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’’).

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 20: Hot spot temperature measured point

 

 

 

The allowed maximum hot spot temperature is defined at 110

FACING PWB

PWB

 

 

 

 

 

 

 

 

 

S48SP3R310(Standard)

Output Load vs. Ambient Temperature and Air Velocity

 

MODULE

 

Output Current(A)

@Vin=48V (Either Orientation)

 

 

 

11

 

 

 

 

 

 

10

 

 

 

 

 

 

 

9

Natural

 

 

 

 

 

 

 

Convection

 

 

 

 

 

 

8

 

 

 

 

 

AIR VELOCITY

 

7

100LFM

 

 

 

 

AND AMBIENT

 

6

 

 

 

 

 

TEMPERATURE

 

200LFM

 

 

 

 

 

 

 

 

MEASURED BELOW

 

5

 

300LFM

400LFM

 

 

50.8 (2.0”)

 

 

 

 

THE MODULE

4

 

 

500LFM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AIR FLOW

3

 

 

600LFM

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

1

 

 

 

 

 

 

12.7 (0.5”)

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60

65

70

75

80

85

 

 

 

 

 

 

 

Ambient Temperature ()

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

Figure 19: Wind tunnel test setup

Figure 21: Output load vs. ambient temperature and air

velocity@Vin=48V (Either Orientation)

DS_S48SP3R310_05222008

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Delta Electronics Series S48SP manual Thermal Considerations, Thermal Curves, Thermal Testing Setup, Thermal Derating