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 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
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’’).
Figure 21:
Hot spot temperature measured point
The allowed maximum hot spot temperature is defined at 125
℃
Output Current(A)
E24SR12005(Standard) Output Current vs. Ambient Temperature and Air Velocity
@Vin = 24V (Transverse Orientation)
5
FACING PWB
PWB
MODULE
4
Natural
Convection
3
2
AIR VELOCITY
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
AIR FLOW
1
50.8 (2.0”)
0
25
30
35
40
45
50
55
60
65
70
75
80
85
Ambient Temperature (℃)
Figure 22:
Output current vs. ambient temperature and air velocity
@V
in
=24V (Transverse Orientation)
12.7 (0.5”)
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
Figure 20:
Wind tunnel test setup figure
DS_E24SR12005_ 01182007
10
DELTA [ DELTA ELECTRONICS, INC. ]
