Patent ID: 8587284

Claim:
A power supply, comprising: an energy transfer element coupled between an input and an output of the power supply; a switch coupled to the energy transfer element to regulate a transfer of energy from the input to the output of the power supply; and a controller coupled to the switch to control switching of the switch, wherein the controller includes: a modulator coupled to a feedback terminal of the controller to receive a feedback signal that is representative of the output of the power supply and to generate an enable signal having first and second logic states in response thereto; a drive signal generator coupled to the modulator and adapted to generate a drive signal to control the switch to regulate the output of the power supply, wherein the drive signal generator enables the switch during a switching period of a clock signal if the enable signal is in the first logic state, and wherein the drive signal generator skips enabling the switch during the switching period if the enable signal is in the second logic state; a comparator coupled to assert an over current signal if a current flowing through the switch exceeds a variable current limit, wherein the drive signal generator disables the switch when the over current signal is asserted; and a variable current limit generator coupled to the comparator to provide the variable current limit, wherein the variable current limit generator sets the variable current limit to a first current limit if the enable signal is in the second logic state during the switching period, and wherein the variable current limit generator sets the variable current limit to a second current limit if the enable signal transitions from the second logic state to the first logic state and the over current signal is asserted during the switching period.