Abstract: A multi-output DC-DC converter is advantageous over the conventional multi-output DC-DC converter in terms of increased power efficiency and power density. The inventive multi-output DC-DC converter is characterized by that the rectifying circuit located at the output stage of the DC-DC converter is implemented by a pair of self-driven synchronous rectifier transistors that can prevent a reverse current from flowing through the switch elements of the DC-DC converter. Also, a plurality of post voltage regulators are tapped to a secondary winding of the DC-DC converter, in which each post voltage regulator includes a voltage level shifter circuit for allowing gate drivers to impose a small amount of dead time on the control pulse signals for driving the internal transistor switches to minimize the dead time loss occurred during power conversion operation.

Abstract: A reverse current protection circuit is provided to protect the internal circuit components of a switching power supply from being damaged by a reverse current discharging from an input filtering capacitor. The reverse current protection circuit according to a preferred embodiment includes a transistor switch coupled between an input terminal and the input filtering capacitor. The reverse current protection circuit also includes a surveillance device for monitoring the change of a voltage polarity across the current-conducting terminals of the transistor switch and generating a driving signal if the voltage polarity across the current-conducting terminals of the transistor switch is changed. The reverse current protection circuit also includes a signal coupler for coupling the driving signal to the control terminal of the transistor switch in order to turn off the transistor switch so as to block the discharging loop of the reverse current.