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 Derating
Heat can be removed by increasing airflow over the module.
The module’s maximum case temperature is
95
℃
. 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.
Thermal Testing Setup
THERMAL CURVES
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’’).
Figure 20:
Temperature measurement location viewed from the
IMS side
The allowed maximum hot spot temperature is defined at 95
℃
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
12.7 (0.5”)
MODULE
AIR FLOW
50.8 (2.0”)
FACING PWB
PWB
AIR VELOCITY
AN
350
400
450
500
550
600
650
700
750
25
35
45
55
65
75
85
95
Output Power (W)
Hot spot Temperature(
℃
)
F48SA28025(Standard) Output Power vs. Hot Spot Temperature
(Either Orientation)
D AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
Figure 19:
Wind tunnel test setup
Figure 21:
Output power vs. hot spot temperature (Either
Orientation)
DS_F48SA28025_12072007
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