Intel Pentium M 725 RH80536GC0252M Fiche De Données
Codes de produits
RH80536GC0252M
Datasheet
67
Thermal Specifications and Design Considerations
5.1.3
Intel® Thermal Monitor
The Intel Thermal Monitor helps control the processor temperature by activating the
TCC (Thermal Control Circuit) when the processor silicon reaches its maximum
operating temperature. The temperature at which the Intel Thermal Monitor activates
the TCC is not user configurable. Bus traffic is snooped in the normal manner, and
interrupt requests are latched (and serviced during the time that the clocks are on)
while the TCC is active.
With a properly designed and characterized thermal solution, it is anticipated that the
TCC would only be activated for very short periods of time when running the most
power intensive applications. The processor performance impact due to these brief
periods of TCC activation is expected to be minor and hence not detectable. An under-
designed thermal solution that is not able to prevent excessive activation of the TCC in
the anticipated ambient environment may cause a noticeable performance loss, and
may affect the long-term reliability of the processor. In addition, a thermal solution that
is significantly under designed may not be capable of cooling the processor even when
the TCC is active continuously.
The Intel Thermal Monitor controls the processor temperature by modulating (starting
and stopping) the processor core clocks or by initiating an Enhanced Intel SpeedStep
Technology transition when the processor silicon reaches its maximum operating
temperature. The Intel Thermal Monitor uses two modes to activate the TCC:
Automatic mode and on-demand mode. If both modes are activated, Automatic mode
takes precedence.
Note:
The Intel Thermal Monitor automatic mode must be enabled through BIOS for the
processor to be operating within specifications.
There are two automatic modes called Intel Thermal Monitor 1 (TM1) and Intel Thermal
Monitor 2 (TM2). These modes are selected by writing values to the Model Specific
Registers (MSRs) of the processor. After Automatic mode is enabled, the TCC will
activate only when the internal die temperature reaches the maximum allowed value
for operation.
Likewise, when Intel Thermal Monitor 2 is enabled, and a high temperature situation
exists, the processor will perform an Enhanced Intel SpeedStep technology transition to
a lower operating point. When the processor temperature drops below the critical level,
the processor will make an Enhanced Intel SpeedStep technology transition to the last
requested operating point.
TM1 and TM2 can co-exist within the processor. If both TM1 and TM2 bits are enabled in
the auto-throttle MSR, TM2 will take precedence over TM1. However, if TM2 is not
sufficient to cool the processor below the maximum operating temperature then TM1
will also activate to help cool down the processor. Intel recommends Thermal Monitor 1
and Thermal Monitor 2 be enabled on the Intel Pentium Dual-Core processor.
If a processor load based Enhanced Intel SpeedStep technology transition (through
MSR write) is initiated when an Intel Thermal Monitor 2 period is active, there are two
possible results:
1. If the processor load based Enhanced Intel SpeedStep technology transition target
frequency is higher than the Intel Thermal Monitor 2 transition based target
frequency, the processor load-based transition will be deferred until the Intel
Thermal Monitor 2 event has been completed.
2. If the processor load-based Enhanced Intel SpeedStep technology transition target
frequency is lower than the Intel Thermal Monitor 2 transition based target
frequency, the processor will transition to the processor load-based Enhanced Intel
SpeedStep technology target frequency point.