Patent ID: 8081495

Claim:
An over-power compensation circuit for use in a switched mode power supply for switching a current supplied from an input line through an inductance using a power transistor and having a current sense circuit for sensing a current flowing through the power transistor, comprising: a peak detector having an input for receiving an input voltage derived from the input line, and an output, wherein said peak detector comprises: a counter having an input, and an output; a digital-to-analog converter having a first input, a second input coupled to said output of said counter, and an output; a comparator having a first input coupled to said output of said digital-to-analog converter, a second input for receiving said input voltage derived from the input line, and an output; a delay circuit having an input, and an output coupled to a reset terminal of said counter; and a NAND gate having a first input coupled to an output of an oscillator, a second input coupled to the output of said comparator, and an output coupled to said input of said counter; a sample-and-hold circuit having an input coupled to said output of said peak detector, and an output; a current offset generator having an input coupled to said output of said sample-and-hold circuit, and an output for providing an offset current; and an offset resistor having a first terminal coupled to said output of said current offset generator, and a second terminal adapted to be coupled to a current conducting electrode of the power transistor.