Temperature detection circuit

• US 20080198899A1
• Filed: 02/15/2008
• Published: 08/21/2008
• Est. Priority Date: 02/17/2007
• Status: Active Grant

• Current Assignee: Ablic Inc. (MinebeaMitsumi Inc.)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Igarashi, Atsushi
• Granted Patent: US 7,795,950 B2
• Time in Patent Office: Days
• US Class Current: 374/163
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G01K 15/007 Testing
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence
• CPC Class Codes: G01K 7/16 using resistive elements resistive elements per se H01C, H01L

Abstract

Provided is a temperature detection circuit in which an erroneous operation which may be caused at the time of activation of a power supply can be prevented. While an output voltage of a temperature sensor circuit (200) and a reference voltage of a reference voltage circuit (300) are insufficient after the activation of the power supply, an output terminal (700) and a positive power supply terminal (500) are short-circuited with each other by an erroneous operation preventing circuit (100) provided between the output terminal (700) and the positive power supply terminal (500) to prevent the erroneous operation of the temperature detection circuit.

Claims

1. A temperature detection circuit, comprising:

a temperature sensor circuit whose output voltage changes with a temperature;

a reference voltage circuit for generating a reference voltage;

a comparator including an output terminal, for comparing an output voltage from the temperature sensor circuit with the reference voltage to generate a signal inverted based on a predetermined temperature; and

an erroneous operation preventing circuit connected with the output terminal of the comparator,

wherein the erroneous operation preventing circuit sets a predetermined voltage for the output terminal of the comparator immediately after an activation of a power supply.

2. A temperature detection circuit according to claim 1, further comprising a power supply terminal,

wherein the erroneous operation preventing circuit comprises a capacitor connected between the power supply terminal and the output terminal of the comparator.

3. A temperature detection circuit according to claim 1, further comprising a power supply terminal,

wherein the erroneous operation preventing circuit comprises:

a MOS transistor connected between the power supply terminal and the output terminal of the comparator; and

a control circuit connected with a gate of the MOS transistor, for turning off the MOS transistor after a lapse of a predetermined time from the activation of the power supply.

4. A temperature detection circuit according to claim 1, further comprising a power supply terminal,

wherein:

the erroneous operation preventing circuit comprises a MOS transistor connected between the power supply terminal and the output terminal of the comparator; and

the MOS transistor is controlled based on a voltage supplied from an outside to a gate of the MOS transistor.