Patent ID: 7176667

Claim:
A buck-boost voltage converter comprising: a switching circuit having an input switching unit for selectively coupling a first terminal of an inductor to an input voltage and a ground potential, and an output switching unit for selectively coupling a second terminal of the inductor to an output voltage and the ground potential; a first pulse generating circuit for generating a first pulse signal with a first duty ratio, which is modulated in response to the output voltage; a second pulse generating circuit for generating a second pulse signal with a second duty ratio, which is a constant larger than zero and smaller than one; and a mode control circuit for operating the switching circuit in: at least one pure mode such that one of the input switching unit and the output switching unit is controlled by the first pulse signal, and another of the input switching unit and the output switching unit is kept at a consistent coupling state, and at least one interfacial mode such that one of the input switching unit and the output switching unit is controlled by the first pulse signal, and another of the input switching unit and the output switching unit is controlled by the second pulse signal.