Mobile Intel Pentium 4 Processor with 533 MHz Front Side Bus

Mobile Intel
®
Pentium
®
4 Processor with 533 MHz System Bus Datasheet 69
Thermal Specifications and Design Considerations
case of system cooling failure. The system thermal design should allow the power delivery
circuitry to operate within its temperature specification even while the processor is operating at its
TDP. With a properly designed and characterized thermal solution, it is anticipated that
PROCHOT# would only be activated for very short periods of time when running the most power
intensive applications. An under-designed thermal solution that is not able to prevent excessive
assertion of PROCHOT# in the anticipated ambient environment may cause a noticeable
performance loss. Refer to the Intel® 852GM/852PM Chipset Platform Design Guide for details
on implementing the bi-directional PROCHOT# feature.
5.2.4 THERMTRIP# Signal Pin
Regardless of whether or not the Intel Thermal Monitor feature is enabled, in the event of a
catastrophic cooling failure, the processor will automatically shut down when the silicon has
reached an elevated temperature (refer to the THERMTRIP# definition in Table 23). At this point,
the FSB signal THERMTRIP# will go active and stay active as described in Table 23.
THERMTRIP# activation is independent of processor activity and does not generate any bus
cycles. If THERMTRIP# is asserted, processor core voltage (Vcc) must be removed within the
timeframe defined in Table 22.
5.2.5 Thermal Diode
The mobile Intel Pentium 4 processor with 533 MHz FSB incorporates an on-die thermal diode. A
thermal sensor located on the system board may monitor the die temperature of the processor for
thermal management/long term die temperature change purposes. Table 25 and
Table 26 provide the diode parameter and interface specifications. This thermal diode is separate
from the Intel Thermal Monitor’s thermal sensor and cannot be used to predict the behavior of the
Intel Thermal Monitor.
Note: The reading of the thermal sensor connected to the thermal diode does not reflect the temperature
of the hottest location on the die. This is due to inaccuracies in the thermal diode, on-die
temperature gradients between the location of the thermal diode and the hottest location on the die,
and time based variations in the die temperature. Time based variations can occur since the
sampling rate of the sensor is much slower than the die level temperature changes.