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Thermal Specifications and Design Considerations
5.1.5
Out of Specification Detection
Overheat detection is performed by monitoring the processor temperature and
temperature gradient. This feature is intended for graceful shut down before the
THERMTRIP# is activated. If the processor's Intel Thermal Monitor 1 or 2 are triggered
and the temperature remains high, an "Out Of Spec" status and sticky bit are latched in
the status MSR register and generates thermal interrupt.
5.1.6
PROCHOT# Signal Pin
An external signal, PROCHOT# (processor hot), is asserted when the processor die
temperature has reached its maximum operating temperature. If Intel Thermal Monitor
1 or 2 is enabled, then the TCC will be active when PROCHOT# is asserted. The
processor can be configured to generate an interrupt upon the assertion or deassertion
of PROCHOT#. Refer to the Intel® 64 and IA-32 Architectures Software Developer's
Manual for specific register and programming details.
The processor implements a bi-directional PROCHOT# capability to allow system
designs to protect various components from overheating situations. The PROCHOT#
signal is bi-directional in that it can either signal when the processor has reached its
maximum operating temperature or be driven from an external source to activate the
TCC. The ability to activate the TCC via PROCHOT# can provide a means for thermal
protection of system components.
Only a single PROCHOT# pin exists at a package level of the processor. When either
core's thermal sensor trips, the PROCHOT# signal will be driven by the processor
package. If only Intel Thermal Monitor 1 is enabled, PROCHOT# will be asserted and
only the core that is above TCC temperature trip point will have its core clocks
modulated. If Intel Thermal Monitor 2 is enabled, then regardless of which core(s) are
above TCC temperature trip point, both cores will enter the lowest programmed Intel
Thermal Monitor 2 performance state. It is important to note that Intel recommends
both Intel Thermal Monitor 1 and 2 to be enabled.
When PROCHOT# is driven by an external agent, if only Intel Thermal Monitor 1 is
enabled on both cores, then both processor cores will have their core clocks modulated.
If Intel Thermal Monitor 2 is enabled on both cores, then both processor cores will
enter the lowest programmed Intel Thermal Monitor 2 performance state. It should be
noted that Force Intel Thermal Monitor 1 on Intel Thermal Monitor 2, enabled via BIOS,
does not have any effect on external PROCHOT#. If PROCHOT# is driven by an external
agent when Intel Thermal Monitor 1, Intel Thermal Monitor 2, and Force Intel Thermal
Monitor 1 on Intel Thermal Monitor 2 are all enabled, then the processor will still apply
only Intel Thermal Monitor 2.
PROCHOT# may be used for thermal protection of voltage regulators (VR). System
designers can create a circuit to monitor the VR temperature and activate the TCC
when the temperature limit of the VR is reached. By asserting PROCHOT# (pulled-low)
and activating the TCC, the VR will cool down as a result of reduced processor power
consumption. Bi-directional PROCHOT# can allow VR thermal designs to target
maximum sustained current instead of maximum current. Systems should still provide
proper cooling for the VR and rely on bi-directional PROCHOT# only as a backup in case
of system cooling failure. The system thermal design should allow the power delivery
circuitry to operate within its temperature specification even while the processor is
operating at its TDP. With a properly designed and characterized thermal solution, it is
anticipated that bi-directional PROCHOT# would only be asserted for very short periods
of time when running the most power intensive applications. An under-designed
thermal solution that is not able to prevent excessive assertion of PROCHOT# in the
anticipated ambient environment may cause a noticeable performance loss.
Datasheet
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