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.

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 21: Temperature measurement location

The allowed maximum hot spot temperature is defined at 110

℃

12.7 (0.5”)

MODULE

AIR FLOW

50.8 (2.0”)

FACING PWB

PWB

AIR VELOCITY

AND AMBIENT

TEMPERATURE

MEASURED BELOW

THE MODULE

0

50

100

150

200

250

300

350

400

25

35

45

55

65

75

85

95

105

Output Power (W)

Hot Spot Temperature(℃)

H48SN28012NR A (Standard) Output Power vs. Hot Spot Temperature

(Either Orientation)

H48SN28012_09262006

11

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

Figure 22: Output power vs. hot spot temperature (Either

Orientation)

Figure 20: Wind Tunnel Test Setup