User Guide

Datasheet, Volume 1 of 2 101
Thermal Management
5.2.1.7 Fan Speed Control Scheme with Digital Thermal Sensor (DTS) 2.0
To simplify processor thermal specification compliance, the processor calculates the
DTS Thermal Profile from T
CONTROL
Offset, TCC Activation Temperature, TDP, and the
Thermal Margin Slope provided in the following table.
Note: TCC Activation Offset is 0 for the processors.
Using the DTS Thermal Profile, the processor can calculate and report the Thermal
Margin, where a value less than 0 indicates that the processor needs additional cooling,
and a value greater than 0 indicates that the processor is sufficiently cooled.
Refer to the processor Thermal Mechanical Design Guidelines (TMDG) for additional
information (see Related Documents).
Table 5-10. Digital Thermal Sensor (DTS) 1.1 Thermal Solution Performance Above
T
CONTROL
Processor
Ψ
CA
at DTS =
T
CONTROL
1, 2
At System
T
AMBIENT_MAX
= 30 °C
Ψ
CA
at DTS = -1
At System
T
AMBIENT_MAX
= 40 °C
Ψ
CA
at DTS = -1
At System
T
AMBIENT_MAX
= 45 °C
Ψ
CA
at DTS = -1
At System
T
AMBIENT_MAX
= 50 °C
Quad Core GT2
91W 0.45 0.26 0.21 0.15
65W 0.73 0.46 0.39 0.31
35W 1.57 0.74 0.60 0.46
Dual Core GT2 51W 0.83 0.48 0.38 0.28
35W 1.32 0.74 0.60 0.46
Quad Core GT1 65W 0.73 0.46 0.39 0.31
Dual Core GT1 54W 0.82 0.47 0.38 0.29
Notes:
1. Ψ
CA
at "DTS = T
CONTROL
" is applicable to systems that have an internal T
RISE
(T
ROOM
temperature to
Processor cooling fan inlet) of less than 10 °C. In case the expected T
RISE
is greater than 10°C, a
correction factor should be used as explained below. For each 1 °C T
RISE
above 10 °C, the correction
factor (CF) is defined as CF = 1.7 / (processor TDP)
2. Example: A chassis T
RISE
assumption is 12 °C for a 91 W TDP processor: CF = 1.7 / 91 W = 0.019 /W For
T
RISE
> 10 °C Ψ
CA
at T
CONTROL
= (Value provide in Column 2) – (T
RISE
– 10) * CF Ψ
CA
= 0.45 – (12 – 10)
0.019 = 0.41 °C/W In this case, the fan speed should be set slightly higher, equivalent to
Ψ
CA
= 0.41 °C/W