
10
Tyco Electronics Corp.
Data Sheet
November 2001
36 Vdc to 75 Vdc In; 3.3 Vdc and 5 Vdc Out; 16.5 W and 25
LUW025-Series Power Modules: dc-dc Converters:
Draft Copy Only
Lucent Technologies — Proprietary Use pursuant to Company instructions
Thermal Considerations (continued)
8-2603a
Note: Dimensions are in millimeters and (inches).
Figure 16. Thermal Test Setup
8-2788
Figure 17. TQ Temperature Measurement Location;
Top View; Orientation 1
8-2789
Figure 18. TQ Temperature Measurement Location;
Top View; Orientation 2
Convection Requirements for Cooling
To predict the approximate cooling needed for the mod-
ule, determine the power dissipated as heat by the unit
for the particular application. Figures
19—20 show typ-
ical heat dissipation for the module over a range of out-
put currents.
8-3026
Figure 19. LUW025F Power Dissipation vs. Output
Current, TA = 25 °C; Either Orientation
8-1888b
Figure 20. LUW025A Power Dissipation vs. Output
Current, TA = 25 °C; Either Orientation
With the known heat dissipation, module orientation
with respect to airflow, and a given local ambient tem-
perature, the minimum airflow can be chosen from the
derating curves in Figures
21—24.AIRFLOW
25.4 (1.0)
FOR AIR VELOCITY
AND AMBIENT
TEMPERATURE
MEASURE HERE
20
3.2
(
8
.0
)
76.2 (3.0)
AIRFLOW
THERMOCOUPLE
LOCATION T1
AIRFLOW
THERMOCOUPLE
LOCATION T1
1.00
3.00
4.00
0.00
OUTPUT CURRENT, IO (A)
3.00
2.00
5.00
6.00
5.00
0.40
1.00
PO
WER
DISSIP
A
T
ION,
P
D
(W)
4.00
2.00
VI = 75 V
VI = 48 V
VI = 36 V
8
7
5
4
0
0.5
1
1.5
2
4.5
5
OUTPUT CURRENT, IO (A)
PO
WER
DISSIP
A
TION,
P
D
(W)
2.5
3
3.5
4
3
2
1
6
VI = 75 V
VI = 48 V
VI = 36 V