Intel Core 2 Quad Q9505 AT80580PJ0736MG User Manual

68

Datasheet

5.

Processor TDP requirements in Intel Dynamic Acceleration mode are lesser than TDP in 
HFM.

6.

At Tj of 100

o

C

7.

At Tj of 50

o

C

8.

At Tj of 35

o

C

The processor incorporates three methods of monitoring die temperature: 

• Thermal  Diode
• Intel® Thermal Monitor
• Digital Thermal Sensor

The Intel Thermal Monitor (detailed in 

) must be used to determine when 

the maximum specified processor junction temperature has been reached.

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 (i.e., Intel® Core™2 Duo 

mobile processors on 65nm process), it is 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.

The quad-core 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).

 provide the diode interface and transistor model specifications.