US Patent 7949886 Power supply system for motherboard

An exemplary power supply system and method for a motherboard includes a power circuit providing power for a south bridge, and a controller having first and second transistors. An input terminal of the power circuit is connected to a power supply. An output terminal of the power circuit is connected to a reset pin of the south bridge. A first terminal of the first transistor is configured for receiving a control signal from the south bridge. A second terminal of the first transistor is connected to a first terminal of the second transistor. A second terminal of the second transistor is connected to the reset pin of the south bridge. Each of the first and second transistors has a third terminal grounded.