JW075R Lineage Power, JW075R Datasheet - Page 15

• Manufacturer Part Number: JW075R
• Manufacturer: Lineage Power

April 2008
Feature Descriptions
Overtemperature Protection
The 100 W and 150 W modules feature an overtemper-
ature protection circuit to safeguard against thermal
damage.
The circuit shuts down the module when the maximum
case temperature is exceeded. The module restarts
automatically after cooling.
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 35.
Note: Top view, pin locations are for reference only.
Figure 35. 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.
Lineage Power
7.6 (0.3)
Measurements shown in millimeters and (inches).
Location
V
ON/OFF
CASE
V
I
I
38.0 (1.50)
(+)
(–)
(continued)
dc-dc Converters; 36 to 75 Vdc Input, 28 Vdc Output; 50 W to 150
+ SEN
– SEN
V
V
TRIM
O
O
(–)
(+)
MEASURE CASE
TEMPERATURE HERE
8-716 (C).f
C
)
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).
Heat Transfer Without Heat Sinks
Increasing airflow over the module enhances the heat
transfer via convection. Figure 36 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 36 is
shown in the following example.
Example
What is the minimum airflow necessary for a JW150R1
operating at V
maximum ambient temperature of 40 °C?
Solution
Given: V
Determine P
Determine airflow (v) (Use Figure 36.):
I
T
P
v = 1.6 m/s (320 ft./min.)
O
A
I
D
= 48 V
= 5.3 A
= 40 °C
= 14.8 W
D
I
(Use Figure 40.):
= 48 V, an output current of 5.3 A, and a
A
) for natural convection
15