Patent ID: 6567280
Filing Date: 2003-05-20
Classification: H02M,Y02B

Abstract:
A method for detecting a light load mode of a switching power supply system, wherein said switching power supply system has a first winding connected to a transformer primary side, a second winding connected to a transformer secondary side, a third winding connected to the transformer primary side having a voltage being in proportion to an output voltage of said second winding, and a signal converting device electrically connected to said third winding in which said third winding is an assistant winding, and an output signal outputted from said assistant winding is processed via said signal converting device and provided for determining whether said switching power supply system is under said light load mode, comprising steps of:measuring a voltage of said signal converting device based on the output signal from said assistant winding; and determining said switching power supply system being under said light load mode when said voltage of said signal converting device is smaller than a predetermined threshold voltage.