Powering a circuit by alternating power supply connections in series and parallel with a storage capacitor

摘要

An integrated circuit (IC) having an internal power supply voltage step down circuit provides efficiency while requiring a minimum of external terminals. In a first operating mode, a storage capacitor is charged from the power supply return of a group of circuits, while the group of circuits is powered from an input power supply voltage provided to the IC. In a second operating mode, the group of circuits is powered from the storage capacitor. The step-down circuit provides for halving the input power supply voltage, but multiple storage capacitors and additional operating modes can be provided for voltage division by greater factors. A sensing circuit can be employed to sense the voltage across the storage capacitor(s) and in response, select the operating mode, providing hysteretic control of the voltage supplied to the group of circuits.