Method and apparatus for programmable thermal sensor for an integrated circuit

Abstract

A programmable thermal sensor is implemented in an integrated circuit such as a microprocessor. The programmable thermal sensor monitors the temperature of the integrated circuit, and generates an output to indicate that the temperature of the integrated circuit has attained a pre-programmed threshold temperature. In a microprocessor implementation, the microprocessor contains a processor unit, an internal register, microprogram and clock circuitry. The microprogram writes programmable input values, corresponding to threshold temperatures, to the internal register. The programmable thermal sensor reads the programmable input values, and generates an interrupt when the temperature of the microprocessor reaches the threshold temperature. In addition to a programmable thermal sensor, the microprocessor contains a fail safe thermal sensor that halts operation of the microprocessor when the temperature attains a critical temperature.

What is claimed is:  
     
         1 . A computer, comprising: 
 a clock module, said clock module produces a clock signal having two or more different frequencies;    a processor operatively connected to said clock module, said processor processes instructions in accordance with the clock signal;    a temperature sensor operatively connected to said clock module, said temperature sensor produces a temperature signal based on the temperature of said processor;    a fan;    a fan controller, said fan controller activates the fan in response to the temperature signal,    wherein the frequency of the clock signal supplied to said processor varies depending on the temperature of said processor.    
     
     
         2 . A computer as recited in  claim 1 , wherein the frequency of the clock signal supplied to said processor is reduced as needed to avert overheating of said processor.  
     
     
         3 . A method for producing a clock signal for a microprocessor, said method comprising: 
 (a) providing a fast clock signal;    (b) providing a slow clock signal;    (c) receiving a control signal related to the temperature of the microprocessor; and    (d) selecting between the fast clock signal and slow clock signal in accordance with the control signal,    wherein the control signal is influenced by activity of a fan associated with the microprocessor.    
     
     
         4 . A method as recited in  claim 3 , 
 wherein the fast clock signal is reduced to the slow clock signal by buffering, clock distribution, or phase tuning.    
     
     
         5 . A method for producing a clock for a microprocessor, said method comprising: 
 (a) producing a clock signal having a frequency which varies in accordance with the chip temperature; and    (b) supplying the clock signal to the microprocessor,    wherein the frequency of the clock signal is influenced by activity of a fan associated with the microprocessor which serves as an indicator of the chip temperature.    
     
     
         6 . A method as recited in  claim 5 , wherein said producing (a) comprises: 
 (a1) receiving a high frequency clock; and    (a2) reducing the high frequency clock to a slow frequency clock by buffering, clock distribution, or phase tuning to avert overheating by said processor.    
     
     
         7 . A method for activating speed of a fan that cools a microprocessor, said method comprising the operations of: 
 monitoring temperature of the microprocessor;    producing a control signal based on the temperature of the microprocessor; and    activating the fan in response to the control signal.    
     
     
         8 . A method as recited in  claim 7 , wherein the fan and the microprocessor are parts of a computer.  
     
     
         9 . A computer system, comprising: 
 a processor module, said processor module processes instructions in accordance with a clock signal, and said processor module supports a normal clock mode and a plurality of reduced power modes; and    a temperature sensor thermally coupled to said processor module, said temperature sensor produces a temperature signal based on the temperature of said processor module,    wherein the temperature signal from said temperature sensor is used to regulate the temperature of said processor module by altering the frequency of the clock signal, and    wherein overheating of said processor module is averted by reducing the frequency of the clock signal to a value associated with one of the reduced power modes.    
     
     
         10 . A computer system as recited in  claim 9 , wherein said temperature sensor is internal to said processor module.  
     
     
         11 . A thermal management method for a computer system having a microprocessor, the microprocessor performing operations at a rate determined by a clocking frequency, said thermal management method comprising the acts of: 
 monitoring the temperature of the microprocessor;    comparing the temperature of the microprocessor to first and second temperature thresholds, the second temperature threshold being greater than the first temperature threshold;    reducing the clocking frequency when the temperature of the microprocessor is greater than the first temperature threshold; and    reducing the clocking frequency a second time when the temperature of the microprocessor exceeds the second temperature threshold.    
     
