Data Sheet

Thermal Management
90 Datasheet, Volume 1 of 2
PsysPL1 Tau: An averaging constant used for PsysPL1 exponential weighted moving
average (EWMA) power calculation.
The Psys signal and associated power limits / Tau are optional for the system
designer and disabled by default.
The Psys data will not include power consumption for charging.
5.1.3.3 Turbo Time Parameter (Tau)
Turbo Time Parameter (Tau) is a mathematical parameter (units of seconds) that
controls the Intel
®
Turbo Boost Technology 2.0 algorithm. During a maximum power
turbo event, the processor could sustain PL2 for a duration longer than the Turbo Time
Parameter. If the power value and/or Turbo Time Parameter is changed during runtime,
it may take some time based on the new Turbo Time Parameter level for the algorithm
to settle at the new control limits. The time varies depending on the magnitude of the
change, power limits, and other factors. There is an individual Turbo Time Parameter
associated with Package Power Control and Platform Power Control.
5.1.4 Configurable TDP (cTDP) and Low-Power Mode
Configurable TDP (cTDP) and Low-Power Mode (LPM) form a design option where the
processor's behavior and package TDP are dynamically adjusted to a desired system
performance and power envelope. Configurable TDP and Low-Power Mode technologies
offer opportunities to differentiate system design while running active workloads on
select processor SKUs through scalability, configuration and adaptability. The scenarios
or methods by which each technology is used are customizable but typically involve
changes to PL1 and associated frequencies for the scenario with a resultant change in
performance depending on system's usage. Either technology can be triggered by (but
are not limited to) changes in OS power policies or hardware events such as docking a
system, flipping a switch or pressing a button. cTDP and LPM are designed to be
configured dynamically and do not require an operating system reboot.
Note: Configurable TDP and Low-Power Mode technologies are not battery life improvement
technologies.
5.1.4.1 Configurable TDP
Note: Configurable TDP availability may vary between the different SKUs.
With cTDP, the processor is now capable of altering the maximum sustained power with
an alternate processor IA core base frequency. Configurable TDP allows operation in
situations where extra cooling is available or situations where a cooler and quieter
mode of operation is desired. Configurable TDP can be enabled using Intel's DPTF driver
or through HW/EC firmware. Enabling cTDP using the DPTF driver is recommended as
Intel does not provide specific application or EC source code.
cTDP consists of three modes as shown in the following table.