Device for monitoring the temperature of an element

• US 8,672,540 B2
• Filed: 12/21/2009
• Issued: 03/18/2014
• Est. Priority Date: 12/24/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Inventors: Fornara, Pascal, Rivero, Christian
• Primary Examiner(s): Jagan, Mirellys
• Application Number:
  US12/643,537
• Publication Number:
  US 20100158072A1
• Time in Patent Office: 1,548 Days
• Field of Search: 374/163, 374/183, 374/184, 374/178
• US Class Current: 374/178
• CPC Class Codes: G01K 13/00 Thermometers specially adapted for specific purposes
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 2037/008 Micromechanical switches operated thermally
• CPC Class Codes: H01H 37/46 actuated due to expansion or contraction of a solid deflection of a bimetallic element H01H37/52

Abstract

A device for monitoring the temperature surrounding a circuit, including: a charge storage element; a charge evacuation device; and a thermo-mechanical switch connecting the storage element to the evacuation element, the switch being capable of closing without the circuit being electrically powered, when the temperature exceeds a threshold.

Claims

1. A circuit for monitoring the temperature surrounding the circuit, comprising:

a charge storage element;

a charge evacuation element;

a thermo-mechanical switch connecting the storage element to the evacuation element, said switch being capable of closing without the circuit being electrically powered, when the temperature exceeds a threshold, wherein the thermo-mechanical switch is formed of two metal strips having opposite ends separated by a distance adapted to decreasing as the temperature increases and to come down to zero when the temperature exceeds the threshold; and

a device for reading the amount of charge in the storage element.

2. The circuit of claim 1, comprising an interconnect stack in which the metal strips are formed, the ends of the strips being separated by a region filled with air formed in the interconnect stack.

3. The circuit of claim 1, wherein the metal strips are made of copper or aluminum.

4. The circuit of claim 1, wherein the storage element is formed of a dual-gate MOS transistor comprising a control gate and a floating gate, the floating gate being connected to the thermo-mechanical switch.

5. The circuit of claim 1, wherein the charge evacuation element is formed of a contact between the thermo-mechanical switch and a substrate in and on which the circuit is formed.

6. The circuit of claim 1, formed using CMOS technology.

7. An integrated circuit comprising CMOS components implementing the circuit according to claim 1.

8. A temperature monitoring circuit comprising:

a charge storage element;

a thermo-mechanical switch connected to the charge storage element and configured to discharge the charge storage element when the temperature exceeds a temperature threshold; and

a monitoring device configured to read a charge in the charge storage element, the charge being indicative of whether the temperature threshold has been exceeded, wherein the charge storage element comprises a floating gate of a floating gate transistor.

9. A temperature monitoring circuit as defined in claim 8, wherein the floating gate includes a contact for connection of the floating gate to the thermo-mechanical switch.

10. A temperature monitoring circuit as defined in claim 8, further comprising a selection transistor configured to inject charge into the floating gate of the floating gate transistor.

11. A temperature monitoring circuit as defined in claim 8, wherein the thermo-mechanical switch includes conductive elements separated by a gap.

12. A temperature monitoring circuit as defined in claim 8, further comprising a discharge element coupled to the thermo-mechanical switch and configured to discharge the charge storage element when the thermo-mechanical switch is closed.

13. A temperature monitoring circuit as defined in claim 12, wherein the discharge element is connected between the thermo-mechanical switch and a substrate on which the temperature monitoring circuit is formed.

14. A temperature monitoring circuit as defined in claim 8, wherein the thermo-mechanical switch comprises metal strips separated by a gap.

15. A temperature monitoring circuit as defined in claim 14, wherein a dimension of the gap between the metal strips establishes, at least in part, the temperature threshold.

16. A temperature monitoring circuit as defined in claim 14, wherein the metal strips comprise copper or aluminum.