Intel Pentium 4 Processor with 512-KB L2 Cache on 0.13 Micron Process Thermal Design Guidelines

Thermal Specifications

Intel

Pentium

4 Processor Thermal Design Guide 39

3.4.7.2 THERMTRIP#

In the event of a catastrophic cooling failure, the processor will automatically shut down when the

silicon temperature has reached approximately ~135 °C. At this point the system bus signal

THERMTRIP# goes active and power needs to be removed from the processor. THERMTRIP#

stays active until RESET# has been initiated. THERMTRIP# activation is independent of

processor activity and does not generate any bus cycles. Refer to the Intel

Pentium

4 Processor

with 512-KB L2 Cache on 0.13 Micron Process Datasheet for more information about

THERMTRIP#.

3.4.7.3 Thermal Measurement Correlation

There are two independent thermal sensors in the Pentium 4 processor with 512-KB L2 cache on

0.13 micron process. One is the on-die thermal diode described in Section 3.4.7.1. The other is the

temperature sensor used for the Thermal Monitor and for THERMTRIP#. The Thermal Monitor’s

temperature sensor and the on-die thermal diode are independent and isolated devices with no

direct correlation to one another. Circuit constraints and performance requirements prevent the

Thermal Monitor’s temperature sensor and the on-die thermal diode from being located at the

same place on the silicon. As a result, it is not possible to predict the activation of the thermal

control circuit by monitoring the on-die thermal diode.

3.4.8 Cooling System Failure Warning

If desired, the system may be designed to cool the maximum processor power. In this situation, it

may be useful to use the PROCHOT# signal as an indication of cooling system failure. Messages

could be sent to the system administrator to warn of the cooling failure, while the thermal control

circuit would allow the system to continue functioning or allow a graceful system shutdown. If no

thermal management action is taken, the silicon temperature may exceed ~135°C causing

THERMTRIP# to go active and shut down the processor. Regardless of the system design

requirements or cooling solution ability, the Thermal Monitor feature must still be enabled to

guarantee proper processor operation.