     
         12 . A method as recited in  claim 11 , wherein the clocking frequency is reduced a second time only after the reduction in the clocking frequency does not operate to control thermal conditions of the microprocessor.  
     
     
         13 . A method as recited in  claim 11 , 
 wherein said reducing the clocking frequency is performed by one of buffering, clock distribution, or phase tuning, and    wherein said reducing the clock frequency further reduces the clocking frequency when a prior reduction in the clocking frequency is not able to prevent the temperature of the microprocessor from continuing to increase.    
     
     
         14 . A computer system, comprising: 
 a microprocessor, said microprocessor operating to perform operations in accordance with a clocking frequency;    a fan;    a temperature sensor thermally coupled to said microprocessor, said temperature sensor provides a temperature indication corresponding to the temperature of said microprocessor; and    a thermal manager operatively connected to said microprocessor and said fan, said thermal manager being configured to receive the temperature indication from said temperature sensor, and said thermal manager compares the temperature indication to first and second temperature thresholds, causes the clocking frequency for said microprocessor to be reduced a first time to provide thermal management when the temperature indication indicates that the temperature of said microprocessor exceeds the first temperature threshold, activates said fan when the temperature indication indicates that the temperature of said microprocessor exceeds the first temperature threshold, and causes the clocking frequency to be reduced a second time when the temperature of the microprocessor exceeds the second temperature threshold the second temperature threshold being greater than the first temperature threshold.    
     
     
         15 . A computer system as recited in  claim 14 , wherein said temperature sensor is integrated into said microprocessor.  
     
     
         16 . A computer system as recited in  claim 14 , wherein said second reduction in clock frequency is used only after the first reduction in the clocking frequency for said microprocessor does not operate to sufficiently limit the temperature of said microprocessor.  
     
     
         17 . A computer system as recited in  claim 14 , 
 wherein when the temperature indication indicates that the temperature of said microprocessor does not exceed the second temperature threshold, said second reduction in clock frequency is not implemented.    
     
     
         18 . A computer system as recited in  claim 14 , wherein a plurality of respectively lower clocking frequencies can be used to attempt to stabilize the thermal conditions.  
     
     
         19 . A computer system, comprising: 
 a microprocessor, said microprocessor operates in accordance with a clock signal having a controllable frequency    a fan; and    a thermal management controller operatively connected to said microprocessor and said fan, said thermal management controller operates to thermally manage said microprocessor in accordance with a first cooling mode and a second cooling mode, the first cooling mode involving use of said fan for cooling said microprocessor, and the second cooling mode involving reduction in the controllable frequency of the clock signal for cooling said microprocessor,    wherein, with the first cooling mode, said thermal management controller causes said fan to activate to provide thermal cooling.    
     
     
         20 . A computer system as recited in  claim 19 , wherein, with the second cooling mode, said thermal management controller causes the controllable frequency of the clock to be successively reduced as needed to provided additional cooling.  
     
     
         21 . A computer, comprising: 
 a microprocessor that operates in accordance with a clock, the clock having a controllable frequency;    a temperature sensor that measures a temperature;    a fan; and    a thermal controller for providing thermal management of said computer, said thermal controller has a first cooling mode and a second cooling mode, the controllable frequency of the clock is reduced to regulate thermal conditions when in the first cooling mode, and said fan is activated to regulate thermal conditions when in the second cooling mode,    wherein when said thermal controller operates in the first cooling mode, the controlled frequency of the clock is reduced when the temperature exceeds a first temperature threshold, and    wherein when said thermal controller operates in the second cooling mode, said fan is activated when the temperature exceeds the first temperature threshold.    
     
     
         22 . A computer as recited in  claim 21 , wherein said temperature sensor measures the temperature of said microprocessor.  
     
     
         23 . A computer as recited in  claim 21 , wherein said temperature sensor is integral with said microprocessor.  
     
     
         24 . A computer as recited in  claim 21 , wherein when said thermal controller operates in the first cooling mode, the controllable frequency of the clock is gradually and successively stepwise reduced as needed to regulate thermal conditions.  
     
     
         25 . A computer as recited in  claim 21 , wherein in the first cooling mode cooling of said microprocessor is achieved primarily through reduction in clock frequency for said microprocessor, and wherein in the second cooling mode cooling said microprocessor is achieved primarily through use of said fan.