Thermal Specifications and Design Considerations
Thermal Monitor feature. The Intel Thermal Monitor can be configured to generate an
interrupt upon the assertion or de-assertion of PROCHOT#.
PROCHOT# will not be asserted when the processor is in the Stop Grant, Sleep, Deep
Sleep, and Deeper Sleep low power states; hence, the thermal diode reading must be
used as a safeguard to maintain the processor junction temperature within maximum
specification. If the platform thermal solution is not able to maintain the processor
junction temperature within the maximum specification, the system must initiate an
orderly shutdown to prevent damage. If the processor enters one of the above low
power states with PROCHOT# already asserted, PROCHOT# will remain asserted until
the processor exits the low power state and the processor junction temperature drops
below the thermal trip point.
If Intel Thermal Monitor automatic mode is disabled, the processor will be operating
out of specification. Regardless of enabling the automatic or on-demand modes, in the
event of a catastrophic cooling failure, the processor will automatically shut down
when the silicon has reached a temperature of approximately 125°C. At this point the
THERMTRIP# signal will go active. THERMTRIP# activation is independent of processor
activity and does not generate any bus cycles. When THERMTRIP# is asserted, the
processor core voltage must be shut down within the time specified in Chapter 3.
5.3
Digital Thermal Sensor
The processor also contains an on-die Digital Thermal Sensor (DTS) that is read via an
MSR (no I/O interface). The DTS is only valid while the processor is in the normal
operating state (the Normal package level low power state).
Unlike traditional thermal devices, the DTS outputs a temperature relative to the
maximum supported operating temperature of the processor (TJ_max). It is the
responsibility of software to convert the relative temperature to an absolute
temperature. The temperature returned by the DTS will always be at or below TJ_max
.
Catastrophic temperature conditions are detectable via an Out Of Spec status bit. This
bit is also part of the DTS MSR. When this bit is set, the processor is operating out of
specification and immediate shutdown of the system should occur. The processor
operation and code execution is not ensured once the activation of the “Out of Spec”
status bit is set.
The DTS-relative temperature readout corresponds to the Intel Thermal Monitor-1 and
Intel Thermal Monitor -2 trigger point. When the DTS indicates maximum processor
core temperature has been reached, the Intel Thermal Monitor-1 or Intel Thermal
Monitor-2 hardware thermal control mechanism will activate. The DTS and Intel
Thermal Monitor-1/Intel Thermal Monitor-2 temperature may not correspond to the
thermal diode reading since the thermal diode is located in a separate portion of the
die and thermal gradient between the individual core DTS. Additionally, the thermal
gradient from DTS to thermal diode can vary substantially due to changes in processor
power, mechanical and thermal attach, and software application. The system designer
is required to use the DTS to ensure proper operation of the processor within its
temperature operating specifications.
Changes to the temperature can be detected via two programmable thresholds located
in the processor MSRs. These thresholds have the capability of generating interrupts
via the core's local APIC.
Datasheet
55
INTEL [ INTEL ]
