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Thermal Specifications
to reach the target operating voltage. Each step will be one VID table entry (see
Table
2-3). The processor continues to execute instructions during the voltage
transition. Operation at the lower voltage reduces the power consumption of the
processor.
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 operating frequency and
voltage transition back to the normal system operating point. Transition of the VID
code will occur first, in order to ensure proper operation once the processor reaches its
normal operating frequency. Refer to
Figure 6-6.
Thermal Monitor 2 Frequency and Voltage Ordering
T
T
f
f
MAX
MAX
f
f
V
V
NOM
NOM
V
V
TM2
TM2
The PROCHOT# signal is asserted when a high temperature situation is detected,
regardless of whether Thermal Monitor or Thermal Monitor 2 is enabled.
6.2.4
On-Demand Mode
The processor provides an auxiliary mechanism that allows system software to force
the processor to reduce its power consumption. This mechanism is referred to as "On-
Demand" mode and is distinct from the Thermal Monitor and Thermal Monitor 2
features. On-Demand mode is intended as a means to reduce system level power
consumption. Systems utilizing the Intel
Series must not rely on software usage of this mechanism to limit the processor
temperature. If bit 4 of the IA32_CLOCK_MODULATION MSR is set to a '1', the
processor will immediately reduce its power consumption via modulation (starting and
stopping) of the internal core clock, independent of the processor temperature. When
using On-Demand mode, the duty cycle of the clock modulation is programmable via
bits 3:1 of the same IA32_CLOCK_MODULATION MSR. In On-Demand mode, the duty
cycle can be programmed from 12.5% on/ 87.5% off to 87.5% on/12.5% off in 12.5%
increments. On-Demand mode may be used in conjunction with the Thermal Monitor;
however, if the system tries to enable On-Demand mode at the same time the TCC is
engaged, the factory configured duty cycle of the TCC will override the duty cycle
selected by the On-Demand mode.
Document Number: 318080-002
TM2
TM2
TM2
TM2
Figure 6-6
for an illustration of this ordering.
Temperature
Temperature
Frequency
Frequency
Vcc
Vcc
Time
Time
T(hysterisis)
T(hysterisis)
®
®
Xeon
Processor 7200 Series and 7300
105
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