Design Considerations of Step-Down Switching Converters

To obtain the design method of inductance and capacitance of a step-down switching converter, its Output Voltage Ripple (OVR) in CCM and DCM is analyzed. The Maximum OVR(MOVR) in each operating region is obtained, respectively. It is pointed out that the minimum inductance to guarantee the lowest OVR is the critical inductance of CCM and DCM under the highest input voltage and heaviest load. The design method of inductance and capacitance is proposed according to the desired OVR level within the total operating range. The analysis and feasibility of the proposed method are verified by the experiment results.