Sensor Based Thermal Specification Design Guidance
58 Thermal/Mechanical Specifications and Design Guidelines
7.6 Thermal Solution Characterization
Table 7-1 is early engineering data on the RCBF7-1156 (DHA-A) thermal solution as a
reference for the development of thermal solutions and the fan speed control
algorithm.
Notes:
1. The ambient temperature is measured at the inlet to the processor thermal solution
2. This column can be expressed as a function of T
AMBIENT
by the following equation:
Ψ
CA
= 0.29 + (45.1 - T
AMBIENT
) x 0.0181
3. This column can be expressed as a function of T
AMBIENT
by the following equation:
Ψ
CA
= 0.29 + (45.1 - T
AMBIENT
) x 0.0105
4. This table is provided as a reference please consult the product specification for current values.
5. Based on the testing performed a curve was fit to the data in the form
Psi_ca = a x RPM
3
+b x RPM
2
+c x RPM + d, where:
a = -1.53 E-11, b = 1.41 E-07, c = -0.00048, d = 0.925782
6. Full Speed of 3150 RPM the DHA-A thermal solution delivers a Ψ
CA
= 0.335 °C /W based on preliminary
testing.
7. Minimum speed is limited to 1000 RPM to ensure cooling of other system components
§
Table 7-1. Thermal Solution Performance above T
CONTROL
T
AMBIENT
1
Ψ
CA
at
DTS = T
CONTROL
2
RPM for Ψ
CA
at
DTS = T
CONTROL
5
Ψ
CA
at
DTS = -1
3
RPM for Ψ
CA
at
DTS = -1
5
45.1 0.290 N/A 0.290 N/A
44.0 0.310 N/A 0.301 N/A
43.0 0.328 N/A 0.312 N/A
42.0 0.346 2950 0.322 N/A
41.0 0.364 2600 0.333 N/A
40.0 0.383 2300 0.343 3150
39.0 0.401 2100 0.354 2750
38.0 0.419 1900 0.364 2600
37.0 0.437 1750 0.375 2400
36.0 0.455 1650 0.385 2250
35.0 0.473 1500 0.396 2150
34.0 0.491 1400 0.406 2050
33.0 0.510 1350 0.417 1900
32.0 0.528 1200 0.427 1850
31.0 0.546 1150 0.438 1750
30.0 0.564 1050 0.448 1650
29.0 0.582 1000 0.459 1600
28.0 0.600 1000 0.469 1550
27.0 0.618 1000 0.480 1450
26.0 0.637 1000 0.491 1400
25.0 0.655 1000 0.501 1350
24.0 0.673 1000 0.512 1300
23.0 0.691 1000 0.522 1250
22.0 0.709 1000 0.533 1200
21.0 0.727 1000 0.543 1150
20.0 0.746 1000 0.554 1100
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