Application Note AN-1001

A More Realistic Characterization of Power

MOSFET Output Capacitance Coss

Table of Contents

1. Introduction .....................................................................................................1

Power MOSFETs and switching frequency ................................................1

Hard switching and power dissipation ........................................................1

Coss effective.............................................................................................1

Coss at 80% Vdss......................................................................................2

2. Summary & Conclusion .................................................................................3

Previously, energy loss through output capacitance in MOSFETs has been deemed insignificant.

However, as frequency increases, and application topologies change, this capacitance becomes

more important. This paper shows a meaningful way to calculate this parameter and how it

contributes to energy loss.