Semiconductor device including a surge protecting circuit
A protecting apparatus includes a back-flow preventing Zener diode having a cathode connected directly to a control terminal of a main transistor formed on a semiconductor substrate. A protecting transistor has an output terminal connected to an anode of the back-flow preventing Zener diode and an input terminal connected to an input terminal of the main transistor. A protecting capacitor or Zener diode circuit is connected between a control terminal of the protecting transistor and the input terminal of the main transistor for allowing initial surge current, when caused based on a rapid surge, to flow into the control terminal of the protecting transistor. The protecting transistor, when turning on in response to the initial surge current, allows next surge current succeeding the initial surge current to flow into the control terminal of the main transistor via the back-flow preventing Zener diode. And, the main transistor, when turning on in response to the next surge current, allows late surge current succeeding the next surge current to flow therethrough.
1. A semiconductor device comprising:
an insulated gate transistor disposed in a current path of an electric load;
a gate voltage boosting element having one end connected to a gate electrode of said insulated gate transistor so as to operate in response to a surge applied from a high-voltage terminal of said insulated gate transistor;
a wiring member serving as a parasitic inductance against the applied surge, said wiring member being connected in parallel with said gate voltage boosting element with respect to the high-voltage terminal of said insulated gate transistor,
wherein said insulated gate transistor and said gate voltage boosting element are formed in a chip, and said wiring member is provided outside said chip.
2. The semiconductor device in accordance with claim 1 , wherein said wiring member is a bonding wire.
3. The semiconductor device in accordance with claim 1 , wherein
said chip is a resin molded chip mounted on a printed circuit board, and
said wiring member is a combination of a bonding wire, a lead frame, and a conductive pattern formed on said printed circuit board.
4. The semiconductor device in accordance with claim 1 , wherein
said chip is mounted on a semiconductor substrate by using the flip chip bonding method, and
said wiring member is a conductive pattern formed on said semiconductor substrate.
5. The semiconductor device in accordance with claim 1 , wherein said gate voltage boosting element is a Zener diode.
6. The semiconductor device in accordance with claim 1 , wherein said gate voltage boosting element is a combination of a plurality of circuit elements selected from the group consisting of a Zener diode, a bipolar transistor, and a metal oxide semiconductor transistor.
7. The semiconductor device in accordance with claim 1 , wherein said gate voltage boosting element is a combination of a plurality of circuit elements selected from the group consisting of a capacitor, a bipolar transistor, and a metal oxide semiconductor transistor.
8. The semiconductor device in accordance with claim 1 , wherein said gate voltage boosting element is a set of a capacitor and a Zener diode.
9. The semiconductor device in accordance with claim 1 , wherein said gate voltage boosting element includes a series of a metal oxide semiconductor transistor and a back-flow preventing Zener diode connected between said high-voltage terminal and said gate electrode of said insulated gate transistor, and a capacitor connected between said high-voltage terminal of said insulated gate transistor and a gate electrode of said metal oxide semiconductor transistor.