Switched-capacitor (SC) DC-DC converter with fine tune control outputs

A switched-capacitor (SC) converter is in the spotlight as a coilless converter that consists of capacitors and switches. The SC converters have a weak point that the voltage ratio cannot change linearly, because the output voltage is determined by the voltage dividing ratios of the capacitors. In this paper, we propose SC DC-DC converter with fine tune control outputs. This circuit consists of 2 converter blocks. The output voltage with fine tune control can be obtained by the sum of the output of each converter. Thus, the proposed circuit can provide more numbers of output voltages than conventional converters. As an example, the circuit which has 25 types of outputs in the range 0.75 ~ 2.3V from 3.6V input is designed. The SPICE simulations show that the power efficiency is 85 ~ 70% when the output current is about 160 to 360mA