Vicor VI-J00 Family DC-DC Converters and Configurable Power Supplies - Manual (Page 68)

Design Guide & Applications Manual
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies
VI-200 and VI-J00 Family Design Guide Rev 3.5 vicorpower.com
Page 67 of 98
Apps. Eng. 800 927.9474 800 735.6200
Example 3. Determine the maximum ambient temperature
of a 3-up FlatPAC delivering 12 V at 600 W in 500 LFM
with no additional conduction cooling to the chassis.
Maximum ambient temp. = T
max
–
θ
sa
x P
out
( 1
– 1
)
η
T max = 85°C
θ
sa = 0.3°C/W
P out = 600 W
η = 85% = (0.85)
Maximum ambient temp. = 85 – 0.3 x 600
( 1
– 1
)
0.85
= 53°C
Example 4. Determine the temperature rise of a
150 W, VI-200 converter delivering 5 V at 132 W
with a Part #30090 heat sink in 200 LFM.
Temperature rise =
θ
sa x P out
( 1
– 1
)
η
θ
sa
= 1.1°C/W
P out = 132 W
η = 81% = (0.81)
Temperature rise = 1.1 x 132
( 1
– 1
)
0.81
= 34˚C Over ambient temperature
Example 5. Determine the baseplate to coldplate thermal
drop for an MI-200 converter delivering 5 V at 50 W with
a thermal pad.
Thermal drop =
θ
bs x P out
( 1
– 1
)
η
θ
bs
= 0.2°C/W
P out = 50 W
η = 81% = 0.81
Temperature rise = 0.2 x 50
( 1
– 1
)
0.81
= 2.34˚C
20. Thermal and Module Mounting Considerations