CP307
Thermal Considerations
ID 34424, Rev. 3.0
Page 6 - 3
P R E L I M I N A R Y
6.
Thermal Considerations
The following chapters provide system integrators with the necessary information to satisfy
thermal requirements when implementing CP307 applications.
6.1
Board Internal Thermal Regulation
The thermal management architecture implemented on the CP307 can be described as being
two separate but related functions. The goal of these functions is to protect the processor and
reduce processor power consumption. Enabling the thermal control circuit allows the processor
to maintain a safe operating temperature without the need for special software drivers or inter-
rupt handling routines.
The two thermal protection functions provided by the processor are:
1. Intel® Core™ Duo and Intel® Core™2 Duo Thermal Supervision
This function controls the processor temperature by SpeedStep® or clock modulation via
the internal Digital Thermal Sensor (DTS).
2. Thermtrip:
In the event of a catastrophic cooling failure resulting in extreme overheating, the proces-
sor and/or the 945GM Express GMCH will automatically shut down when the die temper-
ature has reached approximately 125°C. This event is known as “Thermtrip”.
6.1.1
CPU Internal Thermal Supervision
This function can be enabled and disabled in the BIOS, whereby the default value is: enabled.
When the internal thermal control circuit has been enabled and a high temperature situation
occurs, the internal clocks are controlled by SpeedStep®. If this is not sufficient, the clocks are
additionally modulated by alternately turning them off and on with a 50% duty cycle. This re-
sults in the reduction of the processor power consumption and the processor performance de-
pending on the active SpeedStep® and the duty cycle. Cycle times are processor speed
dependent and will decrease linearly as processor core frequencies increase. The thermal con-
trol circuit is automatically deactivated when the temperature goes below the internal thermal
supervision point. The internal temperature sensors are located near to the hottest area of the
processor dies. Each processor is individually calibrated during manufacturing to eliminate any
potential manufacturing variations.
Note ...
The duty cycle and the internal thermal supervision point is factory configured
by Intel and cannot be modified. For all Intel® Core™ Duo and Intel® Core™2
Duo processors the internal thermal supervision point is 100°C.
Note ...
The TH LED on the front panel always shows the status of the internal thermal
supervision regardless of whether it is enabled or disabled in the BIOS.
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