Intel Core 2 Quad Q8200 BX80570Q8200 User Manual

84

Datasheet

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

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#. 

PROCHOT# is a bi-directional signal. As an output, PROCHOT# (Processor Hot) will go 

active when the processor temperature monitoring sensor detects that one or both 

cores has reached its maximum safe operating temperature. This indicates that the 

processor Thermal Control Circuit (TCC) has been activated, if enabled. As an input, 

assertion of PROCHOT# by the system will activate the TCC, if enabled, for both cores. 

The TCC will remain active until the system de-asserts PROCHOT#.

PROCHOT# will not be asserted (as an output) or observed (as an input) when the 

processor is in the Stop Grant, Sleep, Deep Sleep, and Deeper Sleep low-power states, 

hence the thermal solution must be designed to ensure the processor remains within 

specification. If the processor enters one of the above low-power states with 

PROCHOT# already asserted, PROCHOT# will remain asserted until the processor exits 

the low-power state and the processor DTS temperature drops below the thermal trip 

point.

PROCHOT# allows for some protection of various components from over-temperature 

situations. The PROCHOT# signal is bi-directional in that it can either signal when the 

processor (either core) 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. 

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. The system thermal design should allow the power delivery circuitry to operate 

within its temperature specification even while the processor is operating at its Thermal 

Design Power. With a properly designed and characterized thermal solution, it is 

anticipated that bi-directional PROCHOT# would only be asserted 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 Voltage Regulator Design Guide 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.