A power switch includes first and second MOS transistors in series between first and second nodes. Both the first and second transistors have a gate coupled to its substrate. First and second resistive elements are coupled between the gate of the first transistor and the first node, and between the gate of the second transistor and the second node, respectively. A triac is coupled between the first and second nodes. The gate of the triac is coupled to a third node common to the first and second transistors. A third MOS transistor has a first conduction electrode coupled to the gate of the first transistor and a second conduction electrode coupled to the gate of the second transistor.