A Simple Analytical Switching Loss Model for Buck Voltage Regulators

Abstract

In this paper, a simple and accurate analytical switching loss model is proposed for high frequency synchronous buck voltage regulators. The proposed model uses simple equations to calculate the rise and fall times and uses piecewise linear approximations of the high side MOSFET voltage and current waveforms to allow quick and accurate calculation of switching loss in a synchronous buck voltage regulator. Effects of the common source inductance and other circuit parasitic inductances are included. Spice simulations are used to demonstrate the accuracy of the voltage source driver model operating in a 1 MHz synchronous buck voltage regulator at 12 V input, 1.3 V output. Switching loss was estimated with the proposed model and measured with Spice for load current ranging from 10-30 A, common source inductance ranging from 250-1000 pH, voltage driver supply ranging from 6-12 V.