A power supply device of a household appliance has a switching converter having a rectifying stage electrically connected with the mains, a bus capacitor electrically connected in parallel with at least one output terminal of the rectifying stage, a first and second resonant tank electrically connected with at least a terminal of the bus capacitor, a first and second switching device respectively having a first and second switching period and are connected respectively with the first and second resonant tank. The power supply device further has a controller for controlling the first and second switching device. The controller operates at least one of a first switching device independently from the operating conditions of a second switching device. The controller operates the second switching device depending on the operating conditions of the first switching device.