TEMPERATURE DETECTION CIRCUIT AND SEMICONDUCTOR DEVICE

• US 20160131535A1
• Filed: 11/06/2015
• Published: 05/12/2016
• Est. Priority Date: 11/11/2014
• Status: Active Grant

• Current Assignee: Ablic Inc. (MinebeaMitsumi Inc.)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: NAKASHIMO, Takao
• Granted Patent: US 10,078,015 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence
• CPC Class Codes: H02H 5/044 using a semiconductor device to sense the temperature

Abstract

Provided is a temperature detection circuit having less manufacturing fluctuations in detection temperature and capable of easily adjusting the manufacturing fluctuations in detection temperature. The temperature detection circuit includes: a constant current circuit configured to output a constant current; a voltage-controlled current circuit, which is controlled by a voltage output from a heat sensitive element and is configured to output a current corresponding to temperature; and a current comparator configured to compare the constant current and the current corresponding to temperature, and output a detection signal indicating that a predetermined temperature is detected. Temperature characteristics of the constant current circuit and temperature characteristics of the voltage-controlled current circuit have a correlation with each other. The temperature detection circuit is configured to detect temperature based on a result of comparing the output current of the constant current circuit and the output current of the voltage-controlled current circuit.

Claims

1. A temperature detection circuit, comprising:

a constant current circuit configured to output a constant current;

a heat sensitive element;

a voltage-controlled current circuit, which is controlled by a voltage output from the heat sensitive element and configured to output a current corresponding to temperature; and

a current comparator configured to compare the constant current and the current corresponding to temperature, and output a detection signal indicating that a predetermined temperature is detected,

wherein temperature characteristics of the constant current circuit and temperature characteristics of the voltage-controlled current circuit have a correlation with each other.

2. A temperature detection circuit according to claim 1,

wherein the constant current circuit comprises an N-channel depletion transistor, and the voltage-controlled current circuit comprises an N-channel depletion transistor, and

wherein the N-channel depletion transistors have the same gate voltage.

3. A temperature detection circuit according to claim 1,

wherein the constant current circuit comprises:

a first N-channel depletion transistor including a drain connected to a power supply terminal, and a source and a gate connected to each other;

a first N-channel transistor including a source connected to a ground terminal, and a drain connected to the source and the gate of the first N-channel depletion transistor;

a first resistor including one end connected to a gate of the first N-channel transistor, and another end connected to the ground terminal; and

a second N-channel depletion transistor including a source connected to the one end of the first resistor, and a gate connected to the drain of the first N-channel transistor,

wherein the voltage-controlled current circuit comprises a third N-channel depletion transistor including a source connected to one end of the heat sensitive element, a gate connected to the gate of the second N-channel depletion transistor, and a drain connected to an output terminal of the temperature detection circuit,

wherein the heat sensitive element comprises;

a second resistor including one end connected to the source of the third N-channel depletion transistor; and

a diode including one end connected to another end of the second resistor, and another end connected to the ground terminal, and

wherein the current comparator comprises;

a current mirror circuit including an input terminal connected to a drain of the second N-channel depletion transistor, and an output terminal connected to the output terminal of the temperature detection circuit; and

the third N-channel depletion transistor.

4. A temperature detection circuit according to claim 3, wherein the first resistor comprises resistance varying means, and is configured to switch a resistance value of the first resistor based on the detection signal of the temperature detection circuit.

5. A temperature detection circuit according to claim 3, wherein the second resistor comprises resistance varying means, and is configured to switch a resistance value of the second resistor based on the detection signal of the temperature detection circuit.

6. A semiconductor device, comprising the temperature detection circuit of claim 1.

7. A semiconductor device according to claim 6, further comprising an overheat protection circuit,

wherein the temperature detection circuit is formed in the overheat protection circuit.