Investigation of the steady-state and dynamic characteristics of a buck converter with nonlinear output capacitor current programming

A detailed steady-state and dynamic analysis of a buck converter with nonlinear output capacitor current programming is presented. The advantages of the proposed method are its constant switching frequency operation, simplicity in implementing the switching functions and designing the control parameters, good steady-state and dynamic responses, and high audio susceptibility rejection. The principle of operation and all possible operating cases will be described and discussed. With the inclusion of the effects of the equivalent series resistance (ESR) of the output capacitor, the steady-state output characteristics and small-signal models for studying the system stability will be derived. An experimental prototype of a 25 W, 12 V/5 V buck converter has been built and evaluated.