X9000 Datasheet, PDF (73/77 Pages) Intel Corporation – Core2 Duo Processor and Core2 Extreme Processor on 45-nm Process

Thermal Specifications
5.1
Thermal Features
Caution:
Note:
The processor requires a thermal solution to maintain temperatures within operating
limits as set forth in Section 5.1.
Operating the processor outside these operating limits may result in permanent
damage to the processor and potentially other components in the system.
The processor incorporates three methods of monitoring die temperature:
• Thermal diode
• Intel Thermal Monitor
• Digital thermal sensor
The Intel Thermal Monitor (detailed in Section 5.1.2) must be used to determine when
the maximum specified processor junction temperature has been reached.
5.1.1
Table 17.
Thermal Diode
Intel’s processors utilize an SMBus thermal sensor to read back the voltage/current
characteristics of a substrate PNP transistor. Since these characteristics are a function
of temperature, in principle one can use these parameters to calculate silicon
temperature values. For older silicon process technologies it was possible to simplify
the voltage/current and temperature relationships by treating the substrate transistor
as though it were a simple diffusion diode. In this case, the assumption is that the beta
of the transistor does not impact the calculated temperature values. The resultant
diode model essentially predicts a quasi linear relationship between the base/emitter
voltage differential of the PNP transistor and the applied temperature (one of the
proportionality constants in this relationship is processor specific, and is known as the
diode ideality factor). Realization of this relationship is accomplished with the SMBus
thermal sensor that is connected to the transistor.
This processor, however, is built on Intel’s advanced 45-nm processor technology. Due
to this new, highly-advanced processor technology, it is no longer possible to model the
substrate transistor as a simple diode. To accurately calculate silicon temperature one
must use a full bi-polar junction transistor-type model. In this model, the voltage/
current and temperature characteristics include an additional process dependant
parameter which is known as the transistor “beta”. System designers should be aware
that the current thermal sensors on Santa Rosa platforms may not be configured to
account for “beta” and should work with their SMB thermal sensor vendors to ensure
they have a part capable of reading the thermal diode in BJT model.
Offset between the thermal diode-based temperature reading and the Intel Thermal
Monitor reading may be characterized using the Intel Thermal Monitor’s Automatic
mode activation of the thermal control circuit. This temperature offset must be taken
into account when using the processor thermal diode to implement power management
events. This offset is different than the diode Toffset value programmed into the
processor model-specific register (MSR).
Table 17 to Table 18 provide the diode interface and transistor model specifications.
Thermal Diode Interface
Signal Name
Pin/Ball Number
THERMDA
A24
THERMDC
B25
Signal Description
Thermal diode anode
Thermal diode cathode
Datasheet
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