Thermal considerations, Thermal curves, Thermal testing setup – Delta Electronics DNQ12 User Manual
Page 9: Thermal derating, Figure 23: wind tunnel test setup
DS_DNQ12SIP25_07172008
9
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 height of this fan duct is constantly kept at
25.4mm (1’’).
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.
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
12.7 (0.5”)
MODULE
AIR FLOW
50.8 (2.0”)
FACING PWB
PWB
AIR VELOCITY
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
Figure 23:
Wind tunnel test setup
THERMAL CURVES
Figure 24:
Temperature measurement location
* The allowed maximum hot spot temperature is defined at 125℃.
DNQ12S0A0R25(standard) Output Current vs. Ambient Temperature and Air Velocity
@ Vin =12V, Vout =5V (Either Orientation)
0
5
10
15
20
25
30
25
35
45
55
65
75
85
Ambient Temperature (℃)
Output Current (A)
200LFM
600LFM
100LFM
300LFM
500LFM
Natural
Convection
400LFM
Figure 25:
Output current vs. ambient temperature and air
velocity@ Vin=12V, Vout=5V(Either Orientation)
DNQ12S0A0R25(standard) Output Current vs. Ambient Temperature and Air Velocity
@ Vin =12V, Vout =3.3V (Either Orientation)
0
5
10
15
20
25
30
25
35
45
55
65
75
85
Ambient Temperature (℃)
Output Current (A)
100LFM
500LFM
200LFM
400LFM
Natural
Convection
300LFM
Figure 26:
Output current vs. ambient temperature and air
velocity @ 12V, Vout=3.3V(Either Orientation)