Stacking Isolated SC Cores for High-Voltage Wide Input Range Monolithic DC-DC Conversion

A fully integrated DC-DC converter that uses isolated switched-capacitor (SC) cores in a stacked way is presented. The converter can transform a wide input voltage range from 7.5 up to 42 V by the multiple available voltage conversion ratios (VCRs), which are realized through reconfiguration of the stackable cores. In addition, stacking simplifies the design to the low-voltage isolated SC core. Level shifters are included to fulfill the high-voltage interfaces, while bulk biasing circuits ensure the correct driving of the switches in the cores. As such, the power converter is implemented in a 0.35-mu m CMOS technology and produces a stable 3-V output with less than 5% voltage ripple for a peak output power of 2.1 mW.