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 21: Temperature measurement location

The allowed maximum hot spot temperature is defined at 121℃.

FACING PWB

AIR VELOCITY

AND AMBIENT

TEMPERATURE

MEASURED BELOW

THE MODULE

PWB

MODULE

50.8 (2.0”)

AIR FLOW

12.7 (0.5”)

V48SR15004(standard)	Output Current vs. Ambient Temperature and Air Velocity
Output Current (A)	@Vin = 48V (Either Orientation)
5
4	Natural
	Convection

100LFM

200LFM

300LFM

400LFM

500LFM

600LFM

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 (Either Orientation)

DS_V48SR15004_06122007