Temperature detection circuit

• US 20080013597A1
• Filed: 09/18/2007
• Published: 01/17/2008
• Est. Priority Date: 09/14/2004
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Inventors: Mikuni, Takeshi, Tamagawa, Akio
• Granted Patent: US 7,540,657 B2
• Time in Patent Office: Days
• US Class Current: 374/178
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence

Abstract

A temperature detection circuit according to the present invention includes a potential generating part and a temperature detection part. The potential generating part generates a potential according to an environmental temperature, and the temperature detection part detects a temperature based on a detection potential generated in the potential generated part. The temperature detection part is a resistive load type inverter circuit that outputs a detection signal when the generated potential reaches a threshold voltage. The potential generating part applies the detection potential to the inverter circuit through a temperature sensor including cascaded diodes and an NchMOSFET. The threshold voltage of the inverter circuit is determined based on the NchMOSFET in the inverter circuit, and the NchMOSFET is a MOSFET having the same characteristic as the NchMOSFET of the potential generating part.

Claims

1. A temperature detection circuit, comprising:

a first circuit connected between a power input and ground, said first circuit having a constant current component connected to the power input, a diode and first transistor connected in series, said diode and said first transistor being adapted to sense a temperature, a node between said constant current component and said diode having a potential corresponding to the temperature, said first transistor having a first terminal connected to said diode, a gate connected directly to said first terminal and a second terminal connected to ground; and

a second circuit connected between the power input and ground, said second circuit having a resistor connected to the power input and second transistor connected in series, said second transistor having a gate that has the potential of said node and a terminal connected to ground, said first and second transistors having essentially the same threshold voltage,

wherein said second circuit provides an output signal when said second transistor is switched by the potential, the output signal indicating that said diode and said first transistor have reached a predetermined temperature.

2. The temperature detection circuit according to claim 1, wherein said diode is part of a series of cascaded diodes.

3. The temperature detection circuit according to claim 1, wherein said first and second transistors are N-channel MOSFETs.

4. A temperature detection circuit, comprising:

a potential generating part generating a potential corresponding to a detection temperature; and

a temperature detection part detecting a temperature based on a generated potential in the potential generating part,

wherein the temperature detection part includes a first transistor, the potential generating part includes a second transistor which has a gate connected to a drain and substantially the same threshold voltage as the first transistor, and a potential generated by the potential generating part includes a gate-source voltage of the second transistor.

5. The temperature detection circuit according to claim 4, wherein the potential generated by the potential generating part is connected to a gate of the first transistor.

6. The temperature detection circuit according to claim 5, wherein the temperature detection part is an inverter circuit.

7. The temperature detection circuit according to claim 4, wherein the first and second transistors are N-channel MOSFETs.