| 摘要 |
A switching power supply circuit is provided to comprise a resonance-type converter having a synchronous rectifying circuit, thereby obtaining a high power conversion efficiency, consequently circuit size can be reduced thanks to a simple circuit configuration while a low cost can be realized. A synchronous rectifying circuit(Di) having a coil voltage detection method is equipped on the second side of a resonance-type converter. A flux density of an insulated converter transformer(PIT) is set to be less than a certain value by setting coupling coefficients of the insulated converter transformer(PIT) and setting an organic voltage level of a turn 1(T) of the second coils(N2,N2A,N2B). The second rectifying current is in continuous mode under middle load conditions. By a counter electromotive force created in an inductor(Le) inserted into a path in serial, which flows a rectifying current into the second smoothing condenser(Co), a counter current generated in the rectifying current is suppressed while an invalid power is reduced. |
