# US 5,349,336 A · Overheating detection circuit for detecting overheating of a power device

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- Number: US 5,349,336 A
- Document ID: US5349336A
- Status: Granted
- Kind: A
- Application number: 08/156,700
- Filed: 1993-11-24
- Granted: 1994-09-20
- Earliest claimed: 1990-07-17
- Assignees: Fuji Electric Co., Ltd.
- Inventors: Masaharu Nishiura; Tatsuhiko Fujihira
- Web page: https://patentgrep.com/patent/US5349336A

## CPC

- G01K 3/005: {Circuits arrangements for indicating a predetermined temperature (fire detection G08B17/00)}
- G01K 7/01: using semiconducting elements having PN junctions (G01K7/02, G01K7/16, G01K7/30 take precedence)
- G08B 17/06: Electric actuation of the alarm, e.g. using a thermally-operated switch
- H02H 5/044: {using a semiconductor device to sense the temperature}
- H10D 84/141: {VDMOS having built-in components}
- H10D 84/143: {the built-in components being PN junction diodes}
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

An arrangement for detecting overheating of a power integrated circuit includes a power device integrated in a semiconductor substrate and an overheating detection circuit. The overheating detection circuit includes a reverse biased pn junction formed in the same semiconductor substrate as the power device and having a reverse leakage current flow which is temperature dependent, and a voltage convertor formed in the same semiconductor substrate as the power device and coupled to the pn junction for producing a voltage depending on the reverse leakage current flow. A threshold circuit is connected for receiving the voltage and producing a signal when the voltage exceeds a threshold voltage to indicate that the power device is overheated.

## Claims

### Claim 1

An overheating detection arrangement for detecting overheating of a power integrated circuit, including:
a power device integrated in a semiconductor substrate; and
an overheating detection circuit, including:
a reverse biased pn junction formed in the same semiconductor substrate as said power device and having a reverse leakage current flow which is temperature dependent;
voltage means formed in said semiconductor substrate as said power device and coupled to said pn junction for producing a voltage depending on the reverse leakage current flow; and
threshold means connected for receiving the voltage and producing a signal when the voltage exceeds a threshold voltage to indicate that said power device is overheated;
wherein said semiconductor substrate includes a low impurity concentration layer on one side of said pn junction which has an impurity concentration of not less than 5.times.10.sup.13 /cm.sup.2.

### Claim 2 (depends on 1)

The arrangement as claimed in claim 1, wherein said voltage means comprises a depletion-type MOSFET connected for receiving a constant current.

### Claim 3 (depends on 1)

The arrangement as claimed in claim 1, wherein said voltage means comprises a diffusion resistance layer.

### Claim 4 (depends on 1)

The arrangement as claimed in claim 1, wherein said voltage means comprises a polycrystalline silicon resistance layer.

### Claim 5 (depends on 1)

The arrangement as claimed in claim 1, wherein said voltage means comprises an enhancement-type MOSFET.

### Claim 6

An overheating detection arrangement for detecting overheating of a power integrated circuit, including:
a power device integrated in a semiconductor substrate; and
an overheating detection circuit, including:
a reverse biased pn junction formed in the same semiconductor substrate as said power device and having a reverse leakage current flow which is temperature dependent;
voltage means formed in said semiconductor substrate as said power device and coupled to said pn junction for producing a voltage depending on the reverse leakage current flow; and
threshold means connected for receiving the voltage and producing a signal when the voltage exceeds a threshold voltage to indicate that said power device is overheated;
wherein said voltage means comprises a diffusion resistance layer.

### Claim 7

An overheating detection arrangement for detecting overheating of a power integrated circuit, including:
a power device integrated in a semiconductor substrate; and
an overheating detection circuit, including:
a reverse biased pn junction formed in the same semiconductor substrate as said power device and having a reverse leakage current flow which is temperature dependent;
voltage means formed in said semiconductor substrate as said power device and coupled to said pn junction for producing a voltage depending on the reverse leakage current flow; and
threshold means connected for receiving the voltage and producing a signal when the voltage exceeds a threshold voltage to indicate that said power device is overheated;
wherein said voltage means comprises a polycrystalline silicon resistance layer.

