Design of a Step-Down Switched-Capacitor DC-DC Converter with Charge-Average Processes

A step-down DC-DC converter with charge-average processes is proposed in this paper. The converter is designed by using switched-capacitor (SC) techniques. Different from conventional converters such as a series-parallel type power converter and a Dickson-type power converter, the ripple noise of the proposed converter is small, because the output voltage is always obtained irrespective of the states of the clock pulses. The output voltage of the proposed converter is expressed by (Q/P) × Vin (P ∈{1, 2,..., N} and Q∈{1, 2,..., N}). Furthermore, when the number of the capacitors is small, the hardware-cost for the proposed circuit is less than that for the conventional converters such as a series-parallel type power converter and a ring-type power converter. Concerning 3-stage power converters, SPICE simulations are performed to confirm the validity of the circuit design. For the input voltage 3.6 V, the power efficiency of the proposed circuit is 92.7 % in the output current about 320 mA.