Datasheet
63
Thermal Management
5.2.1.3.2
Voltage Regulator Protection
PROCHOT# may be used for 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 will cool down as a result of reduced processor power
consumption. Bi-directional PROCHOT# can allow VR thermal designs to target thermal
design current (I
TDC
) 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. Overall, 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.
5.2.1.3.3
Thermal Solution Design and PROCHOT# Behavior
With a properly designed and characterized thermal solution, it is anticipated that
PROCHOT# will only be asserted for very short periods of time when running the most
power intensive applications. The processor performance impact due to these brief
periods of TCC activation is expected to be so minor that it would be immeasurable.
However, 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
•
Result in prolonged operation at or above the specified maximum junction
temperature and affect the long-term reliability of the processor
•
May be incapable of cooling the processor even when the TCC is active continuously
(in extreme situations)
5.2.1.3.4
Low-Power States and PROCHOT# Behavior
If the processor enters a low-power package idle state such as C3 or C6 with
PROCHOT# asserted, PROCHOT# will remain asserted until:
•
The processor exits the low-power state
•
The processor junction temperature drops below the thermal trip point
Note that the PECI interface is fully operational during all C-states and it is expected
that the platform continues to manage processor core thermals even during idle states
by regularly polling for thermal data over PECI.
5.2.1.4
On-Demand Mode
The processor provides an auxiliary mechanism that allows system software to force
the processor to reduce its power consumption via clock modulation. This mechanism is
referred to as “On-Demand” mode and is distinct from Adaptive Thermal Monitor and
