IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0062270
(2002-02-01)
|
우선권정보 |
EP-0830066 (2001-02-01) |
발명자
/ 주소 |
- Spampinato, Sergio Tommaso
- Torres, Antonino
|
출원인 / 주소 |
- STMicroelectronics S.r.l.
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
3 인용 특허 :
5 |
초록
▼
A thermal control circuit for an integrated power transistor includes a current generator controlled by a turn on signal, a sensing resistance in series with the power transistor, and a current limiter acting when the voltage drop on the sensing resistance overcomes a certain value. The circuit also
A thermal control circuit for an integrated power transistor includes a current generator controlled by a turn on signal, a sensing resistance in series with the power transistor, and a current limiter acting when the voltage drop on the sensing resistance overcomes a certain value. The circuit also includes a current amplifier coupled to the output node of the controlled current generator for outputting a drive current that is injected onto a control node of the power transistor. A soft thermal shut down circuit is provided having a conduction state which is enhanced as the temperature increases for reducing the drive current. The circuit controls the voltage on the power transistor in a more effective manner because the current amplifier has a variable gain controlled by the state of conduction of the soft thermal shut down circuit.
대표청구항
▼
1. A thermal control circuit for a power transistor, the power transistor having a control node, the thermal control circuit comprising:a current generator controlled by a turn on signal and having an output node producing a bias current;a sensing resistance in series with the power transistor;a cur
1. A thermal control circuit for a power transistor, the power transistor having a control node, the thermal control circuit comprising:a current generator controlled by a turn on signal and having an output node producing a bias current;a sensing resistance in series with the power transistor;a current limiter acting when a voltage drop on the sensing resistance exceeds a threshold;a current amplifier connected to the output node of said current generator for outputting a drive current to the control node of the power transistor; anda soft thermal shut down circuit having a state of conduction being enhanced as a temperature increases for reducing drive current for the power transistor;said current amplifier having a gain varying as a function of the state of conduction of said soft thermal shut down circuit. 2. The thermal control circuit according to claim 1, wherein said current amplifier comprises a multistage amplifier including an output stage having a signal node; and wherein said soft thermal shut down circuit is connected to the signal node of the output stage and drains a current therefrom as a function of its state of conduction. 3. The thermal control circuit according to claim 1, wherein said current amplifier comprises a first current mirror of first conductivity type including emitter degeneration resistances passing current based upon the bias current of said current generator and an output transistor having conduction nodes coupled respectively to said soft thermal shut down circuit and to said current limiter. 4. The thermal control circuit according to claim 3, wherein said current amplifier further comprises an output current mirror connected in cascade with said first current mirror and having a conductivity of opposite type, said current amplifier comprising a plurality of transistors outputting the drive current as a sum of currents therein. 5. The thermal control circuit according to claim 4, wherein said current amplifier further comprises an input current mirror having a second conductivity type and producing a scaled replica of the bias current. 6. The thermal control circuit according to claim 3, wherein said first current mirror has bias current recovery. 7. The thermal control circuit according to claim 5, wherein said output current mirror and said input current mirror comprise respective emitter degeneration resistances. 8. The thermal control circuit according to claim 1, wherein said current amplifier comprises a plurality of bipolar transistors. 9. The thermal control circuit according to claim 1, further comprising a thermal sensor producing a signal for enabling said soft thermal shut down circuit when the temperature is greater than a predetermined temperature and producing a signal for disabling said soft thermal shut down circuit when the temperature is lower than the predetermined temperature. 10. The thermal control circuit according to claim 9, wherein the predetermined temperature is not lower than 150° C. 11. The thermal control circuit according to claim 1, wherein said soft thermal shut down circuit drains a current such as to nullify the gain of said current amplifier at a temperature not greater than 190° C. 12. A thermal control circuit for a power transistor, the power transistor having a control node, the thermal control circuit comprising:a current generator having an output node producing a bias current;a current amplifier connected to the output node of said current generator for outputting a drive current to the control node of the power transistor; anda soft thermal shut down circuit having a state of conduction being enhanced as a temperature increases for reducing drive current for the power transistor;said current amplifier having a gain varying as a function of the state of conduction of said soft thermal shut down circuit. 13. The thermal control circuit according to claim 12, further comprising a sensing resistance in series with the power transistor, a nd a current limiter acting when a voltage drop on the sensing resistance exceeds a threshold. 