THERMISTOR WITH 3 TERMINALS, THERMISTOR-TRANSISTOR, CIRCUIT FOR CONTROLLING HEAT OF POWER TRANSISTOR USING THE THERMISTOR-TRANSISTOR, AND POWER SYSTEM INCLUDING THE CIRCUIT

• US 20100122976A1
• Filed: 10/29/2009
• Published: 05/20/2010
• Est. Priority Date: 11/18/2008
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: KIM, Bongjun, Seo, Giwan, Kim, Hyun Tak
• Granted Patent: US 8,420,987 B2
• Time in Patent Office: Days
• US Class Current: 219/501
• CPC Class Codes: H01C 7/008 Thermistors H01C7/02 - H01C7/06 take precedence
• CPC Class Codes: H01C 7/18 comprising a plurality of layers stacked between terminals
• CPC Class Codes: H01L 27/0248 for electrical or thermal protection, e.g. electrostatic discharge [ESD] protection
• CPC Class Codes: H03K 17/08 Modifications for protecting switching circuit against overcurrent or overvoltage
• CPC Class Codes: H03K 2017/0806 against excessive temperature

Abstract

Provided are a thermistor with 3 terminals, a thermistor-transistor including the thermistor, a circuit for controlling heat of a power transistor using the thermistor-transistor, and a power system including the circuit. The circuit includes: a thermistor-transistor which comprises a thermistor having a resistance decreasing with an increase in temperature and a control transistor connected to the thermistor; and at least one power transistor which is connected to a driving device to control a supply of power to the driving device, wherein the thermistor-transistor is adhered to one of a surface and a heat-emitting part of the at least one power transistor and is connected to one of a base, a gate, a collector, and a drain of the at least one power transistor to decrease or block a current flowing in the at least one power transistor when the temperature of the at least one power transistor rises, so as to prevent the power transistor from heating up.

Claims

1. A thermistor with 3 terminals, wherein the resistance of the thermistor decreases with an increase in temperature, comprising:

a substrate;

a metal heat-emitting electrode which is formed on a lower surface of the substrate to transmit heat;

a thermistor thin-film which is formed on a central portion of an upper surface of the substrate; and

first and second electrodes which are formed on parts of the upper surface of the substrate on both sides of the thermistor thin-film.

2. The thermistor of claim 1, further comprising an insulating buffer layer which is formed between the substrate and the thermistor thin-film.

3. The thermistor of claim 1, further comprising a thermistor protecting insulating layer which is formed on a part of the thermistor thin film and parts of the first and second electrodes in order to protect the thermistor thin film.

4. The thermistor of claim 1, wherein the thermistor thin film has a structure in which one rectangular band is connected between the first and second electrodes or at least two rectangular bands are connected between the first and second electrodes in parallel.

5. The thermistor of claim 1, wherein the thermistor thin film is formed of a semiconductor which comprises one of group III+V semiconductors, group II+V semiconductors, graphene and carbon nano-tubes as a carbon compound, a p-n junction diode, SiGe, ZnO, V₂O₅, p-type GaAs, and p-type Ge.

6. The thermistor of claim 1, wherein the thermistor is packaged in a 3-terminal chip, wherein the metal heat-emitting electrode and the first and second electrodes are respectively connected to the 3 terminals of the chip, which are exposed outside the 3-terminal chip.

7. The thermistor of claim 1, wherein the thermistor is connected to a current driving device in series or in parallel so as to prevent the current driving device from heating up.

8. A thermistor-transistor connected to one of a base, a gate, a collector, and a drain of a power transistor connected to a driving device so as to control a current of the power transistor, comprising:

a thermistor which has a resistance decreasing with an increase in temperature; and

a control transistor which is connected to the thermistor.

9. The thermistor-transistor of claim 8, wherein the thermistor comprises:

a substrate;

a metal heat-emitting electrode which is formed on a lower surface of the substrate to transmit heat;

a thermistor thin-film which is formed on a central portion of an upper surface of the substrate;

first and second electrodes which are formed on parts of the upper surface of the substrate on both sides of the thermistor thin-film.

10. The thermistor-transistor of claim 8, wherein the thermistor is formed using a p-n junction of a junction transistor.

11. The thermistor-transistor of claim 8, wherein the control transistor is one of a NPN-type junction transistor, a PNP-type junction transistor, and a MOS (metal-oxide semiconductor) transistor.

12. The thermistor-transistor of claim 8, wherein the thermistor is connected between a base and a collector of the control transistor.

13. The thermistor-transistor of claim 12, wherein if the thermistor is formed using a p-n junction of a junction transistor, the p-n junction between an emitter and a base of the junction transistor is used as the thermistor, the base of the junction transistor is connected to the emitter of the control transistor, and the emitter of the junction transistor is connected to a base of the control transistor.

14. The thermistor-transistor of claim 8, wherein the driving device is a current driving device and is connected to the thermistor-transistor in series or in parallel.

15. The thermistor-transistor of claim 8, wherein the driving device is one of a high-power LED (light-emitting diode) and a diode.

