Intel 4 HT 631 80552PG0802M2M Data Sheet

82

Datasheet

An external signal, PROCHOT# (processor hot), is asserted when the processor die 

temperature has reached its maximum operating temperature. If the Thermal Monitor 

is enabled (note that the Thermal Monitor must be enabled for the processor to be 

operating within specification), the TCC will be active when PROCHOT# is asserted. The 

processor can be configured to generate an interrupt upon the assertion or de-

assertion of PROCHOT#. Refer to the Intel

Developer’s Manuals for specific register and programming details.

The processor 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 when the processor has 

reached its maximum operating temperature or be driven from an external source to 

activate the TCC. The ability to activate the TCC via PROCHOT# can provide a means 

for thermal protection of system components. 

One application is the thermal protection of voltage regulators (VR). System designers 

can create a circuit to monitor the VR temperature and activate the TCC when the 

temperature limit of the VR is reached. By asserting PROCHOT# (pulled-low) and 

activating the TCC, the VR can cool down as a result of reduced processor power 

consumption. Bi-directional PROCHOT# can allow VR thermal designs to target 

maximum sustained current instead of maximum current. Systems should still provide 

proper cooling for the VR, and rely on bi-directional PROCHOT# only as a backup in 

case of system cooling failure. Refer to the Voltage Regulator-Down (VRD) 10.1 Design 

Guide For Desktop and Transportable LGA775 Socket for details on implementing the 

bi-directional PROCHOT# feature.

Regardless of whether or not Thermal Monitor or Thermal Monitor 2 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 

). At this point, the FSB signal THERMTRIP# will go active and stay active as 

described in 

. THERMTRIP# activation is independent of processor activity and 

does not generate any bus cycles.

T

CONTROL

 is a temperature specification based on a temperature reading from the 

thermal diode. The value for T

CONTROL

 will be calibrated in manufacturing and 

configured for each processor. When T

DIODE

 is above T

CONTROL

, T

C

 must be at or below 

T

C-MAX

 as defined by the thermal profile in 

; otherwise, the 

processor temperature can be maintained at T

CONTROL

 (or lower) as measured by the 

thermal diode.

The purpose of this feature is to support acoustic optimization through fan speed 

control. Contact your Intel representative for further details and documentation.

The processor incorporates an on-die PNP transistor whose base emitter junction is 

used as a thermal "diode", with its collector shorted to Ground. A thermal sensor 

located on the system board may monitor the die temperature of the processor for 

thermal management and fan speed control. 

, and 

provide the "diode" parameter and interface specifications. Two different sets of "diode" 

parameters are listed in 

. The Diode Model parameters (

) 

apply to traditional thermal sensors that use the Diode Equation to determine the