Semiconductor device comprising an IGBT and a constant voltage circuit having switches and normally-on type MOSFETs connected in parallel
View Patent ↗A semiconductor device includes an IGBT, a constant voltage circuit, and protection Zener diodes. The IGBT makes/breaks a low-voltage current flowing in a primary coil. The constant voltage circuit and the protection Zener diodes are provided between an external gate terminal and an external collector terminal. The constant voltage circuit supplies a constant gate voltage to the IGBT to thereby set a saturation current value of the IGBT to a predetermined limiting current value. The IGBT has the saturation current value in a limiting current value range of the semiconductor device.
1. A semiconductor device comprising:
an IGBT; and
a constant voltage circuit which applies a constant voltage to a gate of the IGBT to limit a saturation current value of the IGBT to a value not larger than a limiting current value; wherein
the constant voltage circuit includes:
a plurality of diodes connected in series to a plurality of depression type MOSFETs, wherein the depression type MOSFETs are connected in parallel to one another; and
a plurality of selection switches, each selection switch being connected to a respective one of the depression type MOSFETs.
2. The semiconductor device defined in claim 1 , wherein at least the IGBT and the constant voltage circuit are formed integrally on one and the same semiconductor substrate.
3. The semiconductor device defined in claim 1 , wherein at least the IGBT and the constant voltage circuit are formed separately on different semiconductor substrates.
4. The semiconductor device defined in claim 1 , wherein the IGBT is formed in a trench gate structure or a planar gate structure.
5. The semiconductor device defined in claim 4 , wherein at least the IGBT and the constant voltage circuit are formed integrally on one and the same semiconductor substrate.
6. The semiconductor device defined in claim 4 , wherein at least the IGBT and the constant voltage circuit are formed separately on different semiconductor substrates.
7. The semiconductor device defined in claim 1 , wherein a resistor is connected to an emitter of the IGBT.
8. The semiconductor device defined in claim 7 , wherein at least the IGBT and the constant voltage circuit are formed integrally on one and the same semiconductor substrate.
9. The semiconductor device defined in claim 7 , wherein at least the IGBT and the constant voltage circuit are formed separately on different semiconductor substrates.
10. The semiconductor device defined in claim 7 , wherein the resistor is formed on an emitter-side surface layer of the IGBT.
11. The semiconductor device defined in claim 7 , wherein the resistor is formed in a diffusion region in a source region of the IGBT.
12. The semiconductor device defined claim 7 , wherein the resistor is formed on a semiconductor substrate where the constant voltage circuit has been formed.
13. The semiconductor device defined in claim 7 , wherein the resistor is formed in wiring containing aluminum as a main component.
14. The semiconductor device defined claim 13 , wherein the resistor is formed on a semiconductor substrate where the constant voltage circuit has been formed.
15. The semiconductor device defined in claim 7 , wherein the IGBT is formed in a trench gate structure or a planar gate structure.
16. The semiconductor device defined in claim 15 , wherein at least the IGBT and the constant voltage circuit are formed integrally on one and the same semiconductor substrate.
17. The semiconductor device defined in claim 15 , wherein at least the IGBT and the constant voltage circuit are formed separately on different semiconductor substrates.