64 CML24BT cpuModule
BDM-610000084 Rev B
Thermal Management
The cpuModule has several thermal features which can be used to monitor and control the board’s temperature
when extreme operating conditions are prevalent.
Thermal Warning
The cpuModule includes a Thermal Warning mechanism which will assert a signal when the processor’s
temperature has reached or exceeded 100 C. At this time, a bit will be set in the reset and event status register
to indicate that this temperature has been entered. Although the LED has turned white and a thermal warning
bit has been set, the CPU will maintain the current power and operating state.
For more information on the reset status register, refer to
Reset and Event Status Register
—page 68.
ACPI-Enforced Thermal Protection
When the maximum thermal junction temperature of the prcoessor is reached, the system is at risk of
malfuctioning, and the cpuModule may become permanently damanged.
For operating system with ACPI support, the system offers two mechanisms to help prevent the processor from
reaching its maximum thermal junction temperature -- the
Critical Trip Point
and the
Passive Trip Point
. Both
of these temperatures may be configured in the BIOS Setup.
Critical Trip Point
The Critial Trip Point controls the temperature at which an ACPI operating system will shut down the system.
Upon entering the Critical Trip state, the operating system will issue a command to the processor, and the
CML24BT will immediately transition to the
S5
(Soft-Off) ACPI power state.
To exit the Critial Trip state (and S5), the CPU temperature must be reduced to a point that the internal thermal
sensors are below the Critical Trip Point. Next, a power cycle or RSM reset (deepest reset) is required. The reset
button may be configured as an RSM reset (default BIOS setting) in the BIOS setup utility.
For more information on the S5 power state, refer to
Advanced Configuration and Power Interface (ACPI)
—page
65.
Passive Trip Point
The Passive Trip Point controls the temperature at which an ACPI operating system will begin to throttle the
processor.
Further Temperature Reduction
The cpuModule’s temperature is directly related to power consumption. Reducing the power consumption of
the cpuModule will have an effect on the cpuModule’s temperature. Suggested methods for reducing the
cpuModule’s power consumption can be found in the
Power Management
section on page 65.
Summary of Contents for CML24BT cpuModules
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