Patent ID: 8912779
Filing Date: 2014-12-16
Classification: H02M

Abstract:
1. A power supply system for producing a regulated output signal at an output node in response to an input signal at an input node, comprises: an inductive device, a plurality of switching circuits for providing connection of the inductive device to the input and output nodes and a ground node, the switching circuits including a first switching circuit provided for coupling the input node to a first node of the inductive device, a second switching circuit provided for coupling the first node of the inductive device to the ground node, a third switching circuit provided for coupling a second node of the inductive device to the ground node, and a fourth switching circuit provided for coupling the second node of the inductive device to the output node, and a switch control circuit for driving the switching circuits so as to enable the power supply system to operate in a boost mode to increase the input signal, in a buck mode to decrease the input signal, and in a buck-boost mode when a difference between the input signal and the output signal is within a predetermined range, the switch control circuit including buck-boost latch circuitry for latching a transition between the buck mode and the buck-boost mode, or between the boost mode and the buck-boost mode based on a predetermined condition, wherein the buck-boost latch circuitry is configured to prevent a transition from the buck or boost mode to the buck-boost mode until an on-time of at least one of the switching circuits reaches a preset minimum value, and to prevent a transition from the buck-boost mode to the buck mode until an on-time of the second switching circuit exceeds the preset maximum value.