Apparatus for monitoring ventilation of integrated circuits in electronic apparatus

• US 6,157,897 A
• Filed: 01/30/1998
• Issued: 12/05/2000
• Est. Priority Date: 01/31/1997
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yoshikawa, Minoru
• Primary Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US09/015,910
• Time in Patent Office: 1,040 Days
• Field of Search: 702/130, 702/132, 374/135, 374/137, 361/140, 361/161, 361/164, 361/688, 361/690
• US Class Current: 702/132
• CPC Class Codes: H05K 7/20209 Thermal management, e.g. fan control

Abstract

A temperature IC is mounted to a card mounted within an electronic apparatus for monitoring airflow rate around the card to provide an alarm signal. The temperature IC includes a first IC including a temperature sensor and a second IC disposed downstream of the first IC. The second IC includes a temperature sensor and a resistor as a heating element. The second IC includes a first arithmetic unit that forms the difference in temperature out of two inputs of the temperature sensors, and a second arithmetic unit that determines thermal resistance of the second IC out of the difference in temperature and the quantity of heat released from the resistor. A memory stores date indicative of a relation between values of airflow rate and values of thermal resistance. A third arithmetic unit is provided to refer the stored data using the determined thermal resistance to find airflow rate.

Claims

1. A ventilation monitoring apparatus for protecting integrated circuits within an electronic apparatus against thermal damage, comprising

a temperature integrated circuit (IC) on a card mounted in the electronic apparatus to monitor airflow rate therein for detecting occurrence of an event warranted for producing an alarm, wherein said IC comprises:

a temperature sensor;

a memory for temporarily storing a sensor output of said temperature sensor;

a resistor; and

a switch for establishing and disestablishing an electrical connection between said resistor and a power supply.

8. A ventilation monitoring apparatus as claimed in claim 1, including:

a first arithmetic unit that forms the difference in temperature, measured by said temperature sensor, caused by activation of said switch;

a second arithmetic unit that uses said difference and the quantity of heat released by said resistor to give a thermal resistance;

a memory storing reference data indicative of various values of airflow rate versus various values of thermal resistance of said temperature IC; and

a third arithmetic unit that compares said thermal resistance with said reference data to determine airflow rate.

9. A ventilation monitoring apparatus as claimed in claim 8, wherein said first, second and third arithmetic units include software.

2. A ventilation monitoring apparatus for protecting integrated circuits within an electronic apparatus against thermal damage, comprising:

a first integrated circuit (IC) that includes a temperature sensor; and

a second IC disposed downstream, with respect to flow of ventilation air, of the first IC, said second IC including a temperature sensor and a resistor as a heating element.

3. A ventilation monitoring apparatus as claimed in claim 2, including:

a first arithmetic unit that forms the difference between two inputs from said temperature sensors;

a second arithmetic unit that uses said difference and the quantity of heat released by said resistor to give a thermal resistance;

a memory storing reference data indicative of various values of airflow rate versus various values of thermal resistance; and

a third arithmetic unit that compares said thermal resistance with said reference data to determine airflow rate.

4. A ventilation monitoring apparatus as claimed in claim 3, wherein said second IC includes said first, second and third arithmetic units and said memory.

5. A ventilation monitoring apparatus as claimed in claim 3, wherein said first, second and third arithmetic units include software.

6. A ventilation monitoring apparatus as claimed in claim 3, wherein said reference data includes a readily available calibrated data indicative of relation between thermal resistance and airflow rate.

7. A ventilation monitoring apparatus as claimed in claim 3, wherein said third arithmetic unit is operative to determine whether the input from said temperature of said first IC has reached a preset upper limit for producing an abnormal temperature alarm.

10. A ventilation monitoring apparatus for protecting integrated circuits within an electronic apparatus against thermal damage, comprising:

first and second integrated circuits (ICs), each including a temperature sensor, on a card mounted within the electronic apparatus;

said second IC being disposed downstream, with respect to ventilation air within the electronic apparatus, of said first temperature IC, said second IC including a resistor as a heating element,

said second IC being operative to form the difference between two inputs from said temperature sensors of said first and second ICs,

said second IC being operative to use said difference and the quantity of heat released from said resistor of said second IC to give thermal resistance of said second IC,

said second IC being operative to compare said thermal resistance with a reference data indicative of a predetermined relation between various values of thermal resistance of said second IC and various values of airflow rate to determine airflow rate.

12. A ventilation monitoring apparatus as claimed in claim 10, wherein said second IC is operative to provide an abnormal temperature alarm when the input from said temperature sensor of said first IC has reached a predetermined upper limit.

13. A ventilation monitoring apparatus as claimed in claim 12, wherein said IC is operative to provide an abnormal temperature alarm when the sensor output of said temperature sensor with said switch left turned off has reached a predetermined upper limit.

11. A ventilation monitoring apparatus for protecting integrated circuits within an electronic apparatus against thermal damage, comprising:

an integrated circuit (IC) on a card mounted within the electronic apparatus, said IC including a temperature sensor, a memory storing sensor output of said temperature sensor, a resistor as a heating element and a switch connected to said resistor;

said IC being operative to form the difference between in temperature, measured by sold temperature sensor, caused by activation of said switch,

said IC being operative to use said difference and the quantity of heat released from said resistor to give thermal resistance of said IC,

said IC being operative to compare said thermal resistance with a reference data indicative of a predetermined relation between various values of thermal resistance of said IC and various values of airflow rate to determine airflow rate.

14. A method of monitoring ventilation around integrated circuits within an electronic apparatus, comprising the steps of:

placing a physical body with an internal heating element within an area adjacent an integrated circuit to be protected against thermal damage;

determining thermal resistance of said physical body from the quantity of heat from said heating element and the difference in temperature on said physical body caused by said heating element;

determining data indicative of a relation between values in airflow rate around said physical body and values in thermal resistance of said physical body; and

referring to said determined data using said determined thermal resistance to determine airflow rate around said physical body.

15. A method of monitoring ventilation around integrated circuits within an electronic apparatus, comprising the steps of:

placing a physical body with an internal heating element within an area adjacent an integrated circuit to be protected against thermal damage;

determining thermal resistance of said physical body from the quantity of heat from said heating element and the difference in temperature on said physical body caused by said heating element;

determining date indicative of a relation between values in airflow rate around said physical body and values in thermal resistance of said physical body;

referring to said determined data using said determined thermal resistance to determine airflow rate around said physical body; and

providing an alarm signal when said determined airflow rate drops to a predetermined lower limit.

16. A method of monitoring ventilation around integrated circuits within an electronic apparatus, comprising the steps of:

placing a physical body with an internal heating element within an area adjacent an integrated circuit to be protected against thermal damage;

measuring an inlet temperature of said physical body at a portion upstream of said physical body with respect to airflow within the electronic apparatus;

determining thermal resistance of said physical body from the quantity of heat from said heating element and the difference in temperature on said physical body caused by said heating element;

determining data indicative of a relation between values in airflow rate around said physical body and values in thermal resistance of said physical body;

referring to said determined data using said determined thermal resistance to determine airflow rate around said physical body;

providing a first alarm signal when said determined airflow rate drops to a predetermined lower limit; and

providing a second alarm signal when said measured inlet temperature has reached a predetermined upper limit.