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5.1.4
Digital Thermal Sensor
The Intel
thermometer that can be read via a MSR (no I/O interface). The digital thermometer
shares the thermal sensor of the Intel Thermal Monitor. Intel
GHz/1.83 GHz has a unique digital thermometer whose temperature is accessible via
processor MSR. The digital sensor is the preferred method of reading the processor die
temperature since it can be located much closer to the hottest portions of the die and
can thus more accurately track the die temperature and potential activation of
processor throttling via the Thermal Monitor.
Unlike traditional thermal devices, the Digital Thermometer outputs a temperature
relative to the maximum supported operating temperature of the processor (T
is the responsibility of software to convert the relative temperature to an absolute
temperature. The temperature returned by the Digital Thermometer is always at or
below T
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This bit is also part of the Digital Thermometer 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 guaranteed once the activation of
the Out of Spec status bit is set.
The Digital Thermal Sensor (DTS) relative temperature readout corresponds to the
thermal monitor (TM1/TM2) trigger points. When the DTS indicates maximum
processor core temperature has been reached the TM1 or TM2 hardware thermal
control mechanism activates. The DTS and TM1/TM2 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 guarantee proper operation of the processor within its
temperature operating specifications.
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 TM1 or TM2 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 the Intel Thermal
Monitor 1 (TM1) or Intel Thermal Monitor 2 (TM2) is enabled (note that the TM1 or TM2
must be enabled for the processor to be operating within specification), the TCC is
active when PROCHOT# is asserted. The processor can be configured to generate an
interrupt upon the assertion or deassertion of PROCHOT#. If the processor die cools
down below maximum operating temperature (T
external event, PROCHOT# automatically de-asserts and the processor resumes
normal operation. Refer to the
Manuals
®
®
Intel
Celeron
Processor 1.66 GHz/1.83 GHz
DS
66
®
®
Intel
Celeron
Processor 1.66 GHz/1.83 GHz—Thermal Specifications and Design
®
®
Celeron
Processor 1.66 GHz/1.83 GHz also contains an on die digital
. Over temperature conditions are detectable via an Out Of Spec status bit.
Intel® 64 and IA-32 Architectures Software Developer's
for specific register and programming details.
®
®
Celeron
) either due to TCC activation or an
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Order Number: 315876-002
Considerations
Processor 1.66
). It
J,max
January 2007
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