JW100D Lineage Power, JW100D Datasheet - Page 13

• Manufacturer Part Number: JW100D
• Manufacturer: Lineage Power

April 2008
Thermal Considerations
Introduction
The power modules operate in a variety of thermal
environments; however, sufficient cooling should be
provided to help ensure reliable operation of the unit.
Heat-dissipating components inside the unit are ther-
mally coupled to the case. Heat is removed by conduc-
tion, convection, and radiation to the surrounding
environment. Proper cooling can be verified by mea-
suring the case temperature. Peak temperature (T
occurs at the position indicated in Figure 26.
Note: Top view, pin locations are for reference only.
Figure 26. Case Temperature Measurement
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.
For additional information on these modules, refer to
the Thermal Management JC-, JFC-, JW-, and JFW-
Series 50 W to 150 W Board-Mounted Power Modules
Technical Note
(TN97-008EPS).
Lineage Power
Measurements shown in millimeters and (inches).
7.6 (0.3)
Location
V
ON/OFF
CASE
V
I
I
38.0 (1.50)
(+)
(–)
dc-dc Converters; 36 to 75 Vdc Input, 2 Vdc Output; 20 W to 60 W
+ SEN
– SEN
V
V
TRIM
O
O
(–)
(+)
MEASURE CASE
TEMPERATURE HERE
8-716 (C).d
C
)
Heat Transfer Without Heat Sinks
Increasing airflow over the module enhances the heat
transfer via convection. Figure 27 shows the maximum
power that can be dissipated by the module without
exceeding the maximum case temperature versus local
ambient temperature (T
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 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 27 is
shown in the following example.
Example
What is the minimum airflow necessary for a JW100D
operating at V
maximum ambient temperature of 40 °C?
Solution
Given: V
Determine P
Determine airflow (v) (Use Figure 27.):
Figure 27. Forced Convection Power Derating with
35
30
25
20
15
10
5
0
I
T
P
v = 1.5 m/s (300 ft./min.)
O
0
A
I
D
= 54 V
= 20 A
= 40 °C
No Heat Sink; Either Orientation
= 14.3 W
0.1 m/s (NAT. CONV.)
10
D
I
(Use Figure 30.):
LOCAL AMBIENT TEMPERATURE, T
= 54 V, an output current of 20 A, and a
20
(20 ft./min.)
30
A
) for natural convection
40
50
60
4.0 m/s (800 ft./min.)
3.5 m/s (700 ft./min.)
3.0 m/s (600 ft./min.)
2.5 m/s (500 ft./min.)
2.0 m/s (400 ft./min.)
1.5 m/s (300 ft./min.)
1.0 m/s (200 ft./min.)
0.5 m/s (100 ft./min.)
70
A
80
(°C)
90
8-1150 (C).a
100
13