A device for controlling a transistor, the device comprising an amplifying device (15) for controlling the transistor gate via an output control signal, the device including a first input connected to the transistor drain, the whole assembly forming a first connection, a second input connected to the transistor source, the whole assembly forming a second connection. The control device also comprises: at least one protecting device including at least one switching element (T1) which is inserted in series in the first connection of the amplifying device (15) to prevent a leakage current from passing through the first connection, and a device generating a regulating voltage to control the transistor, the generating device being configured such that there exists the same number of semiconductor junctions between the first and second connections. The invention is in particular applicable on battery charging devices.