A switching buck converter having an input (In) for an input voltage (V S) and an output (Out) for an output voltage to be supplied to a load (Load), the converter including: - an output stage with a first (Cout) and a second lateral branch and an intermediate branch interposed therebetween, wherein said first lateral branch includes an output capacitor (Cout) for charging at said output voltage, said intermediate branch includes an inductor to circulate current in said output capacitor (Cout) and said second lateral branch includes a freewheeling diode to permit current flow from ground towards said inductor, - a first electronic switch coupled to said input (In) and said output stage (D1, L1, Cout), said first electronic switch having a control electrode, - a second electronic switch coupled to said output capacitor (Cout) and the control electrode of said first electronic switch, said second electronic switch having a respective control electrode, and - a current generator to inject a current (I S) into said respective control electrode of said second electronic switch, to render said second electronic switch conductive and produce alternate switching of the converter between: - a) a first operating condition, wherein said first electronic switch, having become conductive due to said second electronic switch becoming conductive, produces a current flow in said inductor and accumulation of charge on said output capacitor (Cout), and - b) a second operating condition, wherein said first electronic switch opens to produce current flow through said freewheeling diode, said inductor and said output capacitor (Cout) while said second electronic switch is open, the converter including a turn-off circuit (Q3, C1, R6, D2) with a derivative network (C1, R6, D2) acting across said first electronic switch, and being characterized in that said derivative network includes the series connection of: - a turn-off capacitor, and - the parallel connection of a resistor and a diode. - an output stage with a first (Cout) and a second lateral branch and an intermediate branch interposed therebetween, wherein said first lateral branch includes an output capacitor (Cout) for charging at said output voltage, said intermediate branch includes an inductor to circulate current in said output capacitor (Cout) and said second lateral branch includes a freewheeling diode to permit current flow from ground towards said inductor, - a first electronic switch coupled to said input (In) and said output stage (D1, L1, Cout), said first electronic switch having a control electrode, - a second electronic switch coupled to said output capacitor (Cout) and the control electrode of said first electronic switch, said second electronic switch having a respective control electrode, and - a current generator to inject a current (I S) into said respective control electrode of said second electronic switch, to render said second electronic switch conductive and produce alternate switching of the converter between: - a) a first operating condition, wherein said first electronic switch, having become conductive due to said second electronic switch becoming conductive, produces a current flow in said inductor and accumulation of charge on said output capacitor (Cout), and - b) a second operating condition, wherein said first electronic switch opens to produce current flow through said freewheeling diode, said inductor and said output capacitor (Cout) while said second electronic switch is open, - a) a first operating condition, wherein said first electronic switch, having become conductive due to said second electronic switch becoming conductive, produces a current flow in said inductor and accumulation of charge on said output capacitor (Cout), and - b) a second operating condition, wherein said first electronic switch opens to produce current flow through said freewheeling diode, said inductor and said output capacitor (Cout) while said second electronic switch is open, - a turn-off capacitor, and - the parallel connection of a resistor and a diode.