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The processor incorporates three methods of monitoring die temperature:
• Thermal diode
• Intel® Thermal Monitor
• Digital thermal sensor
Note:
The Intel Thermal Monitor (detailed in
the maximum specified processor junction temperature has been reached.
5.1
Thermal Diode
The processor incorporates an on-die PNP transistor whose base emitter junction is
used as a thermal "diode", with its collector shorted to Ground. The thermal diode can
be read by an off-die analog/digital converter (a thermal sensor) located on the
motherboard or a stand-alone measurement kit. The thermal diode may be used to
monitor the die temperature of the processor for thermal management or
instrumentation purposes but is not a reliable indication that the maximum operating
temperature of the processor has been reached. When using the thermal diode, a
temperature offset value must be read from a processor model specific register (MSR)
and applied. See
diode usage recommendation when the PROCHOT# signal is not asserted.
Note:
The reading of the external thermal sensor (on the motherboard) connected to the
processor thermal diode signals do not reflect the temperature of the hottest location
on the die. This is due to inaccuracies in the external thermal sensor, on-die
temperature gradients between the location of the thermal diode and the hottest
location on the die, and time-based variations in the die temperature measurement.
Time-based variations can occur when the sampling rate of the thermal diode (by the
thermal sensor) is slower than the rate at which the T
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 from the diode Toffset value programmed into the
processor MSR.
Table 17
of diode parameters are listed in
apply to the traditional thermal sensors that use the diode equation to determine the
processor temperature. Transistor model parameters have been added to support
thermal sensors that use the transistor equation method. The transistor model may
provide more accurate temperature measurements when the diode ideality factor is
closer to the maximum or minimum limits. Please contact your external sensor supplier
for their recommendation. The thermal diode is separate from the Intel Thermal
Monitor's thermal sensor and cannot be used to predict the behavior of the Intel
Thermal Monitor.
5.1.1
Thermal Diode Offset
In order to improve the accuracy of the diode-based temperature measurements, a
temperature offset value (specified as Toffset) is programmed in the processor model-
specific register (MSR) which contains thermal diode characterization data. During
manufacturing each processor thermal diode is evaluated for its behavior relative to the
theoretical diode. Using the equation above, the temperature error created by the
difference n
62
Section 5.1.1
for more details. Please see
to
Table 20
provides the diode interface and specifications. Two different sets
and the actual ideality of the particular processor is calculated.
trim
Section
5.2) must be used to determine when
temperature can change.
J
Table 19
and
Table
20. The diode model parameters
Thermal Specifications
Section 5.2
for thermal
Datasheet
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