Overcurrent control circuit of power semiconductor device

An overcurrent limiting circuit of a power semiconductor element which has first and second regions for passing a main current, a third region for controlling said main current which flows from said first region towards said second region, a current detecting region for passing a current sense current from said second region, and a first electrode terminal, a second electrode terminal, a third electrode terminal, and a current sense terminal connected to said first region, said second region, said third region, and said current detecting region, respectively, comprising:

• a resistor connected between said second electrode terminal and said current sense terminal;
• a transistor comprising a first main electrode, a second main electrode, and a main control electrode connected to said third electrode terminal, said second electrode terminal, and said current sense terminal, respectively, which comes into an ON state to pass a current from said first main electrode towards said second main electrode when a voltage not lower than a first control voltage is applied to said main control electrode;
• and
• voltage clamping means connected between said main control electrode and said second main electrode of said transistor, for clamping a voltage applied to said main control electrode to a second control voltage not lower than said first control voltage when a voltage which is a product of said current sense current and a value of said resistor becomes a predetermined value not lower than said first control voltage.

A semiconductor device, comprising:

• a power semiconductor element having first and second regions for passing a main current, a third region for controlling said main current which flows from said first region towards said second region, a current detecting region for passing a current sense current from said second region, and a first electrode terminal, a second electrode terminal, a third electrode terminal, and a current sense terminal connected to said first region, said second region, said third region, and said current detecting region, respectively;
• a resistor connected between said second electrode terminal and said current sense terminal;
• a transistor comprising a first main electrode, a second main electrode, and a main control electrode connected to said third electrode terminal, said second electrode terminal, and said current sense terminal, respectively, which comes into an ON state to pass a current from said first main electrode towards said second main electrode when a voltage not lower than a first control voltage is applied to said main control electrode;
• and
• a voltage clamping circuit connected between said main control electrode and said second main electrode of said transistor, for clamping a voltage applied to said main control electrode to a second control voltage not lower than said first control voltage when a voltage which is a product of said current sense current and a value of said resistor becomes a predetermined value not lower than said first control voltage.

An overcurrent limiting circuit of a power semiconductor element which has first and second regions for passing a main current, a third region for controlling said main current which flows from said first region towards said second region, a current detecting region for passing a current sense current from said second region, and a first electrode terminal, a second electrode terminal, a third electrode terminal, and a current sense terminal connected to said first region, said second region, said third region, and said current detecting region, respectively, comprising:

• a resistor connected between said second electrode terminal and said current sense terminal;
• a first transistor comprising a first main electrode, a second main electrode, and a main control electrode connected to said third electrode terminal, said second electrode terminal, and said current sense terminal, respectively, which comes into an ON state to pass a current from said first main electrode towards said second main electrode when a voltage not lower than a first control voltage is applied to said main control electrode;
• and
• a voltage clamping circuit connected between said main control electrode and said second main electrode of said first transistor, for clamping a voltage applied to said main control electrode to a second control voltage not lower than said first control voltage when a voltage which is a product of said current sense current and a value of said resistor becomes a predetermined value not lower than said first control voltage,
• said voltage clamping circuit comprises:
• a second transistor having a first electrode, a second electrode, and a control electrode connected to said main control electrode and said second main electrode of said transistor and said other end of said first resistor, respectively, which comes into an ON state to pass a current from said first electrode towards said second electrode when said voltage which is the product of said current sense current and the value of said resistor becomes said predetermined value,
• a voltage between said first electrode and said second electrode of the second transistor in the ON state is set not lower than said first control voltage, and
• said second control voltage is defined based on said voltage between said first electrode and said second electrode.