Patent ID: 7468599
Filing Date: 2008-12-23
Classification: H02M

Abstract:
1. A DC (direct current) power supply configured to apply a DC voltage to an output terminal, said DC voltage being output from a system switched selectively between two systems, wherein at least one of said two systems comprises a switching regulator comprising: a first switching element and an inductor serially connected between an input terminal for receiving an input voltage and an output terminal; a second switching element for use in synchronous rectification connected between said first switching element and the ground, wherein said switching regulator is configured to convert the input voltage to a predetermined voltage by releasing energy, that is stored in the inductor during on-period of said first switching element, during off-period of said first switching element by way of said second switching element for use in synchronous rectification, and to output the predetermined voltage such that said second switching element is kept turned off until said first switching element is turned on when an operation of said switching regulator is initiated; a first drive circuit for driving said first switching element; a second drive circuit for driving said second switching element, said second drive circuit coupled to said first drive circuit; and a control circuit for controlling said first and second drive circuits, wherein said control circuit is configured to output a first control signal to said first and second drive circuits, and to assume a control based on the first control signal such that said second switching element is kept turned off until said first switching element is turned on partially based on a signal received by said second drive circuit from said first drive circuit when an operation of said switching regulator is initiated.