On-Demand Mode; Thermal Monitor 2 Frequency And Voltage Ordering - Intel 5148LV - Xeon Dual Core Active H Datasheet

The second operating point consists of both a lower operating frequency and voltage.
The lowest operating frequency is determined by the lowest supported bus ratio (1/6
for the Dual-Core Intel
processor automatically transitions to the new frequency. This transition occurs rapidly,
on the order of 5 µs. During the frequency transition, the processor is unable to service
any bus requests, and consequently, all bus traffic is blocked. Edge-triggered interrupts
will be latched and kept pending until the processor resumes operation at the new
frequency.
Once the new operating frequency is engaged, the processor will transition to the new
core operating voltage by issuing a new VID code to the voltage regulator. The voltage
regulator must support dynamic VID steps in order to support Thermal Monitor 2.
During the voltage change, it will be necessary to transition through multiple VID codes
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 insure proper operation once the processor reaches its
normal operating frequency. Refer to
Figure 6-6.

Thermal Monitor 2 Frequency and Voltage Ordering

T T
TM2 TM2
f f
MAX MAX
f f
TM2 TM2
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.
6.2.2

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 Dual-Core Intel
must not rely on software usage of this mechanism to limit the processor temperature.
84
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Xeon Processor 5100 Series ). When the TCC is activated, the
Figure 6-6
Temperature Temperature
Frequency Frequency
Vcc Vcc
Time Time
T(hysterisis) T(hysterisis)
Dual-Core Intel
Thermal Specifications
for an illustration of this ordering.
® ®
Xeon Processor 5100 Series
® ®
Xeon Processor 5100 Series Datasheet