101800F00000G Aavid Thermalloy, 101800F00000G Datasheet - Page 9
Manufacturer Part Number
Specifications of 101800F00000G
Size / Dimension
2 oz Tube
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
How to select a heat sink
The basic equation for heat transfer or power dissipation may be stated as follows:
P D =
P D = the power dissipated by the semiconductor device in watts.
ΔT = the temperature difference of driving potential which causes the flow of heat.
ΣR θ = the sum of the thermal resistances of the heat flow path across which ΔT exists.
The above relationship may be stated in the following forms:
T J –T A
P D =
P D =
R θJC + R θCS + R θSA
T J = the junction temperature in °C (maximum is usually stated by the manufacturer of the semiconductor device).
T C = case temperature of the semiconductor device in °C.
T S = temperature of the heat sink mounting surface in thermal contact with the semiconductor device in °C.
T A = ambient air temperature in °C.
R θJC = thermal resistance from junction to case of the semiconductor device in °C per watt
(usually stated by manufacturer of semiconductor device).
R θCS = thermal resistance through the interface between the semiconductor device
and the surface on which it is mounted in °C per watt.
R θSA = thermal resistance from mounting surface to ambient or thermal resistance of heat sink in °C per watt.
The above equations are generally used to determine the required thermal resistance of the heat sink (R θSA ),
since the heat dissipation, maximum junction and/or case temperature, and ambient temperature are known or set.
Figure 1 indicates the location of the various heat
flow paths, temperatures and thermal resistances.
Heat flow path mounting
surface to ambient, equation (3)
Heat flow path case
to ambient equation (2)
Heat flow path junction
to ambient, equation (1)
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How To Select a Heat Sink
T C –T A
P D =
R θCS + R θSA
The common practice is to represent the system with
a network of resistances in series as shown in Figure 2.
T S –T A
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