TEMPERATURE DETECTION DEVICE

• US 20190310140A1
• Filed: 02/22/2019
• Published: 10/10/2019
• Est. Priority Date: 04/06/2018
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: MORI, Takahiro
• Granted Patent: US 11,454,550 B2
• Time in Patent Office: Days
• 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: H03K 17/0828 in composite switches
• CPC Class Codes: H03K 2017/0806 against excessive temperature

Abstract

A temperature detection device includes a temperature detection diode, a comparator, and a forward current correction circuit. The comparator compares a forward voltage of the temperature detection diode with a threshold voltage and outputs a level signal corresponding to a temperature state. The forward current correction circuit includes a current mirror circuit including a first transistor and a second transistor, a third transistor, an operational amplifier and a variable resistor, and corrects a forward current of the temperature detection diode to change the forward voltage.

Claims

1. A temperature detection device comprising:

a temperature detection diode having an anode and a cathode;

a comparator having a positive input terminal and a negative input terminal, the comparator being configured to compare a forward voltage of the temperature detection diode, received at the positive input terminal thereof, with a threshold voltage received at the negative input terminal thereof, to thereby output a level signal corresponding to a temperature state; and

a forward current correction circuit configured to correct a forward current of the temperature detection diode to change the forward voltage, the forward current correction circuit including

a current mirror circuit including a first transistor and a second transistor,

a third transistor,

an operational amplifier having a positive input terminal, a negative input terminal and an output terminal, and

a variable resistor having a first end and a second end, wherein

each of the first, second and third transistors has a first terminal, a second terminal and a third terminal,

the first terminal of the first transistor is connected to a power supply voltage and the first terminal of the second transistor,

the second terminal of the first transistor is connected to the third terminal of the first transistor, the second terminal of the second transistor and the third terminal of the third transistor,

the third terminal of the second transistor is connected to the positive input terminal of the comparator and the anode of the temperature detection diode,

the positive input terminal of the operational amplifier is connected to a reference voltage, the output terminal of the operational amplifier is connected to the second terminal of the third transistor, and the negative input terminal of the operational amplifier is connected to the first terminal of the third transistor and the first end of the variable resistor; and

the second end of the variable resistor is connected to the cathode of the temperature detection diode and a reference potential.

2. The temperature detection device according to claim 1, further comprising a processor that is configured to

decrease a resistance value of the variable resistor to increase the forward current and increase the forward voltage, and

increase the resistance value of the variable resistor to decrease the forward current and decrease the forward voltage.

3. A temperature detection device comprising:

a temperature detection diode having an anode and a cathode;

a comparator having a positive input terminal and a negative input terminal, the comparator being configured to compare a forward voltage of the temperature detection diode, received at the positive input terminal thereof, with a threshold voltage received at the negative input terminal thereof, to thereby output a level signal corresponding to a temperature state; and

a forward current correction circuit configured to correct a forward current of the temperature detection diode to change the forward voltage, the forward current correction circuit including

a current mirror circuit including a first transistor and a second transistor,

a third transistor,

an operational amplifier having a positive input terminal, a negative input terminal and an output terminal,

a first resistance element having a first end and a second end,

a second resistance element having a first end and a second end, and

a variable resistor having a first end and a second end, wherein

the first terminal of the first transistor is connected to a power supply voltage and the first terminal of the second transistor,

the second terminal of the first transistor is connected to the third terminal of the first transistor, the second terminal of the second transistor and the third terminal of the third transistor,

the third terminal of the second transistor is connected to the positive input terminal of the comparator and the anode of the temperature detection diode,

the first end of the second resistance element is connected to a reference voltage, and the second end of the second resistance element is connected to the first end of the variable resistor and the positive input terminal of the operational amplifier,

the second end of the variable resistor is connected to a reference potential,

the output terminal of the operational amplifier is connected to the second terminal of the third transistor,

the negative input terminal of the operational amplifier is connected to the first terminal of the third transistor and the first end of the first resistance element, and

the second end of the first resistance element is connected to the cathode of the temperature detection diode and the reference potential.

4. The temperature detection device according to claim 3, further comprising a processor that is configured to

decrease a resistance value of the variable resistor to decrease the forward current and decrease the forward voltage, and

increase the resistance value of the variable resistor to increase the forward current and increase the forward voltage.

5. A temperature detection device comprising:

a temperature detection element;

a comparator configured to compare a forward voltage of the temperature detection element with a threshold voltage, to thereby output a level signal corresponding to a temperature state; and

a forward current correction circuit configured to correct a forward current of the temperature detection element to change the forward voltage.