User manual

Kontron Compact Computers AG SMX945 Detailed Manual V1.1

8.2. Thermal Monitor and Catastrophic Thermal Protection

Intel

Core™ Duo processors have a thermal monitor feature that helps to control the processor

temperature. The integrated TCC (Thermal Control Circuit) activates if the processor silicon reaches its

maximum operating temperature. The activation temperature that the Intel Thermal Monitor uses to activate

the TCC cannot be configured by the user nor is its software visible. The Thermal Monitor can control the

processor temperature through the use of two different methods defined as TM1 and TM2. The TM1 method

consists of the modulation (starting and stopping) of the processor clocks at a 50% duty cycle. The TM2

method initiates an Enhanced Intel

SpeedStep

transition to the lowest performance state once the

processor silicon reaches the maximum operating temperature.

The maximum operating temperature for Intel

Core™ Duo processors is 100°C. TM2 mode is used for

Intel

Core™ Duo processors. Two modes are supported by the Thermal Monitor to activate the TCC. They

are called Automatic and On-Demand. No additional hardware, software, or handling routines are necessary

when using Automatic Mode.

To ensure that the TCC is active for only short periods of time, thus reducing the impact on processor

performance to a minimum, it is necessary to have a properly designed thermal solution. The Intel

Core™

Duo processor's datasheet can provide you with more information about this subject.

The THERMTRIP# signal is used by the Intel

Core™ Duo processors for catastrophic thermal protection. If

the processor's silicon reaches a temperature of approximately 125°C then the processor signal

THERMTRIP# will go active and the system will automatically shut down to prevent any damage to the

processor as a result of overheating. The THERMTRIP# signal activation is completely independent from

processor activity and therefore does not produce any bus cycles.

In order for THERMTRIP# to be able to automatically switch off the system it is necessary to use an ATX-

style power supply.

8.2.1. Thermal Management

ACPI is responsible for allowing the operating system to play an important part in the system's thermal

management. This results in the operating system having the ability to take control of the operating

environment by implementing cooling decisions according to the demands put on the CPU by the

application.