THERMAL CONSIDERATIONS
Thermal Derating
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
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
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 |
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characterization setup. The power module is mounted | Figure 21: | Hot spot temperature measured point | ||||||||||||||
on a test PWB and is vertically positioned within the | ||||||||||||||||
The allowed maximum hot spot temperature is defined at 118℃ | ||||||||||||||||
wind tunnel. The space between the neighboring PWB | ||||||||||||||||
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and the top of the power module is constantly kept at |
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6.35mm (0.25’’). |
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| Output Current(A) | E24SR05012(Standard) | Output Current vs. Ambient Temperature and Air Velocity | |||||
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| @Vin = 24V (Transverse Orientation) | ||||||||
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| 12 |
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| Natural |
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FACING PWB |
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| PWB | 10 |
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| Convection |
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| MODULE |
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| 8 |
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| 100LFM |
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| 200LFM |
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| 6 |
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AIR VELOCITY |
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| 4 |
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AND AMBIENT |
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TEMPERATURE |
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| 2 |
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MEASURED BELOW |
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| 50.8 (2.0”) |
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THE MODULE |
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| AIR FLOW |
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| 0 |
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| 25 30 | 35 40 45 | 50 55 60 65 70 75 80 85 | ||||||||
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| Ambient Temperature (℃) | ||
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| Figure 22: Output current vs. ambient temperature and air velocity | |||||||
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| 12.7 (0.5”) | @Vin=24V (Transverse Orientation) | ||||||||
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Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
Figure 20: Wind tunnel test setup
DS_E24SR05012_01032008 | 10 |