Intel 521 Data Sheet - Page 79

Processor Thermal Features

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Thermal Specifications and Design Considerations 5.1.2 Thermal Metrology The maximum and minimum case temperatures (TC) are specified in Table 5-1. These temperature specifications are meant to help ensure proper operation of the processor. Figure 5-3 illustrates where Intel recommends TC thermal measurements temperature measurement methodology, refer to the should Intel® be made. For detailed guidelines Pentium® 4 Processor on 90 nm on Process in the 775-Land Package Thermal Design Guidelines. Figure 5-3. Case Temperature (TC) Measurement Location Measure TC at this point (geometric center of the package) 37.5 mm 5.2 5.2.1 37.5 mm Processor Thermal Features Thermal Monitor The Thermal Monitor feature helps control the processor temperature by activating the TCC when the processor silicon reaches its maximum operating temperature. The TCC reduces processor power consumption as needed by modulating (starting and stopping) the internal processor core clocks. The Thermal Monitor feature must be enabled for the processor to be operating within specifications. The temperature at which Thermal Monitor activates the thermal control circuit is not user configurable and is not software visible. Bus traffic is snooped in the normal manner, and interrupt requests are latched (and serviced during the time that the clocks are on) while the TCC is active. When the Thermal Monitor feature is enabled, and a high temperature situation exists (i.e., TCC is active), the clocks will be modulated by alternately turning the clocks off and on at a duty cycle specific to the processor (typically 30-50%). Clocks often will not be off for more than 3.0 microseconds when the TCC is active. Cycle times are processor speed dependent and will decrease as processor core frequencies increase. A small amount of hysteresis has been included to prevent rapid active/inactive transitions of the TCC when the processor temperature is near its maximum operating temperature. Once the temperature has dropped below the maximum operating temperature, and the hysteresis timer has expired, the TCC goes inactive and clock modulation ceases. Datasheet 79

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Datasheet
79
Thermal Specifications and Design Considerations
5.1.2
Thermal Metrology
The maximum and minimum case temperatures (T
C
) are specified in
Table 5-1
. These temperature
specifications are meant to help ensure proper operation of the processor.
Figure 5-3
illustrates
where Intel recommends T
C
thermal measurements should be made. For detailed guidelines on
temperature measurement methodology, refer to the
Intel
®
Pentium
®
4 Processor on 90 nm
Process in the 775-Land Package Thermal Design Guidelines
.
5.2
Processor Thermal Features
5.2.1
Thermal Monitor
The Thermal Monitor feature helps control the processor temperature by activating the TCC when
the processor silicon reaches its maximum operating temperature. The TCC reduces processor
power consumption as needed by modulating (starting and stopping) the internal processor core
clocks.
The Thermal Monitor feature must be enabled for the processor to be operating
within specifications.
The temperature at which Thermal Monitor activates the thermal control
circuit is not user configurable and is not software visible. Bus traffic is snooped in the normal
manner, and interrupt requests are latched (and serviced during the time that the clocks are on)
while the TCC is active.
When the Thermal Monitor feature is enabled, and a high temperature situation exists (i.e., TCC is
active), the clocks will be modulated by alternately turning the clocks off and on at a duty cycle
specific to the processor (typically 30–50%). Clocks often will not be off for more than
3.0 microseconds when the TCC is active. Cycle times are processor speed dependent and will
decrease as processor core frequencies increase. A small amount of hysteresis has been included to
prevent rapid active/inactive transitions of the TCC when the processor temperature is near its
maximum operating temperature. Once the temperature has dropped below the maximum
operating temperature, and the hysteresis timer has expired, the TCC goes inactive and clock
modulation ceases.
Figure 5-3. Case Temperature (T
C
) Measurement Location
37.5 mm
Measure T
C
at this point
(geometric center of the package)
37.5 mm
37.5 mm
Measure T
C
at this point
(geometric center of the package)
37.5 mm