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Sensor Based Thermal Specification Design Guidance
72 Thermal/Mechanical Specifications and Design Guidelines
Notes:
1. Ψ
CA
at “DTS = T
control
” is applicable to systems that has Internal Trise (Troom temperature to Processor
cooling fan inlet) of less than 10 °C. In case your expected Trise is grater than 10 °C a correction factor
should be used as explained below. For each 1 °C Trise above 10 °C, the correction factor CF is defined as
CF= 1.7 / Processor_TDP.
2. Example, For A Chassis Trise assumption of 12 °C for a 95W TDP processor.
CF = 1.7/95 W = 0.018/C
For Trise > 10 C
ΨCA at Tcontrol = Value listed in Column_2 - (Trise - 10) * CF
ΨCA = 0564 - (12 - 10) * 0.018 =0.528 C/W
In this case the fan speed should be set slightly higher equivalent to YCA=0.528C/W
Figure 8-3. DTS 1.1 Definition Points
Table 8-1. DTS 1.1 Thermal Solution Performance above T
CONTROL
Processor TDP
ψ
CA
at
DTS =
T
CONTROL
1,2
ψ
CA
at
DTS = -1 At
System
ambient_max=
40C
ψ
CA
at
DTS = -1 At
System
ambient_max=
45C
ψ
CA
at
DTS = -1 At
System
ambient_max=
50C
95W(no graphic) 0.569 0.354 0.300 0.248
95W(with graphic) 0.564 0.343 0.291 0.238
80W (no graphic) 0.620 0.364 0.300 0.238
45W(with graphic) 0.869 0.413 0.301 0.191
20W(no graphic) 3.713 1.875 1.625 1.375