A power management system for a digital processing core of a battery-powered hearing aid is adapted for providing power to the hearing aid circuit in a particularly efficient manner. The power management system comprises a first linear voltage regulator, and a second linear voltage regulator in series with a switched-capacitor 2:1 SC converter, a positive bulk biasing voltage supply, and a negative bulk biasing voltage supply, for controlling the switching speed, threshold voltage, and current leak from the semiconductor elements of the digital processing core when the core is operated at the reduced voltage provided by the power management system. The power management system may save between 50% and 70% of the power consumed by the digital processing core of the hearing aid circuit. The invention further provides a method for providing a supply voltage to a digital hearing aid.