DS_Q48DC12003_03112008
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.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
IR FLOW
50.8
2.0”
FACING PWB
PWB
AIR VELOCIT
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
Figure 19: Wind Tunnel Test Setup
THERMAL CURVES
Figure 20: Temperature measurement location
* The allowed maximum hot spot temperature is defined at 124
℃
Q48DC12003(Standard) Output Current vs. Ambient Temperature and Air Velocity
@Vin = 48V (Transverse Orientation)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
25 30 35 40 45 50 55 60 65 70 75 80 85
Ambient Temperature (℃)
Output Current(A)
Natural
Convection
200LFM
100LFM
Figure 21: Output current vs. ambient temperature and air velocity
@V
in
= 48V(Transverse Orientation)
