Collapse effect of field-effect transistors in power applications 1

preface:

The use of field-effect transistors as switching switches has become increasingly common in the design of SMPS (Switching Mode Power Supply) and DC-DC converters. In order to reduce size and improve power density in design, the operating frequency of the power supply is also required to be higher and higher. This will result in a higher di/dt, causing the transient voltage across the drain&source of the field-effect transistors to be more pronounced due to stray inductance effects. Especially at the moment when the power is turned on, the voltage will reach its maximum value. This is due to the fact that the inductance value on the primary side of the transformer is equivalent to the leakage inductance (minimum inductance value) and the output capacitor is completely uncharged. Fortunately, most field-effect transistors can withstand voltage ranges above a certain level, and within this range, designers do not need to add additional protective circuits to avoid unnecessary cost expenditures. This article can lead you to determine the impact on field-effect transistors under what conditions, and help designers measure cost and reliability to achieve the best balance point.