DS_
T48SR05005_09282012
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’’).
AIR FLOW
MODU LE
PW B
50.8(2.00")
AIR VELOCITY
AND AM BI ENT
TEMPERATURE
SURED BELOW
THE MODULE
FAN CING PW B
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
Figure 23: 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
NTC RESISTOR
AIRFLOW
HOT SPOT
Figure 24: * Hot spot& NTC resistor temperature measured
points.
T48SR05005(Standard) Output Current vs. Ambient Temperature and Air Velocity
@Vin = 48V (Either Orientation)
0. 0
0. 5
1. 0
1. 5
2. 0
2. 5
3. 0
3. 5
4. 0
4. 5
5. 0
25 30 35 40 45 50 55 60 65 70 75 80 85
Ambient Temperature (
℃
)
Output Curre nt (A)
Natural
Co nvecti on
100LFM
Figure 25: Output current vs. ambient temperature and air
velocity @Vin=48V(Either orientation)
