Overvoltage protection device for the protection of a power transistor having a MOS control terminal
AssigneeSGS-Thomson Microelectronics S.A.
InventorsLeonardo Fragapane, Romeo Letor
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Abstract
A fast operating, electronic overvoltage protection device intended for a power transistor having at least one control terminal of the MOS type is disclosed. The device comprises a Zener diode associated with the power transistor and integrated together therewith in a semiconductor substrate, and a second transistor connected to the power transistor into a Darlington configuration and also connected to the Zener diode. The protection from overvoltages provided by the device is very fast in operation, and can be implemented in integrated form at reduced cost and without introducing parasitic elements.
Claims21
A fast operating, electronic overvoltage protection device intended for a power transistor having at least one control terminal and being of the MOS type, said protection device comprising a first Zener diode having a first terminal connected to a first terminal of the power transistor and integrated together with said power transistor in a semiconductor substrate;
- a second transistor connected to the power transistor in a Darlington configuration and having a control terminal connected to a second terminal of the Zener diode, a first terminal coupled to the first terminal of the zener diode, and a second terminal, and a second diode connected between the second terminal of the second transistor and the control terminal of the power transistor.
A voltage clamp comprising:
- first switch means having a first terminal, a second terminal and a control terminal;
- and
- second switch means having a first terminal coupled to said control terminal of said first switch means through a low voltage diode, a second terminal connected to said second terminal of said first switch means and a control terminal coupled to said first terminal of said second switch means and connected to said second terminal of said second switch means through a high voltage clamping device.
A power transistor device, comprising:
- a first transistor having control, first, and second terminals;
- a second transistor having a control terminal, a first terminal coupled to the first terminal of the first transistor, and a second terminal;
- and
- a first zener diode connected between the second terminal of the second transistor and the control terminal of the first transistor.
Dependencies are inferred from the claim text.