Intel
®
Celeron
®
D Processor in the 775-Land LGA Package Thermal Design Guide23
Order #303730
Thermal Management Logic and Thermal Monitor
4.0 Thermal Management Logic and Thermal
Monitor
4.1 Processor Power Dissipation
An increase in processor operating frequency not only increases system performance, but also
increases the processor power dissipation. The relationship between frequency and power is
generalized in the following equation:
P = CV
2
F
Where P = power, C = capacitance, V = voltage, F = frequency.
From this equation, it is evident that power increases linearly with frequency and with the square of
voltage. In the absence of power saving technologies, ever increasing frequencies will result in
processors with power dissipations in the hundreds of watts. Fortunately, there are numerous ways
to reduce the power consumption of a processor, and Intel is aggressively pursuing low power
design techniques. For example, decreasing the operating voltage, reducing unnecessary transistor
activity, and using more power efficient circuits can significantly reduce processor power
consumption.
An on-die thermal management feature called Thermal Monitor is available on the Celeron D
processor in the 775-land LGA package. It provides a thermal management approach to support the
continued increases in processor frequency and performance. By using a highly accurate on-die
temperature sensing circuit and a fast acting Thermal Control Circuit (TCC), the processor can
rapidly initiate thermal management control. The Thermal Monitor can reduce cooling solution
cost, by allowing thermal designs to target TDP.
4.2 Thermal Monitor Implementation
On the Celeron D processor in the 775-land LGA package, the Thermal Monitor is integrated into
the processor silicon. The Thermal Monitor includes:
• A bi-directional signal (PROCHOT#) that indicates if the processor has reached its maximum
temperature or can be asserted externally to activate the Thermal Control Circuit (TCC).
• A TCC that will attempt to reduce processor temperature by rapidly reducing power
consumption when the on-die temperature sensor indicates that it has reached the maximum
operating point.
• Registers to determine the processor thermal status.
4.2.1 PROCHOT# Signal
The Intel Celeron D processor in the 775-Land LGA Package implements a bi-directional
PROCHOT# capability to allow system designs to protect various components from
over-temperature situations. The PROCHOT# signal is bi-directional in that it can either signal
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