an integrated circuit including a power stage , a low - voltage component separated from the power stage by an isolating region and a reference potential region at a reference potential . the power stage includes an n - type substrate region which may be biased to a terminal voltage with respect to the reference potential and the isolating region has p - type conductivity . the low - voltage component includes an n - type input region receiving an input voltage . the input voltage and the terminal voltage may oscillate a few tens of volts above or below the reference potential and turn on parasitic transistors . to prevent turning on of the parasitic transistors , switchable conductive paths are interposed between the isolating region on the one hand , and the substrate region , the input region and the reference potential region on the other , for electrically connecting the isolating region to one of the substrate region , input region and reference potential region which presents instant by instant the lowest potential .