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PID7t-603e Hardware Specifications
System Design Information
Figure 18. Thermalloy #2328B Heat Sink-to-Ambient Thermal Resistance Versus Airflow Velocity
Assuming an air velocity of 0.5 m/s, we have an effective Rsa of 7 C/W, thus
Tj = 30C + 5C + (0.095 C/W +1.0 C/W + 7 C/W) * 3.0 W,
resulting in a die-junction temperature of approximately 60 C which is well within the maximum operating
temperature of the component.
For a PBGA package, and assuming a Ta of 30 C, a Tr of 5 C a PBGA package qjc = 8, and a power
consumption (Pd) of 3.0 Watts, the following expression for Tj is obtained:
Die-junction temperature: Tj = 30 C + 5 C + (8 C/W + 1.0 C/W + Rsa) * 3.0 W
Assuming an air velocity of 0.5 m/s, we have an effective Rsa of 7 C/W, thus
Tj = 30C + 5C + (8 C/W +1.0 C/W + 7 C/W) * 3.0 W,
resulting in a die-junction temperature of approximately 83 C which is well within the maximum operating
temperature of the component.
Other heat sinks offered by Chip Coolers, IERC, Thermalloy, Wakeeld Engineering, and Aavid
Engineering offer different heat sink-to-ambient thermal resistances, and may or may not need air ow.
Though the die junction-to-ambient and the heat sink-to-ambient thermal resistances are a common
gure-of-merit used for comparing the thermal performance of various microelectronic packaging
technologies, one should exercise caution when only using this metric in determining thermal management
because no single parameter can adequately describe three-dimensional heat ow. The nal die-junction
operating temperature, is not only a function of the component-level thermal resistance, but the system-level
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5
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8
0
0.5
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1.5
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3.5
Thermalloy #2328B Pin-fin Heat Sink
Approach Air Velocity (m/s)
Heat
Sink
Thermal
Resistance
(C/W)
(25 x28 x 15 mm)
2
4
6