Delta Electronics Q48SR - Manual (Page 11)

THERMAL CONSIDERATIONS
Thermal management is an important part of the
system design. To ensure proper, reliable operation,
sufficient cooling of the power module is needed over
the entire temperature range of the module. Convection
cooling is usually the dominant mode of heat transfer.
Hence, the choice of equipment to characterize the
thermal performance of the power module is a wind
tunnel.
Thermal Testing Setup
Delta’s DC/DC power modules are characterized in
heated vertical wind tunnels that simulate the thermal
environments encountered in most electronics
equipment. This type of equipment commonly uses
vertically mounted circuit cards in cabinet racks in which
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 is constantly kept at
6.35mm (0.25’’).
Thermal Derating
Heat can be removed by increasing airflow over the
module. The module’s maximum hot spot temperature
is 120 degrees C at 80% load and the measured
location is illustrated in Figure 18. 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.
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inche
12.7 (0.5”)
MODULE
AIR FLOW
50.8 (2.0”)
FACING PWB PWB
AIR VELOCITY
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
Figure 23:
Wind tunnel test setup figure dimensions are in
millimeters and (inches)