AC82GL40-SLB95 Datasheet, PDF (88/98 Pages) Intel Corporation – Intel® Celeron® Mobile Processor Dual-Core on 45-nm Process

Thermal Specifications and Design Considerations
Table 29.
5.1.3
Note:
If the n_trim value used to calculate the Toffset differs from the n_trim value used to in a
temperature sensing device, the T_error(nf) may not be accurate. If desired, the Toffset
can be adjusted by calculating n_actual and then recalculating the offset using the n_trim as
defined in the temperature sensor manufacturer’s datasheet.
The n_trim used to calculate the Diode Correction Toffset are listed in Table 29.
Thermal Diode n_trim and Diode Correction Toffset
Symbol
Parameter
Value
n_trim
Diode Ideality used to calculate Toffset 1.01
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 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.
There are two automatic modes called Intel Thermal Monitor 1 and Intel Thermal
Monitor 2. These modes are selected by writing values to the MSRs of the processor.
After automatic mode is enabled, the TCC activates only when the internal die
temperature reaches the maximum allowed value for operation.
When Intel Thermal Monitor 1 is enabled and a high temperature situation exists, the
clocks modulates by alternately turning the clocks off and on at a 50% duty cycle.
Cycle times are processor speed dependent and decreases linearly as processor core
frequencies increase. Once the temperature has returned to a non-critical level,
modulation ceases and TCC goes inactive. A small amount of hysteresis has been
included to prevent rapid active/inactive transitions of the TCC when the processor
temperature is near the trip point. The duty cycle is factory configured and cannot be
modified. Also, automatic mode does not require any additional hardware, software
drivers, or interrupt handling routines. Processor performance decreases by the same
amount as the duty cycle when the TCC is active.
Intel Thermal Monitor 1 and Intel Thermal Monitor 2 features are collectively referred
to as Adaptive Thermal Monitoring features. Intel recommends Intel Thermal Monitor 1
and 2 be enabled on the processors.
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