Patent ID: 7616422
Filing Date: 2009-11-10
Classification: H02H

Abstract:
1. An over current protection circuit for a power supply, comprising: an input detection unit receiving a current sensing signal to generate an input voltage; a comparison circuit connecting to the input detection circuit and comparing the input voltage with a reference voltage to generate a compared voltage; a positive feedback sampling and maintaining unit connecting to the input detection unit and the comparison circuit and providing a first and a second feedback current based on the compared voltage, wherein the first feedback current is provided to the input detection unit for further determining the period the over current protection circuit spends operating in normal mode; a timing circuit connecting to the comparison circuit and the positive feedback sampling and maintaining unit and determining the operation cycle of the over current protection circuit; and an output switch connecting to the timing circuit and according to the second feedback current determining whether the over current protection circuit restrains the outputs of the power supply.