RJ80535 Intel, RJ80535 Datasheet - Page 72

• Manufacturer Part Number: RJ80535
• Description: Pentium M Processor
• Manufacturer: Intel

Thermal Specifications and Design Considerations
5.1.2
72
Intel Thermal Monitor
The Intel Thermal Monitor helps control the processor temperature by activating the TCC when the
processor silicon reaches its maximum operating temperature. The temperature at which the Intel
Thermal Monitor activates the thermal control circuit (TCC) is not user configurable and is not
software visible. 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 so minor that it would not be 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
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. The Intel Thermal Monitor
Automatic Mode must be enabled via BIOS for the processor to be operating within
specifications.There are two Automatic modes called Intel Thermal Monitor 1 and Intel Thermal
Monitor 2. 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. Intel Thermal
Monitor 2 is the recommended mode on the Intel Pentium M 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. Intel does not support or recommend operation of the thermal diode under reverse bias. Intel does not
2. Characterized at 100°C.
3. Not 100% tested. Specified by design/characterization.
4. The ideality factor, n, represents the deviation from ideal diode behavior as exemplified by the diode
5. The series resistance, R
support or recommend operation of the thermal diode when the processor power supplies are not within their
specified tolerance range.
equation:
I
Where I
and T = absolute temperature (Kelvin).
temperature. R
board trace resistance between the socket and the external remote diode thermal sensor. R
remote diode thermal sensors with automatic series resistance cancellation to calibrate out this error term.
Another application is that a temperature offset can be manually calculated and programmed into an offset
register in the remote diode thermal sensors as exemplified by the equation:
T
FW
error
=I
1.If the processor load based Enhanced Intel SpeedStep technology transition target
s
= [R
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.
*(e
S
= saturation current, q = electronic charge, V
(qV
T
*(N-1)*I
D
/nkT)
T
as defined, includes the pins of the processor but does not include any socket resistance or
-1)
FWmin
]/[(no/q)*ln N]
T
, is provided to allow for a more accurate measurement of the diode junction
D
= voltage across the diode, k = Boltzmann Constant,
Intel
®
Pentium
®
M Processor Datasheet
®
technology
T
can be used by