The switched power supply (10) comprises: an input (16) for an AC input current (IPRI) under an input voltage (VPRI); an output (36) for a DC output current (Isec), and successively, from the input to the output, a system of controlled breaker switches (20); a transformer (21) whereof the primary (24) is linked at the output of the system of controlled breaker switches (20); a rectifying circuit (28) connected across the terminals of a secondary circuit (26) of the transformer; and a storage capacitor (32) linked in parallel across the output terminals of the rectifier circuit (28) with interposition of a coil (34), the output (36) being formed across the terminals of the storage capacitor (32). The system of controlled breaker switches (20) is the only circuit between the input (16) and the output (36) to comprise switching members and in that it comprises means (22) for controlling the system of breaker switches (20) so as to control the amplitude of the input current (IPRI) as a function of the input voltage (VPRI) of the output current (Isec) and of the voltage (Vsec) across the terminals of the storage capacitor (32).