GX1 Datasheet, PDF (209/247 Pages) National Semiconductor (TI) – Processor Series Low Power Integrated x86 Solution

Package Specifications (Continued)
Example 1
Assume P (max) = 5W and T_A (max) = 40°C.
Therefore:
θ_CA = -^T---^C------_P^–-----T----^A--
θ_CA = ⁽---8---5----–5-----4---0----⁾
Example 2
Assume P (max) = 10W and T_A (max) = 40°C.
Therefore:
θ_CA = -^T---^C------_P^–-----T----^A--
θ_CA = ⁽---8---5----–9-----4---0----⁾
θ_CA = 9
θ_CA = 5
The heatsink must provide a thermal resistance below
9°C/W. In this case, the heatsink under consideration is
more than adequate since at 5W worst case, it can limit the
case temperature rise above ambient to 40°C (θ CA = 8).
In this case, the heatsink under consideration is NOT ade-
quate to limit the case temperature rise above ambient to
45°C for a 9W processor.
For more information on thermal design considerations or
heatsink properties, refer to the Product Selection Guide of
any leading vendor of thermal engineering solutions.
Revision 1.0
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