Abstract: A switching power supply circuit uses a magnetic material that is harder to be magnetically saturated than ferrite as a core of a transformer or a choke coil and suitably protects a switching element. The circuit includes a transformer having a core made of a magnetic material of amorphous metal, a primary-side winding and a secondary-side winding. The circuit further includes a switching element for flowing current through the primary-side winding of the transformer according to a pulsive drive signal, and a primary-side current detection circuit for detecting the current flowing through the primary-side winding. The circuit further includes plural circuit elements for rectifying and smoothing a voltage generated in the secondary-side winding of the transformer to generate an output voltage, and a control circuit for generating the drive signal based on at least a detection result of the primary-side current detection circuit, and limiting a period for flowing the current in the primary-side winding.

Abstract: A switching power supply circuit uses a magnetic material that is harder to be magnetically saturated than ferrite as a core of a transformer or a choke coil and suitably protects a switching element. The circuit includes a transformer having a core made of a magnetic material of amorphous metal, a primary-side winding and a secondary-side winding. The circuit further includes a switching element for flowing current through the primary-side winding of the transformer according to a pulsive drive signal, and a primary-side current detection circuit for detecting the current flowing through the primary-side winding. The circuit further includes plural circuit elements for rectifying and smoothing a voltage generated in the secondary-side winding of the transformer to generate an output voltage, and a control circuit for generating the drive signal based on at least a detection result of the primary-side current detection circuit, and limiting a period for flowing the current in the primary-side winding.