Patent ID: 6867986
Filing Date: 2005-03-15
Classification: H02M

Abstract:
1. A constant current output control method for a switching power supply circuit having a transformer provided with a primary winding and a secondary output winding; an oscillating switching device connected in-series with the primary winding to connect the primary winding to an energizing direct current power supply; a switching control circuit to execute ON/OFF control of the oscillating switching device; and a rectifying smoothing circuit to rectify and smooth an output of the secondary output winding; the constant current output control method for changing an ON/OFF time of the oscillating switching device of the switching power supply circuit, and executing a constant current output control of an output current I 2o of the rectifying smoothing circuit comprising: deriving an OFF adjustment time T  where, I  controlling an OFF time of the oscillating switching device during the oscillation period T wherein the OFF time is equal to the sum of the output time T setting the output current I