DC-DC converter with switchable control mode

A DC—DC converter for converting a direct current (DC) input voltage into a plurality of DC output voltages, which converter may be operated in a normal operation mode and an energy-saving mode, wherein said DC—DC converter includes:

• a main circuit stage comprising switching elements (M1, M2) for converting the DC input voltage (Vdc) into a first AC voltage (Vac) at two delivery nodes (K1, K2),
• an auxiliary circuit stage comprising auxiliary switching elements (M3, M4) and an auxiliary inductor (L2) for converting the DC input voltage (Vdc) into a second AC voltage at the two delivery nodes;
• a first resonant circuit for converting the AC voltages at the delivery nodes into a first AC output voltage, which serves to generate a first DC output voltage in a first frequency range, said first DC output voltage being provided at a main output for supplying the main electronics of an appliance;
• a second resonant circuit for converting the AC voltages at the delivery nodes into a second AC output voltage, which serves to generate a second DC output voltage at a second level in a second frequency range, said second DC output voltage being provided at a standby output for supplying the standby electronics of said appliance;
• and
• a control circuit for activating one of the main circuit stage and the auxiliary circuit stage
• wherein when said first DC output voltage is substantially greater in said first frequency range than said second frequency range and said second DC output voltage is substantially the same in said first and second frequency ranges.