Patent ID: 7504805

Claim:
A boost circuit comprising: an inductor wired to an input terminal with a first end of the inductor; a switching device connected between a second end of the inductor and a ground, and configured to be switched in accordance with a control signal input through a control terminal; a rectifying device connected between the second end of the inductor and an output terminal and configured to be switched in accordance with the control signal input through the control terminal, the rectifying device being formed of a MOS transistor; a first transistor wired to the input terminal with a first end of the first transistor and wired to a substrate gate of the rectifying device with a second end of the first transistor, and including a first parasitic diode, the first parasitic diode including a cathode wired to the substrate gate of the rectifying device; a second transistor wired to the substrate gate of the rectifying device with a first end of the second transistor and wired to the output terminal with a second end of the second transistor, and including a second parasitic diode, the second parasitic diode including a cathode wired to the substrate gate of the rectifying device; and a controller configured to control each operation of the switching device, the rectifying device and the first and second transistors so that the first transistor is off and the second transistor is on in a boost mode and the first transistor is on and the second transistor is off in a boost suspend mode.