In order to reduce the cost of a chopping converter supplying a continuous voltage at the terminals of a load (Z), a circuit with three windings (Lp, Ls1, Ls2) and a single magnetic core is proposed, according to the present invention, which enables the cost and the size of the circuit to be reduced. It is then necessary to add two diodes (D3, D4) to the circuit, but these elements are of low cost and of low size.