Abstract: In accordance with the present invention, the above and other objects and advantages are obtained with a bootstrap circuit for a power MOS transistor in a high side configuration. Such circuit includes a first capacitor chargeable to a first voltage which is a function of the supply voltage of the power transistor. It further includes a second capacitor combined with the first capacitor so as to provide a second voltage which is higher than the first voltage and the threshold voltage of the power transistor.

Abstract: The device for protection against the short circuit of an MOS-type power device comprises at least one secondary branch cirucit arranged in parallel with a main branch circuit which includes the power transistor. The secondary branch includes a control MOS transistor having the same characteristics as the power transistor under control and the ability to conduct a current equal to a fraction of that flowing through the power transistor. The gate of the control transistor is connected directly with that of the power transistor. The secondary branch also includes means sensitive to temperature which, in the case of a current flow corresponding to the short circuit current of the power transistor, act on the gate common to the control and to the power transistors so as to lower its voltage and thus limit the conduction of same.

Abstract: The power device has a power supply terminal, a load terminal connected to earth by means of an inductive load and a control terminal connected to a circuit with inlet for an alternating control signal. Whenever the power device is turned off, a switching element hitches the voltage of the control terminal to that of the load terminal, which is forced to fall by the inductive load. There is provided a discharge circuit of the inductive load, which includes means having a predetermined threshold which are fired when the voltage of the load terminal falls down to said predetermined threshold.