16. A thermistor-transistor comprising:

a thermistor which is formed using a p-n junction of a junction transistor and has a resistance decreasing with an increase in temperature; and

a control transistor which is connected to the thermistor,

wherein the junction transistor is a power transistor which is connected to a driving device to supply and control a current.

17. A circuit for controlling heat of a power transistor, comprising:

a thermistor-transistor which comprises a thermistor having a resistance decreasing with an increase in temperature and a control transistor connected to the thermistor; and

at least one power transistor which is connected to a driving device to control a supply of power to the driving device,

wherein the thermistor-transistor is adhered to one of a surface and a heat-emitting part of the at least one power transistor and is connected to one of a base, a gate, a collector, and a drain of the at least one power transistor to decrease or block a current flowing in the at least one power transistor when the temperature of the at least one power transistor rises, so as to prevent the at least one power transistor from heating up.

18. The circuit of claim 17, wherein the at least one power transistor comprises one of a NPN-type junction transistor, a PNP-type junction transistor, a MOS transistor, a photodiode (or a photo transistor) using light incident onto a base terminal, a photo relay, a photo SCR (silicon controlled rectifier), an IGBT (insulated-gate bipolar transistor), a SCR, and a triac.

19. The circuit of claim 17, wherein if the at least one power transistor is a junction transistor, the thermistor-transistor is connected between a base and an emitter of the at least one power transistor or between a collector and the emitter of the at least one power transistor, or if the at least one power transistor is a MOS transistor, the thermistor-transistor is connected between a gate and a source of the at least one power transistor or between a drain and the source of the at least one power transistor.

20. The circuit of claim 17, wherein the circuit has a one-chip structure in which the thermistor-transistor, the control transistor, and the at least one power transistor are integrated into one chip.

21. The circuit of claim 20, wherein in the one-chip structure, the thermistor is disposed on the least one power transistor.

22. The circuit of claim 17, wherein the circuit comprises two power transistors which have opposite polarities and are connected to each other through one of a common base and a common gate, wherein the thermistor-transistor is commonly connected between one of the common base and the common gate and output terminals of the two power transistors, a first power transistor of the two power transistors is turned on to supply a current to the driving device, a second power transistor remains off, the thermistor-transistor decreases or blocks the current of the first power transistor when the temperature of the first power transistor rises, and the second power transistor is turned on to allow the current to flow so as to prevent the first power transistor from heating up.

23. The circuit of claim 22, wherein if the temperature of the first power transistor drops or a temperature of the second power transistor rises, the thermistor-transistor turns off the second power transistor and allows a normal current to flow in the first power transistor.

24. The circuit of claim 22, wherein a trigger transistor is connected to a base of the second power transistor.

25. The circuit of claim 22, wherein a combination of the two power transistors is one of a combination of two junction transistors, a combination of two MOS transistors, and a combination of a junction transistor and a MOS transistor.

26. The circuit of claim 17, wherein:

one of a base and a gate of the control transistor is connected to one of the base and the gate of the at least one power transistor through the thermistor, one of an emitter and a source of the control transistor is connected to one of the emitter and the source of the at least one power transistor, and one of a collector and a drain of the control transistor is connected to one of the collector and the drain of the at least one power transistor; and

when the at least one power transistor is turned on to supply the current to the driving device and the temperature of the at least one power transistor rises, the thermistor-transistor decreases or blocks the current of the at least one power transistor and allows a current to flow in the control transistor so as to prevent the at least one power transistor from heating up.

27. The circuit of claim 26, wherein the thermistor comprises at least one of a thermistor with 3 terminals, a MIT (metal-insulator transition) device and a resistor having a resistance varying with temperature.

28. The circuit of claim 26, wherein at least two thermistor-transistors are connected to the at least one power transistor in parallel, and control transistors of the at least two thermistor-transistors are respectively equally connected to the thermistor of the at least two thermistor-transistors and the at least one power transistor.

29. The circuit of claim 17, wherein the thermistor is formed using a p-n junction of a junction transistor, wherein the junction transistor is used as the at least one power transistor.

35. A power system comprising the circuit of claim 17.

36. The power system of claim 35, wherein the power system is one of a power controlling circuit of a cellular phone, a computer, a battery charging circuit, a motor controlling circuit, a power amp, and an electrical and electronic device and a control circuit system of a power supply, an IC (integrated circuit), an LED light bulb, an LED fluorescent lamp, and an LED illumination.

30. A circuit for controlling heat of a power diode, comprising:

the power diode which comprises a first power diode and at least one second power diode connected to the first power diode in parallel; and

a current controlling device which is connected between the first power diode and the at least one second power diode,

wherein a portion of large current flowing in the first power diode flows to the at least one second power diode through the current controlling device so as to control heat of the first power diode.

31. The circuit of claim 30, wherein the current controlling device comprises at least one of a thermistor, a MIT device and a resistor having a resistance varying with temperature.

32. The circuit of claim 30, wherein the circuit is packaged in one chip.

33. The circuit of claim 30, wherein the power diode is a LED, and the circuit is packaged with a light-transmitting lens.

34. The circuit of claim 30, wherein the power diode is a p-n junction diode and comprises one of an LED light bulb and an LED fluorescent lamp.

37. A power system comprising the circuit of claim 30.