An inductor in a series path of a DC converter having a buck or boost configuration is constituted by a transformer with windings in series with switches of the converter. A transformer turns ratio facilitates matching switch voltage and current stresses to characteristics of MOSFETs forming the switches. A high side MOSFET can have its source at a constant voltage to facilitate driving this switch. One switch can be replaced by a diode. A transformer leakage energy removal circuit can provide an auxiliary output voltage, greater than the input voltage for a buck configuration.