Miscellaneous active electrical nonlinear devices – circuits – and – External effect – Temperature
Utility Patent
1999-04-13
2001-01-02
Wells, Kenneth B. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
External effect
Temperature
C327S307000, C327S512000, C374S172000
Utility Patent
active
06169442
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an integrated circuit monitoring chip for monitoring the output of a temperature sensing element which measures the temperature of a component in a computer, and the invention also relates to a computer comprising the IC monitoring chip, and to a method for monitoring the temperature of a component in a computer.
BACKGROUND TO THE INVENTION
The operating temperature of a computer is relatively critical. It is important that the ambient temperature within a computer, and in particular, the operating temperature of some of the integrated circuit chips should remain within predetermined upper and lower temperature limits. In particular, it is important that the temperature of the integrated circuit chips and other components should not exceed upper predetermined temperature limits. Temperature sensors for monitoring the temperature within a computer, and also for monitoring the temperature of integrated circuit chips are know. Typically, such sensors comprise a temperature sensing element such as a thermal diode or a substrate transistor which typically are formed in the chip. The output of such sensing elements is relayed to analysing means, which typically is implemented in software in the central processing unit, which compares the monitored temperature with the respective upper and lower temperatures limits. On the monitored temperature falling outside the upper or lower limits, corrective action is taken, for example, by switching on a cooling fan, slowing down the operating speed of the computer or other suitable corrective action.
However, there are two problems with such temperature sensors. Firstly, in general, it is not possible to measure the temperature at the precise location of the component, the temperature of which is to be monitored, and thus a temperature difference generally exists between the component and the site at which the temperature is measured. In general, a temperature sensing element such as a thermal diode or a substrate transistor is formed in the substrate of the chip for sensing the temperature. However, generally, the temperature sensing element must be located some distance from the site of the component the temperature of which is to be monitored. For example, in a central processing unit (CPU) chip the location at which the temperature may be critical is at the heat sink thermal plate. However, since the temperature sensing element is provided by a substrate thermal diode or transistor which is located in the substrate, the temperature being sensed by the temperature sensing element is not the true temperature of the thermal plate, and the actual temperature of the thermal plate could be higher or lower than the temperature being sensed by the sensing element.
Secondly, the monitoring of temperature requires processing time in order to read and analyse the temperature sensed by the temperature sensing element and to compare the analysed temperature with upper and lower predetermined limits. This processing time is required at regular predetermined intervals at which the temperature is to be checked. This is a particular problem in the case of CPU chips, since the monitoring and analysis of the temperature and comparing the temperature with upper and lower predetermined limits is carried out by the CPU under the control of a software sub-routine. For example, in the case of the INTEL XEON (Trade Mark) processor a temperature sensing element is formed in the substrate of the processor for monitoring the temperature of the thermal plate of the processor. Accordingly, a running programme in the INTEL XEON (Trade Mark) processor must be interrupted at regular predetermined intervals to allow the sub-routine to monitor, analyse and compare the temperature sensed by the temperature sensing element. This, slows down the running programme, and thus leads to inefficiency in the processor. Additionally, storage space is required to store the sub-routine for reading, analysing and comparing the temperature. Furthermore, should a CPU fail to read and analyse the temperature sensed by the temperature sensing element due to a lock-up condition occurring in the CPU or due to the CPU being busy and failing to interrupt at a time when the temperature should be read and analysed, an over temperature or an under temperature condition could go undetected with potentially serious consequences.
Various solutions have been proposed to overcome the problem of the temperature difference between the temperature sensing element and the site at which it is desired to monitor the temperature. For example, one solution which has been implemented in the INTEL XEON (Trade Mark) processor is to store a thermal reference byte in the form of an eight bit word on board the processor. The thermal reference byte is an absolute value of temperature which corresponds to the temperature which would be sensed by the temperature sensing element should the temperature of the thermal plate reach an upper predetermined limit value, which should not be exceeded by the thermal plate. In other words, the absolute value of temperature stored as the thermal reference byte is different to the upper predetermined temperature limit value of the thermal plate by the amount of the temperature difference between the thermal plate and the temperature sensing element. The temperature sensed by the temperature sensing element is thus compared with the thermal reference byte, and on the sensed temperature exceeding that of the thermal reference byte appropriate corrective action is taken.
However, this solution does not overcome the problem of the processing time required to regularly analyse the temperature sensed by the temperature sensing element, nor does it address the problem of a lock-up condition occurring in the CPU, and while it does to some extent compensate for the temperature difference between the temperature sensing element and the thermal plate, it does not entirely overcome this problem either. For example, the thermal reference bytes are written into the processor during manufacture, and take no account of how the processor is subsequently configured. The temperature of the thermal plate, in general, is a function of how the processor is configured in the computer, and thus, depending on the configuration of the computer the temperature difference between the temperature sensing element and the thermal plate can vary relatively significantly from computer to computer. Accordingly, the analysing sub-routine may determine an over temperature condition of the thermal plate when no such over temperature condition exists, and more seriously the analysing sub-routine may fail to determine an over temperature condition of the thermal plate until it is too late.
There is therefore a need for a method and an IC monitoring chip which overcomes these problems.
The present invention is directed towards providing such a method and an IC monitoring chip.
SUMMARY OF INVENTION
According to the invention there is provided an integrated circuit monitoring chip for monitoring the output of a temperature sensing element, the IC chip comprising:
an on-chip first input means for receiving a first input signal from the temperature sensing element corresponding to a temperature value sensed by the temperature sensing element,
an on-chip temperature offset storing means for storing a temperature offset value,
an on-chip adding means for adding the stored temperature offset value and the temperature value of the first input signal,
an on-chip output means for outputting an output signal from the IC chip in response to the output from the adding means, and
an on-chip second input means being provided to the temperature offset storing means for facilitating writing the temperature offset value to the temperature offset storing means.
In one embodiment of the invention the temperature offset storing means comprises a temperature offset register in the chip for storing the temperature offset value in digital form.
Preferably, the adding means adds the absolut
Blake John
Meehan Patrick
Thomson David
Analog Devices Inc.
Wells Kenneth B.
Wolf Greenfield & Sacks P.C.
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