Temperature monitoring circuit

• US 8,514,089 B2
• Filed: 01/25/2011
• Issued: 08/20/2013
• Est. Priority Date: 12/28/2010
• Status: Expired due to Fees

• Current Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Inventors: Huang, Yong-Zhao
• Primary Examiner(s): Mehmood, Jennifer
• Assistant Examiner(s): ALAM, MIRZA F
• Application Number:
  US13/012,825
• Publication Number:
  US 20120161972A1
• Time in Patent Office: 938 Days
• Field of Search: 340/584, 340/511, 340/514, 340/577, 340/587, 340/628, 340/630, 340/500, 340/505, 340/506, 340/825.21, 340/825.54, 324/720, 324/105, 324/721, 361/103, 361/106, 361/100, 361/93.8, 307/116, 307/117, 307/127, 307/126
• US Class Current: 340/584
• CPC Class Codes: G01K 7/16 using resistive elements resistive elements per se H01C, H01L

Abstract

A temperature monitoring circuit includes a negative temperature coefficient (NTC) resistor, a zener diode, an alarm, a silicon controlled rectifier. A first terminal of the NTC resistor is connected to a power supply through a first resistor. A second terminal of the NTC resistor is grounded. A cathode of the zener diode is connected to a node between the NTC resistor and the first resistor. An anode is grounded through a second resistor. A first terminal of the alarm is connected to the cathode of the zener diode, and is grounded through a third and fourth resistors in series. A cathode of the silicon controlled rectifier is connected to the anode of the zener diode. An anode of the silicon controlled rectifier is connected to a second terminal of the alarm. A control terminal of the silicon controlled rectifier is connected to a node between the third and fourth resistors.

Claims

1. A temperature monitoring circuit comprising:

a negative temperature coefficient (NTC) resistor, wherein a first terminal of the NTC resistor is connected to a power supply through a first resistor, a second terminal of the NTC is grounded;

a zener diode, wherein a cathode of the zener diode is connected to a node between the NTC resistor and the first resistor, an anode of the zener diode is grounded through a second resistor;

an alarm, wherein a first terminal of the alarm is connected to the cathode of the zener diode, and is grounded through a third resistor and a fourth resistor connected in series; and

a silicon controlled rectifier, wherein a cathode of the silicon controlled rectifier is connected to the anode of the zener diode, an anode of the silicon controlled rectifier is connected to a second terminal of the alarm, a control terminal of the silicon controlled rectifier is connected to a node between the third resistor and the fourth resistor.

2. The temperature monitoring circuit of claim 1, wherein the alarm is a light-emitting diode, an anode of the light-emitting diode is the first terminal of the alarm, a cathode of the light-emitting diode is the second terminal of the alarm.

3. The temperature monitoring circuit of claim 1, wherein the alarm is a buzzer, a first terminal of the buzzer is the first terminal of the alarm, a second terminal of the buzzer is the second terminal of the alarm.

4. A temperature monitoring circuit comprising:

a negative temperature coefficient (NTC) resistor, wherein a first terminal of the NTC resistor is connected to a power supply through a first resistor, a second terminal of the NTC resistor is grounded;

a zener diode, wherein a cathode of the zener diode is connected to a node between the NTC resistor and the first resistor, an anode of the zener diode is grounded through a second resistor;

a fan, wherein a first terminal of the fan is grounded through a third resistor and a fourth resistor connected in series; and

a silicon controlled rectifier, wherein a cathode of the silicon controlled rectifier is connected to the anode of the zener diode, an anode of the silicon controlled rectifier is connected to a second terminal of the fan, a control terminal of the silicon controlled rectifier is connected to a node between the third resistor and the fourth resistor.

5. The temperature monitoring circuit of claim 4, further comprising an alarm connected to the fan in parallel.

6. The temperature monitoring circuit of claim 5, wherein the alarm is a light-emitting diode, an anode of the light-emitting diode is connected to the first terminal of the fan, a cathode of the light-emitting diode is connected to the second terminal of the fan.

7. The temperature monitoring circuit of claim 5, wherein the alarm is a buzzer.