DS_Q48SP12017_05302008
10
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 pending to release and the measured location is
illustrated in Figure 22. 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 (Inches)
12.7 (0.5”)
MODULE
A
IR FLOW
50.8
(
2.0”
)
FACING PWB PWB
AIR VELOCIT
Y
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
Fi
g
ure 21: Wind tunnel test setu
p

THERMAL CURVES
Figure 22: Temperature measurement location
The allowed maximum hot spot temperature is defined at 120
℃
Q48SP12017(Standard) Output Current vs. Ambient Temperature and Air Velocity
@Vin = 48V (Transverse Orientation)
0
2
4
6
8
10
12
14
16
18
20
20 25 30 35 40 45 50 55 60 65 70 75 80 85
Ambient Temperature (℃)
Output Current(A)
Natural
Convection
400LFM
500LFM
600LFM
100LFM
200LFM
300LFM
Figure 23: Output current vs. ambient temperature and air
velocity@ Vin=48V (Transverse orientation)