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THERMAL CONSIDERATIONS
Thermal management is an important part of the system
PWB
FACING PWB
design. To ensure proper, reliable operation, sufficient
cooling of the power module is needed over the entire
MODULE
temperature range of the module. Convection cooling is
usually the dominant mode of heat transfer.
Hence, the choice of equipment to characterize the
AIR VELOCITY
thermal performance of the power module is a wind
AND AMBIENT
tunnel.
TEMPERATURE
MEASURED BELOW
50.8 (2.0")
THE MODULE
Thermal Testing Setup
AIR FLOW
Delta's DC/DC power modules are characterized in
heated vertical wind tunnels that simulate the thermal
10 (0.4")
environments
encountered
in
most
electronics
equipment. This type of equipment commonly uses
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
vertically mounted circuit cards in cabinet racks in which
Figure 19: Wind tunnel test setup
the power modules are mounted.
The
following
figure
shows
the
wind
tunnel
characterization setup. The power module is mounted
on a test PWB and is vertically positioned within the
wind tunnel. The space between the neighboring PWB
and the top of the power module or a heat sink is
6.35mm (0.25").
Thermal Derating
Heat can be removed by increasing airflow over the
module. Figure 13 and 14 show maximum output is a
function of ambient temperature and airflow rate. The
module's maximum case temperature is +100°C.
To
enhance system reliability, the power module should
always be operated below the maximum operating
temperature. If the temperature exceeds the maximum
module temperature, reliability of the unit may be
affected.
9
DS_s48SS12001_06082006
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