US Patent 7872881 Secondary regulation in a multiple output flyback topology

In one embodiment, a power supply includes a flyback transformer having a primary winding and at least two secondary windings. An output voltage is developed across a first one of the secondary windings. The power supply includes a transistor coupled to the first one of the secondary windings. The output voltage is regulated about a nominal output voltage by operating the transistor in a linear mode when current is flowing through the first one of the secondary windings and by operating the transistor in an off mode when current is not flowing through the first one of the secondary windings.