CP605
System Considerations
ID 25095, Rev. 07
© 2004 Kontron Modular Computers GmbH
Page 6 - 3
2509
5.07.UG.VC.041005/14244
8
6.
System Considerations
6.1
Thermal Management
The total power dissipation of the new generation of Intel Pentium 4 processors has been rap-
idly increasing, pushing cooling technology close to its limits. This requires a new technology
to keep the processor’s die temperature within factory specifications. The following chapters
provide system integrators with the necessary information to satisfy thermal requirements
when implementing CP605 applications.
6.1.1
Passive Thermal Regulation
The thermal management architecture implemented on the CP605 can be described as being
three separate but related functions. The goal of all three functions is to protect the processor
and reduce processor power consumption. Enabling the thermal control circuit allows the pro-
cessor to maintain a safe operating temperature without the need for special software drivers
or interrupt handling routines.
The three thermal protection functions provided by the processor are:
1. Pentium 4 internal thermal monitor:
This function controls the processor temperature by modulating the processor core
clocks.
2. External (MAX1617) thermal monitor:
This function controls via the processor Stopclock signal the power consumption. While
asserted, it has the effect of stopping the clock to many internal elements of the proces-
sor.
3. Thermtrip:
In the event of a cooling failure resulting in extreme overheating, the processor will auto-
matically shut down when the die temperature has reached approximately 135 °C. This
event is known as “Thermtrip”.
6.1.1.1
CPU Internal Thermal Supervision
This function can be enabled and disabled in the BIOS, whereby the default value is: disabled.
When the internal thermal control circuit has been enabled and a high temperature situation
occurs, the internal clocks are modulated by alternately turning the clocks off and on with a duty
cycle dependent on the processor type (typically 30-50%). This results in the processor power
dissipation being reduced accordingly. Cycle times are processor speed dependent and will de-
crease linearly as processor core frequencies increase. The thermal control circuit is automat-
ically deactivated when the temperature goes below the internal thermal supervision point. The
internal temperature sensor is located near on the hottest area of the processor die. Each pro-
cessor is individually calibrated during manufacturing to eliminate any potential manufacturing
variations.
Note ...
The duty cycle and the internal thermal supervision point is factory configured
and cannot be modified. For all Mobile Pentium 4-M processor the internal ther-
mal supervision point is 100 °C.
