A 92%-efficiency wide-input-voltage-range switched-capacitor DC-DC converter

The traditional inductor-based buck converter has been the dominant design for step-down switched-mode voltage regulators for decades. Switched-capacitor (SC) DC-DC converters, on the other hand, have traditionally been used in low- power (<;10mW) and low-conversion-ratio (<;4:1) applications where neither regulation nor efficiency is critical. However, a number of SC converter topologies are very effective in their utilization of switches and passive elements, especially in relation to the ever-popular buck converters [1,2,5]. This work encompasses the complete design, fabrication, and test of a CMOS-based switched-capacitor DC-DC converter, addressing the ubiquitous 12 to 1.5V board-mounted point-of-load application. In particular, the circuit developed in this work attains higher efficiency (92% peak, and >;80% over a load range of 5mA to 1A) than surveyed competitive buck converters, while requiring less board area and less costly passive components. The topology and controller enable a wide input voltage (V
_!N
) range of 7.5 to 13.5V with an output voltage (V
_οuτ
) of 1.5V Control techniques based on feedback and feedforward provide tight regulation (30mV
_pp
) under worst-case load-step (1A) conditions. This work shows that SC converters can outperform buck converters, and thus the scope of SC converter applications can and should be expanded.