Datasheet
61
Thermal Management
5.2.1.3.1
Bi-Directional PROCHOT#
By default, the PROCHOT# signal is defined as an output only. However, the signal may
be configured as bi-directional. When configured as a bi-directional signal, PROCHOT#
can be used for thermally protecting other platform components should they overheat
as well. When PROCHOT# is signaled externally:
•
The processor core will immediately reduce processor power to the minimum
voltage and frequency supported. This is contrary to the internally-generated
Adaptive Thermal Monitor response.
•
Clock modulation is not activated.
The TCC will remain active until the system deasserts PROCHOT#. The processor can
be configured to generate an interrupt upon assertion and deassertion of the
PROCHOT# signal.
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)
