Overheating detection circuit for detecting overheating of a power device

• US 5,355,123 A
• Filed: 11/21/1991
• Issued: 10/11/1994
• Est. Priority Date: 07/17/1990
• Status: Expired due to Fees

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Fujihira, Tatsuhiko, Nishiura, Masaharu
• Primary Examiner(s): SWANN III, GLEN R
• Application Number:
  US07/796,266
• Time in Patent Office: 1,055 Days
• Field of Search: 340/653, 340/598, 357/28, 307/310, 361/103, 374/152, 374/178
• US Class Current: 340/653
• CPC Class Codes: G01K 3/005 Circuits arrangements for indicating a predetermined temperature fire detection G08B17/00
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence
• CPC Class Codes: G08B 17/06 Electric actuation of the alarm, e.g. using a thermally-operated switch
• CPC Class Codes: H01L 29/7803 structurally associated with at least one other device assemblies H01L25/00; integrated circuits H01L27/00
• CPC Class Codes: H01L 29/7804 the other device being a pn-junction diode

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 converter 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

1. An overheating detect ion 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.

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

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

4. An overheating detect ion 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 the same 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.

5. The arrangement as claimed in claim 4, wherein each said voltage means comprises a depletion-type MOSFET connected for receiving a constant current.

6. The arrangement as claimed in claim 4, wherein each said voltage means comprises an enhancement-type MOSFET.