A regulated, power supply system is described using multiphase DC-DC converters with dynamic fast-turnon, slow-turnoff phase shedding, early phase turn-on, and both load-voltage and drive-transistor feedback to pulsewidth modulators to provide fast response to load transients. In an embodiment, a system master can automatically determine whether all, or only some, slave phase units are fully populated. The programmable system includes fault detection with current and voltage sensing, telemetry capability, and automatic shutdown capability. In an embodiment, these are buck-type converters with or without coupled inductors, however some of the embodiments illustrated include boost configurations.