Dual-constant-time buck-boost switching regulator and control circuit and method thereof

摘要

The present invention provides a dual constant time buck-boost switching regulator, and a control circuit and a method thereof. The buck-boost switching regulator converts an input voltage to an output voltage and it includes a buck circuit and a boost circuit. The buck circuit includes an inductor, a buck power switch and a buck power device. The boost circuit includes the inductor, a boost power switch and a boost power device. The present invention controls the buck power switch to be OFF by a constant OFF time in the buck conversion mode, and controls the boost power switch to be ON by a constant ON time in the boost conversion mode. An offset signal ensures that the buck-boost regulator operates only in pure buck conversion mode and pure boost conversion mode, but does not need to operate in a buck-boost conversion mode.