14. The thermal control circuit according to claim 12, wherein said current amplifier comprises a multistage amplifier including an output stage having a signal node; and wherein said soft thermal shut down circuit is connected to the signal node of the output stage and drains a current therefrom as a function of its state of conduction. 15. The thermal control circuit according to claim 14, wherein said current amplifier comprises a first current mirror of a first conductivity type including emitter degeneration resistances passing current based upon the bias current of said current generator and an output transistor having conduction nodes coupled respectively to said soft thermal shut down circuit and to said current limiter. 16. The thermal control circuit according to claim 15, wherein said current amplifier further comprises an output current mirror connected in cascade with said first current mirror and having a conductivity of opposite type, said current amplifier comprising a plurality of transistors outputting the drive current as a sum of currents therein. 17. The thermal control circuit according to claim 16, wherein said current amplifier further comprises an input current mirror having a second conductivity type and producing a scaled replica of the bias current. 18. The thermal control circuit according to claim 17, wherein said output current mirror and said input current mirror comprise respective emitter degeneration resistances. 19. The thermal control circuit according to claim 12, further comprising a thermal sensor producing a signal for enabling said soft thermal shut down circuit when the temperature is greater than a predetermined temperature and producing a signal for disabling said soft thermal shut down circuit when the temperature is lower than the predetermined temperature. 20. An integrated circuit comprising:a power transistor and a thermal control circuit connected thereto, said power transistor having a control node, said thermal control circuit comprisinga current generator having an output node producing a bias current,a current amplifier connected to the output node of said current generator for outputting a drive current to the control node of the power transistor, anda soft thermal shut down circuit having a state of conduction being enhanced as a temperature increases for reducing drive current for the power transistor,said current amplifier having a gain varying as a function of the state of conduction of said soft thermal shut down circuit. 21. The integrated circuit according to claim 20, further comprising a sensing resistance in series with the power transistor, and a current limiter acting when a voltage drop on the sensing resistance exceeds a threshold. 22. The integrated circuit according to claim 20, wherein said current amplifier comprises a multistage amplifier including an output stage having a signal node; and wherein said soft thermal shut down circuit is connected to the signal node of the output stage and drains a current therefrom as a function of its state of conduction. 23. The integrated circuit according to claim 20, wherein said current amplifier comprises a first current mirror of a first conductivity type including emitter degeneration resistances passing current based upon the bias current of said current generator and an output transistor having conduction nodes coupled respectively to said soft thermal shut down circuit and to said current limiter. 24. The integrated circuit according to claim 23, wherein said current amplifier further comprises an output current mirror connected in cascade with said first current mirror and having a conductivity of opposite type, said current amplifier comprising a plurality of transistors outputting the drive current as a sum of currents therein. 25. The integrated circuit according to claim 24, wherein said current amplifier furth er comprises an input current mirror having the opposite kind of conductivity and producing a scaled replica of the biasing current. 26. The integrated circuit according to claim 25, wherein said output current mirror and said input current mirror comprise respective emitter degeneration resistances. 27. The thermal control circuit according to claim 20, further comprising a thermal sensor producing a signal for enabling said soft thermal shut down circuit when the temperature is greater than a predetermined temperature and producing a signal for disabling said soft thermal shut down circuit when the temperature is lower than the predetermined temperature. 28. A method of operating a thermal control circuit connected to a power transistor and comprising a current generator producing a bias current, a current amplifier connected to the current generator for outputting a drive current to the power transistor, and a soft thermal shut down circuit having a state of conduction being enhanced as a temperature increases for reducing drive current for the power transistor, the method comprising:varying a gain of the current amplifier as a function of the state of conduction of the soft thermal protection circuit. 29. The method according to claim 28, wherein the thermal control circuit further comprises a sensing resistance in series with the power transistor; and further comprising limiting current when a voltage drop on the sensing resistance exceeds a threshold. 30. The method according to claim 28, wherein the current amplifier further comprises an output stage; and wherein varying the gain comprises attenuating a signal level in the output stage of the current amplifier by draining a current through the soft thermal shut down circuit. 31. The method according to claim 28, further comprising keeping disabled the soft thermal shut down circuit as long as a temperature does not exceed a predetermined value.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.