guide gm is the control effect of the grid and source voltage on the drain current. The capacitance of the electrode capacitance between the electrode capacitors, the smaller the value, the better the performance of the pipe. (3) limit parameters Leakage, source breakdown voltage when the leakage current rapidly increases, the UDS of the avalanche breakdown. Grid breakdown voltage junction field-effect tube work, between gate and the source of p-n junction in the reverse