Patent ID: 6414404
Filing Date: 2002-07-02
Classification: H03K

Abstract:
A power switching circuit comprising: first and second voltage supply lines; a control signal input terminal; a load terminal for enabling a load to be coupled between the load terminal and the second voltage supply line; a measurement terminal for coupling to a current measurement circuit; a power semiconductor switch having a main current carrying section and a sense current carrying section for carrying a current which is proportional to and smaller than the current carried by the main current carrying section, the main and sense current carrying sections having a control electrode coupled to the control input terminal for controlling switching on and off of the power semiconductor switch and a first main electrode coupled to the first voltage supply line, the main current carrying section having a main current carrying electrode coupled to the load terminal and the sense current carrying section having a sense current carrying main electrode coupled to the measurement terminal, characterized by: at least the main current carrying section comprising a plurality of subsidiary current carrying sections, each subsidiary main current carrying section having a subsidiary main current carrying electrode coupled to the load terminal so that the subsidiary main current carrying electrodes together form the main current carrying electrode and each subsidiary main current carrying section having a respective different control electrode; and by control means for sensing the voltage at the load terminal and for separately controlling with control parameters the supply of a control signal from the control signal input to each of the control electrodes in dependence upon the sensed voltage, said control parameters being selected to cause a drop in resistance in said power switching circuit sufficient to place said circuit into its linear operating range if said circuit exceeds such linear operating range.