Intel LF80537GG0252M Datasheet download pdf (Page 108)

Thermal Specifications and Design Considerations

108 Datasheet

5.1 Monitoring Die Temperature

The processor incorporates three methods of monitoring die temperature:

•Thermal Diode

•Intel® Thermal Monitor

• Digital Thermal Sensor

5.1.1 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, these parameters can be used to calculate silicon temperature values.

For older silicon process technologies, 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 processor, however, is built on Intel’s advanced 45-nm processor technology. Due

to this new processor technology, it is no longer possible to model the substrate

transistor as a simple diode. To accurately calculate silicon temperature 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 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

considered 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).

Tabl e 27 and Tab l e 28 provide the diode interface and transistor model specifications.

Table 27. Thermal Diode Interface

Signal Name Pin/Ball Number Signal Description

THERMDA A24 Thermal diode anode

THERMDC A25 Thermal diode cathode

1 2 ... 103 104 105 106 107 108 109 110 111 112 113

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Intel LF80537GG0252M Datasheet Page 108