A control circuit for a power transistor, connected between two supply terminals in series with a load. The control circuit comprises a control logic circuit which produces a signal at two levels with respect to a reference terminal, a level shifter connected between the control circuit and the power transistor, which produces a signal at two levels relative to the node between the power transistor and the load. The level shifter comprises a flip-flop the output of which controls the power transistor, and an electronic switch, for example a MOSFET transistor, connected between the "set" input of the flip-flop and the node and controlled by the "reset" input of the flip-flop in such a way as to be closed when the "reset" input is greater, by a predetermined value, than that of the node. The electronic switch prevents the parasitic current flowing through the set and reset inputs from erroneously switching the power transistor.