On the use of current control scheme for switched-capacitor DC/DC converters

This paper presents an investigation into the use of a current control scheme (CCS) and a comparison with a classical switching scheme for switched-capacitor (SC) step-down dc/dc converters. With the CCS, capacitors are charged with near-constant current, controlled by the gate-source voltage of MOSFET's. By paralleling two SC cells, the converter input current becomes continuous, resulting in much reduced conducted electromagnetic interference with other circuits fed by the same power supply. All MOSFET's are operated for half of the switching period, in order to improve the regulation capability. Static and dynamic behaviors of the converter with the CCS are predicted and confirmed in an experimental 36-W 12-V/9-V prototype.