A Practical Model and a New Transient Performance Measurement of Capacitors for VR Applications

This paper presents more exact model and practical measurement method of capacitors for voltage regulator (VR) applications. A simple two-stage RC ladder model of the capacitor is introduced and each parameter is extracted in a time domain measurement by employing a large dc discharge current with high current slew rate during switching. Based on the equivalent ladder model, the capacitance and equivalent series resistance of the capacitor are evaluated as a function of time. Furthermore, simulated results of the transient voltages of the buck converter for large step change of the load current are compared both to proposed model and conventional three components one.