Patent ID: 7310213

Claim:
A semiconductor device, comprising: a power semiconductor element, which has a control terminal and is disposed on a semiconductor substrate; and an overheat protection circuit, which is arranged between the control terminal of said power semiconductor element and a ground terminal, and is disposed on said semiconductor substrate, wherein: said overheat protection circuit comprises: a driving signal input terminal, to which a driving signal for driving said power semiconductor element is supplied; a first resistor connected between said driving signal input terminal and the control terminal of said power semiconductor element; a second resistor, one end of which is connected to said driving signal input terminal; a semiconductor element for temperature sensing, which has a high potential side terminal connected to the other end of said second resistor, and has a low potential side terminal, and changes a voltage across the high potential side terminal and the low potential terminal according to a temperature change of said semiconductor substrate; a third resistor connected between the low potential side terminal of said semiconductor element for temperature sensing and said ground terminal; a semiconductor element for switching, which has a control terminal connected to the low potential side terminal of said semiconductor element for temperature sensing, and has two main terminals connected to the control terminal of said power semiconductor element and said ground terminal, respectively; a semiconductor element for clamp, which has a high potential side terminal connected to the other end of said second resistor, and has a low potential side terminal connected to said ground terminal, and keeps a voltage between the high potential side terminal of said semiconductor element for temperature sensing and said ground terminal at an almost constant voltage; and a current stabilizing circuit, which keeps a current flow amount into the high potential side terminal of said semiconductor element for clamp at an almost constant level, and said current stabilizing circuit comprises: a transistor for current bypass, the drain of which is connected to the high potential side terminal of said semiconductor element for clamp; a fourth resistor connected between a source of said transistor for current bypass and said ground terminal; a fifth resistor connected between said driving signal input terminal and a gate of said transistor for current bypass; and a sixth resistor connected between the gate of said transistor for current bypass and said ground terminal.