H48SC3R325_07122011
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’’).
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
12.7 (0.5”)
MODULE
IR FLO
50.8
2.0”
FACING PW
PWB
IR VELOCIT
ND AMBIEN
TEMPERATUR
MEASURED BELO
THE MODULE
Figure 20: Wind Tunnel Test Setup
Thermal Derating
Heat can be removed by increasing airflow over the module.
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 CURVES
Figure 21: Temperature measurement location
The allowed maximum hot spot temperature is defined at 116
℃
H48SC3R325(Standard) Output Current vs. Ambient Temperature and Air Velocity
@Vin = 48V (Either Orientation)
0
5
10
15
20
25
25 30 35 40 45 50 55 60 65 70 75 80 85
Natural
Convection
Ambient Temperature (℃)
Output Current (A)
Figure 22: Output current vs. ambient temperature and air
velocity @ V
in
=48V (Either Orientation)
