JFC050C Datasheet, PDF (14/20 Pages) Tyco Electronics – dc-dc Converters; 18 to 36 Vdc Input; 15 Vdc Output; 50 W to 100 W

JFC050C, JFC075C, JFC100C Power Modules:
dc-dc Converters; 18 to 36 Vdc Input, 15 Vdc Output; 50 W to 100 W
Data Sheet
October 1999
Thermal Considerations (continued)
Introduction (continued)
For additional information regarding this module, refer to
the Thermal Management JC-, JFC-, JW-, and JFW-
Series 50 W to 150 W Board-Mounted Power Modules
Technical Note (TN97-008EPS).
Heat Transfer Without Heat Sinks
Increasing airflow over the module enhances the heat
transfer via convection. Figure 19 shows the maximum
power that can be dissipated by the module without
exceeding the maximum case temperature versus local
ambient temperature (TA) for natural convection
through 4 m/s (800 ft./min.).
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 this power module may be
used typically generate a natural convection airflow
rate of 0.3 m/s (60 ft./min.) due to other heat dissipating
components in the system. The use of Figure 19 is
shown in the following example.
Example
What is the minimum airflow necessary for a JFC100C
operating at VI = 28 V, an output current of 6.7 A, and a
maximum ambient temperature of 40 °C?
Solution
Given: VI = 28 V
IO = 6.7 A
TA = 40 °C
Determine PD (Use Figure 21.):
PD = 15.5 W
Determine airflow (v) (Use Figure 19.):
v = 1.75 m/s (350 ft./min.)
35
4.0 m/s(800 ft./min.)
3.5 m/s(700 ft./min.)
30
3.0 m/s(600 ft./min.)
2.5 m/s(500 ft./min.)
25
2.0 m/s(400 ft./min.)
1.5 m/s(300 ft./min.)
20
1.0 m/s(200 ft./min.)
0.5 m/s(100 ft./min.)
15
10
5
0.1 m/s (NAT. CONV.)
(20 ft./min.)
0
0 10 20 30 40 50 60 70 80 90 100
LOCAL AMBIENT TEMPERATURE, TA (˚C)
8-1150 (C).a
Figure 19. Forced Convection Power Derating with
No Heat Sink; Either Orientation
10
9
8
7
6
5
VI = 36 V
4
VI = 28 V
VI = 18 V
3
2
1
0
0.0 0.5
1.0
1.5 2.0
2.5
3.0
OUTPUT CURRENT, IO (A)
8-1782 (C)
Figure 20. JFC050C Power Dissipation vs. Output
Current at 25 °C
14
Tyco Electronics Corp.