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Data Sheet
April 2008
Lineage Power
11
36 Vdc to 75 Vdc Input; 25 W
CW025 Dual Output-Series Power Modules:
Thermal Considerations
8-866(C).a
Note: Dimensions are in millimeters and (inches). Drawing is not to scale.
Figure 15. Thermal Test Setup
50.8
(2.00)
12.7 (0.50)
101.6
(4.00)
203.2 (8.00)
AIRFLOW
MEASURE CASE
TEMPERATURE AT
CENTER OF UNIT
CONNECTORS TO
LOADS, POWER
SUPPLIES, AND
DATALOGGER,
6.35 (0.25) TALL
203.2
(8.00)
9.7 (0.38)
19.1 (0.75)
WIND TUNNEL WALL
AIR VELOCITY PROBE
AMBIENT TEMPERATURE
THERMOCOUPLE
AIR-
FLOW
The 25 W dual output power modules are designed to
operate in a variety of thermal environments. As with
any electronic component, sufcient cooling must be
provided to help ensure reliable operation of the unit.
Heat-dissipating components inside the module are
thermally coupled to the case. Heat is removed by con-
duction, convection, and radiation to the surrounding
environment.
The thermal data presented is based on measure-
ments taken in a wind tunnel. The test setup shown in
Figure 15 was used to collect data. Actual performance
can vary depending on the particular application
environment.
Basic Thermal Performance
The CW025 Dual Output-Series Power Modules have a
separate power stage for each of the outputs. This
means that the maximum operating temperature can
be predicted quite closely by treating each output indi-
vidually and then summing
the results. Figures 16
through 19 are used to predict the safe operating con-
dition for many different operating and environmental
conditions.
The method used to determine the maximum ambient
temperature at a given air velocity is a four-step pro-
cess:
1.
Find the power dissipated for output 1 by using the
particular output condition (IO1).
2.
Repeat step 1 for
output 2 using Figures 16
through 18.
3.
Find the total power dissipated by summing the
power dissipated on each of the outputs: (PDout1 +
PDout2) = PDtotal
4.
determine the maximum ambient temperature at
different air velocities.