Switching converter and control circuit and control method thereof

Abstract

This invention discloses a switching converter and its control circuit and method. The mode switching circuit in the control circuit includes: a first detection module for comparing a loop error signal with a set first reference signal to generate a first enable signal; a second detection module for detecting the system duty cycle and, when the system duty cycle is greater than a set duty cycle, comparing the peak inductor current in the switching converter with a preset peak current to generate a second enable signal; and a switching control module for controlling the switching converter to switch from the normal operating mode to the light-load operating mode when either the first enable signal or the second enable signal is valid. By employing a combination of two detection modes, the light and heavy load conditions of the switching converter can be more accurately determined, thereby avoiding abnormal operation of the switching converter due to misjudgment, ensuring that the system can still enter the light-load operating mode under a large duty cycle, and improving the stability and reliability of the switching converter.

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