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

Thermal Derating

Heat can be removed by increasing airflow over the module. The hottest point of the module is less than 106. 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 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’’).

 

 

Figure 21: Hot spot temperature measured point

 

 

 

 

The allowed maximum hot spot temperature is defined at 106

FACING PWB

PWB

 

 

 

 

 

 

 

 

 

 

 

E48SR15004(standard) Output Current vs. Ambient Temperature and Air Velocity

 

 

 

Output Current(A)

 

@Vin = 48V (Transverse Orientation)

 

 

 

 

MODULE

4.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.0

 

 

 

 

 

 

 

 

 

3.5

Natural

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Convection

 

 

 

 

 

 

 

 

3.0

 

 

 

 

 

 

 

AIR VELOCITY

 

 

 

100LFM

 

 

 

 

 

AND AMBIENT

 

2.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TEMPERATURE

 

 

 

 

200LFM

 

 

 

 

MEASURED BELOW

50.8 (2.0”)

2.0

 

 

 

 

 

 

 

THE MODULE

1.5

 

 

 

300LFM

 

 

 

 

 

 

 

 

 

 

 

 

 

AIR FLOW

 

 

 

 

400LFM

 

 

 

 

 

1.0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.5

 

 

 

 

 

 

 

 

12.7 (0.5”)

0.0

 

 

 

 

 

 

 

 

 

50

55

60

65

70

75

80

85

 

 

 

 

 

 

 

 

Ambient Temperature ()

Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)

Figure 20: Wind tunnel test setup

Figure 22: Output current vs. ambient temperature and air

velocity@Vin=48V(Transverse Orientation)

 

DS_E48SR15004_05222008

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Delta Electronics E48SR manual Thermal Considerations, Thermal Curves, Thermal Testing Setup Thermal Derating