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.