### Claim 8

An overheating detection arrangement for detecting overheating of a power integrated circuit, including:
a power device integrated in a semiconductor substrate; and
an overheating detection circuit comprising:
first and second temperature detecting circuits, said first temperature detecting circuit having a first temperature threshold and said second temperature detecting circuit having a second temperature threshold lower than the first temperature threshold, each of said first and second temperature detecting circuits including:
a reverse biased pn junction formed in the same semiconductor substrate as said power device and having a reverse leakage current flow which is temperature dependent;
voltage means formed in said semiconductor substrate as said power device and coupled to said pn junction for producing a voltage depending on the reverse leakage current flow; and
threshold means connected to said voltage means for receiving the voltage and producing a signal when the voltage exceeds a threshold voltage corresponding to the respective threshold temperature; and
hysteresis means receiving the signals produced by the respective threshold means of said first and second temperature detecting circuits for producing an overheating signal in response to the signal from the threshold means of said first temperature detecting circuit indicating that said power device is overheated and continuing to produce the overheating signal until the signal from the threshold means of said second temperature detecting circuit is discontinued;
wherein said semiconductor substrate includes a low impurity concentration layer on one side of each said pn junction which has an impurity concentration of not less than 5.times.10.sup.13 /cm.sup.2.

### Claim 9 (depends on 8)

The arrangement as claimed in claim 8, wherein each said voltage means comprises a depletion-type MOSFET connected for receiving a constant current.

### Claim 10 (depends on 8)

The arrangement as claimed in claim 8, wherein each said voltage means comprises a diffusion resistance layer.

### Claim 11 (depends on 8)

The arrangement as claimed in claim 8, wherein each said voltage means comprises a polycrystalline silicon resistance layer.

### Claim 12 (depends on 8)

The arrangement as claimed in claim 8, wherein each said voltage means comprises an enhancement-type MOSFET.

### Claim 13

An overheating detection arrangement for detecting overheating of a power integrated circuit, including:
a power device integrated in a semiconductor substrate; and
an overheating detection circuit comprising:
first and second temperature detecting circuits, said first temperature detecting circuit having a first temperature threshold and said second temperature detecting circuit having a second temperature threshold lower than the first temperature threshold, each of said first and second temperature detecting circuits including:
a reverse biased pn junction formed in the same semiconductor substrate as said power device and having a reverse leakage current flow which is temperature dependent;
voltage means formed in said semiconductor substrate as said power device and coupled to said pn junction for producing a voltage depending on the reverse leakage current flow; and
threshold means connected to said voltage means for receiving the voltage and producing a signal when the voltage exceeds a threshold voltage corresponding to the respective threshold temperature; and
hysteresis means receiving the signals produced by the respective threshold means of said first and second temperature detecting circuits for producing an overheating signal in response to the signal from the threshold means of said first temperature detecting circuit indicating that said power device is overheated and continuing to produce the overheating signal until the signal from the threshold means of said second temperature detecting circuit is discontinued;
wherein each said voltage means comprises a diffusion resistance layer.

### Claim 14

An overheating detection arrangement for detecting overheating of a power integrated circuit, including:
a power device integrated in a semiconductor substrate; and
an overheating detection circuit comprising:
first and second temperature detecting circuits, said first temperature detecting circuit having a first temperature threshold and said second temperature detecting circuit having a second temperature threshold lower than the first temperature threshold, each of said first and second temperature detecting circuits including:
a reverse biased pn junction formed in the same semiconductor substrate as said power device and having a reverse leakage current flow which is temperature dependent;
voltage means formed in said semiconductor substrate as said power device and coupled to said pn junction for producing a voltage depending on the reverse leakage current flow; and
threshold means connected to said voltage means for receiving the voltage and producing a signal when the voltage exceeds a threshold voltage corresponding to the respective threshold temperature; and
hysteresis means receiving the signals produced by the respective threshold means of said first and second temperature detecting circuits for producing an overheating signal in response to the signal from the threshold means of said first temperature detecting circuit indicating that said power device is overheated and continuing to produce the overheating signal until the signal from the threshold means of said second temperature detecting circuit is discontinued;
wherein each said voltage means comprises a polycrystalline silicon resistance layer.