JC050C1 Datasheet, PDF (12/16 Pages) Lineage Power Corporation – Distributed power architectures

JC050C, JC075C, JC100C Power Modules: dc-dc Converters;
18 Vdc to 36 Vdc Input, 15 Vdc Output; 50 W to 100 W
Data Sheet
March 2008
Thermal considerations (continued)
Heat Transfer Without Heat Sinks (continued)
18
16
14
VI = 18 V
12
VI = 28 V
VI = 36 V
10
8
6
4
2
0
0
1
2
3
4
5
6
OUTPUT CURRENT, IO (A)
Figure 23. JC100C Power Dissipation vs.
Output Current
7
8-1584 (C)
Heat Transfer with Heat Sinks
The power modules have through-threaded, M3 x 0.5
mounting holes, which enable heat sinks or cold plates
to attach to the module. The mounting torque must not
exceed 0.56 N-m (5 in.-lb.). For a screw attachment
from the pin side, the recommended hole size on the
customer’s PWB around the mounting holes is
0.130 ± 0.005 inches. If a larger hole is used, the
mounting torque from the pin side must not exceed
0.25 N-m (2.2 in.-lbs.).
Thermal derating with heat sinks is expressed by using
the overall thermal resistance of the module. Total
module thermal resistance (θca) is defined as the max-
imum case temperature rise (ΔTC, max) divided by the
module power dissipation (PD):
θca = ^Δ----^T---P-^C---^,-_D-^m----^a--^x- = -⁽--T----^C--P--^–---_D--T----^A---⁾-
The location to measure case temperature (TC) is
shown in Figure 20. Case-to-ambient thermal resis-
tance vs. airflow is shown, for various heat sink config-
urations and heights, in Figure 24. These curves were
obtained by experimental testing of heat sinks, which
are offered in the product catalog.
8
7
1 1/2 IN HEAT SINK
6
1 IN HEAT SINK
1/2 IN HEAT SINK
5
1/4 IN HEAT SINK
NO HEAT SINK
4
3
2
1
0
0
0.5
1.0
1.5
2.0
2.5 3.0
(100) (200) (300) (400) (500) (600)
AIR VELOCITY MEASURED IN m/s (ft./min.)
8-1153
Figure 24. Case-to-Ambient Thermal Resistance
Curves; Either Orientation
These measured resistances are from heat transfer
from the sides and bottom of the module as well as the
top side with the attached heat sink; therefore, the
case-to-ambient thermal resistances shown are gener-
ally lower than the resistance of the heat sink by itself.
The module used to collect the data in Figure 24 had a
thermal-conductive dry pad between the case and the
heat sink to minimize contact resistance. The use of
Figure 24 is shown in the following example
Example
If an 85 °C case temperature is desired, what is the
minimum airflow necessary? Assume the JC100C
module is operating at nominal line and an output cur-
rent of 6 A, maximum ambient air temperature of
40 °C, and the heat sink is 0.5 in.
12
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