Package Specifications (Continued)
Example 1
Example 2
Assume P (max) = 5W and TA (max) = 40°C.
Assume P (max) = 10W and TA (max) = 40°C.
Therefore:
Therefore:
T
– T
T
– T
C
A
C
A
θ
θ
= ---------------------
θ
θ
= ---------------------
CA
CA
P
P
(85 – 40)
= ----------------------
5
(85 – 40)
= ----------------------
9
CA
CA
θ
= 9
θ
= 5
CA
CA
In this case, the heatsink under consideration is more than
adequate since at 5W worst case, it can maintain a 40°C
case temperature rise above ambient (θCA = 9) when a
maximum of 45°C (θCA = 8) is required.
In this case, the heatsink under consideration is NOT ade-
quate to maintain the 45°C case temperature rise above
ambient 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.
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