Abstract: A power supply comprises a transformer having a primary winding, a first switch coupled to the primary winding and to a voltage input, an active clamp circuit coupled in parallel with the primary winding, and a clamp switch control coupled to the active clamp circuit. The power supply further comprises a bootstrap circuit coupled to the clamp switch control and having a bootstrap voltage storage device coupled to the clamp switch control. A charging circuit has a resistor network configured to generate a charge voltage in response to an input voltage supplied by the primary winding. A charge voltage storage device is configured to store at least a portion of the charge voltage during the first portion of the switching cycle and to supply the at least a portion of the charge voltage to the bootstrap voltage storage device during a second portion of the switching cycle.