Intel BX80619I73820, Design Manual

Page: 103 / 124

Thermal/Mechanical Specifications and Design Guide 103
Thermal Solutions
8.8.3 Fan Speed Control
When DTS (Digital Thermal Sensor) value is less than T
CONTROL
, the thermal profile can
be ignored. The DTS value is a relative temperature to PROCHOT, which is the
maximum allowable temperature before the thermal control circuit is activated. In this
region, the DTS value can be used to not only ensure specification compliance but also
to optimize fan speed control resulting in the lowest possible fan power and acoustics
under any operating conditions. When DTS goes above T
CONTROL
, fan speed must
increase to bring the sensor temperature below T
CONTROL
or to ensure compliance with
the Tcase profile.
The PECI command for DTS is GetTemp(). Through use of a sign bit, the value returned
from PECI is negative.
The PECI command for T
CONTROL
is RdPkgConfig(), Temperature Target Read, 15:8. The
value returned from PECI is unsigned (positive), however is negative by definition.
§
Figure 8-6. Processor Thermal Characterization Parameter Relationships
Table 8-4. Fan Speed Control, T
CONTROL
and DTS Relationship
Condition FSC Scheme
DTS ≤ T
CONTROL
FSC can adjust fan speed to maintain DTS ≤ T
CONTROL
(low acoustic region) and the
Tcase based thermal profile can be ignored.
DTS > T
CONTROL
FSC should adjust fan speed to keep T
CASE
at or below the Thermal Profile
specification (increased acoustic region) or increase fan speed to bring DTS below
T
CONTROL
.