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 CURVES
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 height of this fan duct is constantly
kept at 25.4mm (1’’).
Figure 28:
Temperature measurement location
The allowed maximum hot spot temperature is defined at 125
℃
.
Output Current (A)
3.5
DNT12S0A0S03(standard) Output Current vs. Ambient Temperature and Air Velocity
@Vin = 12V,Vo=0.75V~5V (Either Orientation)
3.0
Natural
Convection
2.5
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.
FACING PWB
PWB
MODULE
2.0
1.5
1.0
0.5
0.0
25
30
35
40
45
50
55
60
65
70
75
80
85
Ambient Temperature (℃)
Figure 29:Output
current vs. ambient temperature and air
velocity@ Vin=12V, Vo=0.75V ~5.0V (Either Orientation)
AIR VELOCITY
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
AIR FLOW
50.8 (2.0”)
12.7 (0.5”)
25.4 (1.0”)
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches
Figure 27:
Wind tunnel test setup
DS_DNT12SMD03_06252007
9
DELTA [ DELTA ELECTRONICS, INC. ]
