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Preliminary DS_NE12S20A_07272007
9
THERMAL CONSIDERATION
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.
THERMAL CURVES (NE12S0A0V20)
Hence, the choice of equipment to characterize the
thermal performance of the power module is a wind
tunnel.
Figure 25: Temperature measurement location* The allowed
maximum hot spot temperature is defined at 130
℃
NE12S0A0V20(standard) Output Current vs. Ambient Temperature and Air Velocity
@Vin=12V Vout=5.0V (Through PWB Orientation)
0
2
4
6
8
10
12
14
16
18
20
25 30 35 40 45 50 55 60 65 70 75 80 85
Natural
Convection
100LFM
200LFM
Ambient Tem
p
erature
(
℃
)
Output Current (A)
500LFM
400LFM
600LFM
300LFM
Figure 26: Output current vs. ambient temperature and air
velocity @Vin=12V, Vout=5.0V (Through PWB Orientation)
NE12S0A0V20(standard) Output Current vs. Ambient Temperature and Air Velocity
@Vin=12V Vout=2.5V (Through PWB Orientation)
0
2
4
6
8
10
12
14
16
18
20
25 30 35 40 45 50 55 60 65 70 75 80 85
Natural
Convection
100LFM
200LFM
Ambient Temperature (
℃
)
Output Current (A)
500LFM
400LFM
600LFM
300LFM
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.
MODULE
A
IR FLOW
11 (0.43”)
50.8 (2.0”)
FACING PWB
PWB
AIR VELOCITY
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
22 (0.87”)
Note: Wind tunnel test setup figure dimensions are in
millimeters and (Inches)
Figure 24: Wind tunnel test setup
Figure 27: Output current vs. ambient temperature and air
velocity@ Vin=12V, Vout=2.5V (Through PWB Orientation)