Method and apparatus for maintaining a constant load current with line voltage in a switch mode power supply

A switch mode power supply, comprising:

• an energy transfer element coupled between an input of the switch mode power supply and an output of the switch mode power supply;
• a switching device coupled to the energy transfer element to control a delivery of energy from the input of the switch mode power supply to the output of the switch mode power supply;
• a regulator coupled to the switching device, wherein the regulator comprises:
• a comparator coupled to receive a signal representative of a current through the switching device during an on time of the switching device, the comparator further coupled to receive a variable current limit threshold that increases from a first level to a second level during the on time of the switching device;
• a feedback circuit coupled to receive a feedback signal representative of the output of the switch mode power supply;
• and
• a control circuit coupled to the switching device, to an output of the comparator, and to an output of the feedback circuit, the control circuit coupled to control switching of the switching device in response to the output of the comparator and the output of the feedback circuit to regulate the output of the switch mode power supply.