Data Sheet

Thermal Management
92 Datasheet, Volume 1 of 2
5.1.5 Thermal Management Features
Occasionally the processor may operate in conditions that are near to its maximum
operating temperature. This can be due to internal overheating or overheating within
the platform. In order to protect the processor and the platform from thermal failure,
several thermal management features exist to reduce package power consumption and
thereby temperature in order to remain within normal operating limits. Furthermore,
the processor supports several methods to reduce memory power.
5.1.5.1 Adaptive Thermal Monitor
The purpose of the Adaptive Thermal Monitor is to reduce processor IA core power
consumption and temperature until it operates below its maximum operating
temperature. Processor IA core power reduction is achieved by:
• Adjusting the operating frequency (using the processor IA core ratio multiplier) and
voltage.
• Modulating (starting and stopping) the internal processor IA core clocks (duty
cycle).
The Adaptive Thermal Monitor can be activated when the package temperature,
monitored by any digital thermal sensor (DTS), meets its maximum operating
temperature. The maximum operating temperature implies maximum junction
temperature Tj
MAX
.
Reaching the maximum operating temperature activates the Thermal Control Circuit
(TCC). When activated the TCC causes both the processor IA core and graphics core to
reduce frequency and voltage adaptively. The Adaptive Thermal Monitor will remain
active as long as the package temperature remains at its specified limit. Therefore, the
Adaptive Thermal Monitor will continue to reduce the package frequency and voltage
until the TCC is de-activated.
Tj
MAX
is factory calibrated and is not user configurable. The default value is software
visible in the TEMPERATURE_TARGET (0x1A2) MSR, bits [23:16].
The Adaptive Thermal Monitor does not require any additional hardware, software
drivers, or interrupt handling routines. It is not intended as a mechanism to maintain
processor thermal control to PL1 = TDP. The system design should provide a thermal
solution that can maintain normal operation when PL1 = TDP within the intended usage
range.
Adaptive Thermal Monitor protection is always enabled.
5.1.5.1.1 TCC Activation Offset
TCC Activation Offset can be set as an offset from the maximum allowed component
temperature to lower the onset of TCC and Adaptive Thermal Monitor. In addition, the
processor has added an optional time window (Tau) to manage processor performance
at the TCC Activation offset value via an EWMA (Exponential Weighted Moving Average)
of temperature.
TCC Activation Offset with Tau=0
An offset (degrees Celsius) can be written to the TEMPERATURE_TARGET (0x1A2) MSR,
bits [29:24], the offset value will be subtracted from the value found in bits [23:16].
When the time window (Tau) is set to zero, there will be no averaging, the offset, will