DS_E48SC12008_03192012

11

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’’).

AIR FLOW

MODULE

PWB

AIR VELOCITY

AND AMBIENT

TEMPERATURE

SURED BELOW

THE MODULE

FANCING PWB

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

Figure 18: Wind tunnel test setup

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.