METHOD AND APPARATUS FOR MAINTAINING CONSTANT LOAD CURRENT WITH LINE VOLTAGE IN SWITCH MODE POWER SUPPLY

摘要

PROBLEM TO BE SOLVED: To provide a power supply including a regulation circuit capable of maintaining approximately constant load current with line voltage. SOLUTION: In one embodiment, a regulation circuit includes a semiconductor switch and current sense circuitry to sense the current in the semiconductor switch. The current sense circuitry has a current limit threshold. The regulation circuit current limit threshold is varied from a first level to a second level during the time when the semiconductor switch is on. One embodiment of the regulation circuit is used in a power supply having an output characteristic having an approximately constant output voltage below an output current threshold and an approximately constant output current below an output voltage threshold. COPYRIGHT: (C)2003,JPO