Patent ID: 7733068
Filing Date: 2010-06-08
Classification: H02M,Y02B

Abstract:
1. A DC-DC converter to control an output voltage, comprising: a switching transistor including a first terminal connected to a power input terminal; an inductor including a first end connected to a second terminal of the switching transistor and a second end connected to an output terminal; a synchronous rectification transistor including a first terminal connected to a junction node between the switching transistor and the inductor and a second terminal connected to a ground terminal; a first electric current detector to detect whether or not an electric current flowing through the synchronous rectification transistor is larger than a first electric current; a second electric current detector to detect whether or not the electric current flowing through the synchronous rectification transistor is larger than a second electric current that is larger than the first electric current and flows in a positive direction; and a selection mechanism to select one of the first electric current detector and the second electric current detector in accordance with a control signal, wherein the synchronous rectification transistor is turned off by an output signal from one of the first electric current detector and the second electric current detector that is selected, and while the synchronous rectification transistor is on, a direction of the electrical current flowing through the synchronous rectification transistor is regarded as the positive direction when the electrical current flows from the junction node to the ground terminal and as a negative direction when the electrical current flows from the ground terminal to the junction node.