Vid-X; Processor Power Status Indicator (Psi-2) Signal - Intel P8700 - Core 2 Duo Processor Datasheet

Low Power Features
When in Intel Dynamic Acceleration Technology mode, it is possible for both cores to be
active under certain internal conditions. In such a scenario the processor may draw a
Instantaneous current (I
average I
refer to the Processor DC Specifications section for more details.
2.5

VID-x

The processor implements the VID-x feature for improved control of core voltage levels
when the processor enters a reduced power consumption state. VID-x applies only
when the processor is in the Intel Dynamic Acceleration Technology performance state
and one or more cores are in low-power state (i.e., CC3/CC4/CC6). VID-x provides the
ability for the processor to request core voltage level reductions greater than one VID
tick. The amount of VID tick reduction is fixed and only occurs while the processor is in
Intel Dynamic Acceleration Technology mode. This improved voltage regulator
efficiency during periods of reduced power consumption allows for leakage current
reduction which results in platform power savings and extended battery life.
When in Intel Dynamic Acceleration Technology mode, it is possible for both cores to be
active under certain internal conditions. In such a scenario the processor may draw a
Instantaneous current (I
average I
refer to the Processor DC Specifications section for more details.
2.6

Processor Power Status Indicator (PSI-2) Signal

The processor incorporates the PSI# signal that is asserted when the processor is in a
reduced power consumption state. PSI# can be used to improve intermediate and light
load efficiency of the voltage regulator, resulting in platform power savings and
extended battery life. The algorithm that the processor uses for determining when to
assert PSI# is different from the algorithm used in previous mobile processors. PSI-2
functionality is expanded further to support three processor states:
• Both cores are in idle state
• Only one core active state
• Both cores are in active state
PSI-2 functionality improves overall voltage regulator efficiency over a wide power
range based on the C-state and P-state of the two cores. The combined C-state and P-
state of both cores are used to dynamically predict processor power.
The real-time power prediction is compared against a set of predefined and configured
values of CHH and CHL. CHH is indicative of the active C-state of both the cores and
CHL is indicative that only one core is in active C-state and the other core is in low
power core state. PSI-2# output is asserted upon crossing these thresholds indicating
that the processor requires lower power. The voltage regulator will adapt its power
output accordingly. Additionally the voltage regulator may switch to a single phase and/
or asynchronous mode when the processor is idle and fused leakage limit is less than or
equal to the BIOS threshold value.
Datasheet
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