Disclosed are multi-stage multilevel DC-DC step-down converters. Stages may include three or four switches, and switches of each stage are operated at selected duty cycles such that each stage reduces an input voltage by one-half and voltage stress on switches is reduced. In some embodiments only a single output inductor is used in an LC filter, and the inductor may be very small as compared with a conventional Buck converter. Thus, embodiments provide DC-DC step-down converters with high power density and efficiency.