11.5 A 21W 94.8%-Efficient Reconfigurable Single-Inductor Multi-Stage Hybrid DC-DC Converter

The ongoing demand for smaller form factors and faster charging times of mobile products continue to drive the need for efficient, high-density power delivery (PD) for charging with a wide input voltage $(\mathrm{V}_{\text{IN}})$ range of 5V to 20V, offered by USB-C PD. A converter solution that efficiently takes advantage of this wide $\mathrm{V}_{\text{IN}}$ range while providing an output voltage $(\mathrm{V}_{0})$ range suitable for battery charging (2.8V to 4.2V) remains challenging but highly desirable. Hybrid converters and their benefits such as inductor size reduction and small $\mathrm{V}_{0}/\mathrm{V}_{\text{IN}}$ voltage conversion ratios (VCRs) at high efficiency provide a path to meet this challenge. While recent commercial [1] and research works [2]–[4] have demonstrated these benefits, their limited $\mathrm{V}_{\text{IN}}$ or VCR ranges are unable to take full advantage of USB-C PD or have the inductor located at the high output current $(\mathrm{I} _{0})$ path [1]–[3] where DCR conduction losses can become significant for small footprints.