Intel 4 620 JM80547PG0722MM Data Sheet

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With a properly designed and characterized thermal solution, it is anticipated that the TCC would 
only be activated for very short periods of time when running the most power intensive 
applications. The processor performance impact due to these brief periods of TCC activation is 
expected to be so minor that it would be immeasurable. An under-designed thermal solution that is 
not able to prevent excessive activation of the TCC in the anticipated ambient environment may 
cause a noticeable performance loss, and in some cases may result in a T

C

 that exceeds the 

specified maximum temperature and may affect the long-term reliability of the processor. In 
addition, a thermal solution that is significantly under-designed may not be capable of cooling the 
processor even when the TCC is active continuously. Refer to the Intel

90 nm Process in the 775-land LGA Package Thermal Design Guidelines for information on 
designing a thermal solution.

The duty cycle for the TCC, when activated by the Thermal Monitor, is factory configured and 
cannot be modified. The Thermal Monitor does not require any additional hardware, software 
drivers, or interrupt handling routines.

Thermal Monitor 2 provides an efficient mechanism for limiting the processor temperature by 
reducing power consumption within the processor. 

When Thermal Monitor 2 is enabled, and a high temperature situation is detected, the enhanced 
Thermal Control Circuit (TCC) will be activated. This enhanced TCC causes the processor to 
adjust its operating frequency (bus multiplier) and input voltage (VID). This combination of 
reduced frequency and VID results in a decrease in processor power consumption.

A processor enabled for Thermal Monitor 2 includes two operating points, each consisting of a 
specific operating frequency and voltage. The first point represents the normal operating conditions 
for the processor. 

The second point consists of both a lower operating frequency and voltage. When the enhanced 
TCC is activated, the processor automatically transitions to the new frequency. This transition 
occurs very rapidly (on the order of 5 us). 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 VID transitions 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 (i.e., 12.5 mV steps). The processor continues to execute instructions 
during the voltage transition. Operation at this lower voltage reduces both the dynamic and leakage 
power consumption of the processor, providing a reduction in power consumption at a minimum 
performance impact.

Once the processor has sufficiently cooled, and a minimum activation time has expired, the 
operating frequency and voltage transition back to the normal system operating point. Transition of 
the VID code will occur first to insure proper operation once the processor reaches its normal 
operating frequency. Refer to 

 for an illustration of this ordering.