Guide to MOSFET Power Dissipation Calculation in High-Power Supply

Abstract: Power MOSFETs are an integral part of any high-power-switching power supplies used in portable devices. Additionally, these MOSFETs are difficult components to specify for notebook products with minimal heat dissipation capabilities. This article provides step-by-step instructions for calculating the power dissipation of these MOSFETs and determining the temperature at which they operate. It then illustrates these concepts by stepping through the design of one 30A phase of a multiphase, synchronous-rectified, step-down CPU core supply.