The converter uses the energy stored in the output filter of a step-down (or buck) converter and in the inductor of a step up/down (or buck-boost) converter to supply a second output of opposite sign. In particular, the converter has a first input receiving an input voltage; a first output supplying a first output voltage of a first sign; a second output supplying a second output voltage of opposite sign; a controlled switch connected between the first input and a first intermediate node; an inductor connected between the first intermediate node and the first output; a diode connected between the first intermediate node and a second intermediate node; and a dual voltage generating circuit connected between the second intermediate node and the second output.