Patent ID: 7795848

Claim:
A power supply circuit for receiving an input voltage and generating a first output voltage and a second output voltage, the power supply circuit comprising: a regulator for generating the first output voltage from the input voltage; a first switch circuit, connected to the regulator, for selectively outputting the first output voltage as the second output voltage; and a pre-charge circuit, connected to the regulator and the first switch circuit, for generating the second output voltage from the input voltage before the first output voltage is output as the second output voltage while controlling the first switch circuit, wherein the pre-charge circuit includes, a pre-charge path for outputting the input voltage as the second output voltage, a second switch circuit arranged in the pre-charge path for selectively activating the pre-charge path, and a logic circuit, activated by an enable signal, for generating first and second control signals that activate and inactivate the first and second switch circuits in a complementary manner, and wherein the second switch is activated in response to the enable signal and deactivated in response to the second control signal after the second output voltage reaches a level that is substantially the same as the first output voltage.