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 height of this fan duct is constantly kept at 25.4mm (1’’).
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 32: Temperature measurement location
The allowed maximum hot spot temperature is defined at 125℃
DNT04S0A0R03(standard) Output Current vs. Ambient Temperature and Air Velocity
Output Current (A) | @Vin=5V Vout=0.75~3.3V (Through PCB Orientation) | |
3.5 | ||
|
3.0
Natural
Convection
2.5
2.0
1.5
1.0
0.5
0.0
25 | 30 | 35 | 40 | 45 | 50 | 55 | 60 | 65 | 70 | 75 | 80 | 85 |
|
|
|
|
|
|
|
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|
| Ambient Temperature (℃) | ||
Figure 33: Output current vs. ambient temperature and air velocity @ Vin=5V, Vout=0.75V~3.3V(Through PCB Orientation)
FACING PWB
AIR VELOCITY
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
PWB
MODULE
50.8 (2.0”)
AIR FLOW
12.7 (0.5”) 
25.4 (1.0”)
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
Figure 31: Wind tunnel test setup
DS_DNT04SIP3A_09262007
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