A complete analytical switching loss model for power MOSFETs in low voltage converters

This paper presents a complete analytical switching loss model for power MOSFETs in low voltage switching converters. Traditionally, the piecewise linear model has been used to obtain both switching losses and efficiency in these converters, due to its simplicity and good performance. However, the use of the latest low voltage power MOSFET generations and the continuous increase of the switching frequencies have made necessary to review this model to account for the parasitic inductances that were not included into it. The switching loss model presented in this paper includes all the parasitic inductances; it clarifies the switching process and provides information about how these inductances determine the switching behavior and the final converter efficiency. The analysis presented in this paper also yields two different types of possible switching situations: capacitive-determined switching and inductive-determined switching. In the former the piecewise linear model can be applied, while in the latter the proposed model is more accurate. Carefully-obtained experimental results that will be described in detail support the analytical results presented.