JAW075B1 Lineage Power, JAW075B1 Datasheet - Page 11

• Manufacturer Part Number: JAW075B1
• Manufacturer: Lineage Power

April 2008
Thermal Considerations
Introduction
The temperature at this location should not exceed
100 °C. The output power of the module should not
exceed the rated power for the module as listed in the
Ordering Information table.
Although the maximum case temperature of the power
modules is 100 °C, you can limit this temperature to a
lower value for extremely high reliability.
Heat Transfer Without Heat Sinks
Increasing airflow over the module enhances the heat
transfer via convection. Figure 21 shows the maximum
power that can be dissipated by the module without
exceeding the maximum case temperature versus local
ambient temperature (T
through 3 m/s (600 ft./min.). Longitudinal orientation
occurs when the long direction of the module is parallel
to the airflow, whereas transverse orientation occurs
when the short direction of the module is parallel to the
airflow.
Note that the natural convection condition was mea-
sured at 0.05 m/s to 0.1 m/s (10 ft./min. to 20 ft./min.);
however, systems in which these power modules may
be used typically generate natural convection airflow
rates of 0.3 m/s (60 ft./min.) due to other heat-dissipat-
ing components in the system. The use of Figure 21 is
shown in the following example.
Example
What is the minimum airflow necessary for a
JAW075B1 operating at V
6.2 A, longitudinal orientation, and a maximum ambient
temperature of 50 °C?
Solution
Given: V
Determine P
Determine airflow (v) (Use Figure 21.):
Lineage Power
I
T
P
v = 1.0 m/s (200 ft./min.)
O
A
I
D
= 6.2 A
= 55 V
= 50 °C
= 11 W
D
(Use Figure 20.):
(continued)
A
) for natural convection
I
= 55 V, an output current of
(continued)
36 Vdc to 75 Vdc Input, 12 Vdc Output; 50 W to 75 W
Figure 19. JAW050B1 Power Dissipation vs.
Figure 20. JAW075B1 Power Dissipation vs.
10
14
12
10
9
8
7
6
5
4
3
2
8
6
4
2
0
0.4
0.6
Output Current
Output Current
0.9
1.4
1.4
OUTPUT CURRENT, I
OUTPUT CURRENT, I
2.2
1.9
3
2.4
3.8
2.9
O
O
4.6
(A)
(A)
3.4
V
V
V
I
I
I
= 75 V
= 55 V
= 36 V
V
V
V
I
I
I
= 75 V
= 55 V
= 36 V
5.4
3.9
8-3229 (F)
8-3230 (F)
6.2
4.4
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