SWITCHING POWER SUPPLY AND ELECTRONIC EQUIPMENT USING THE SAME

摘要

PURPOSE: To provide a switching power supply and electronic equipment using the same, capable of reducing switching loss, by decreasing much the switching frequency at a low load, and preventing increase of a conduction loss by preventing the switching frequency at a nominal load or heavy load from falling more than required. CONSTITUTION: An on-period control circuit 5 and an off-period control circuit 6 are provided. The off-period control circuit 6 functions to reduce switching frequency at a low load. The on-period control circuit 5 functions, instead of the off-period control circuit 6 at a nominal load or heavy load to prevent lowering of the switching frequency more than required due to the off-period control circuit 6.