JAHW075A Lineage Power, JAHW075A Datasheet - Page 13

• Manufacturer Part Number: JAHW075A
• Manufacturer: Lineage Power

April 2008
Feature Descriptions
Output Overvoltage Protection
The output overvoltage protection consists of circuitry
that monitors the voltage on the output terminals. If the
voltage on the output terminals exceeds the overvolt-
age protection threshold, then the module will shut
down and attempt to restart. A latch-ff option is also
available.*
Overtemperature Protection
To provide protection in a fault condition, the unit is
equipped with an overtemperature circuit. In a event of
such a fault, the module enters into an auto-restart
“hiccup” mode with low output voltage until the fault is
removed. Recovery from the overtemperature protec-
tion is automatic after the unit cools below the overtem-
perature protection threshold. A latch-ff option is also
available.*
* Protection latch-off causes the ouput to be disabled until input
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 27.
Note: Top view, pin locations are for reference only. Measurements
Figure 27. Case Temperature Measurement
Lineage Power
power is recyeled or until the remote on-off is recycled off-on.
(1.20)
shown in millimeters and (inches).
30.5
Location
V
ON/OFF
CASE
V
I
I
(1.14)
(+)
(–)
29.0
+ SEN
– SEN
V
TRIM
V
O
O
(+)
(–)
(continued)
dc-dc Converters; 36 to 75 Vdc Input, 5 Vdc Output; 50 to 100 W
MEASURE CASE
TEMPERATURE HERE
8-716 (F).h
C
)
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 28 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 28 is
shown in the following example.
Example
What is the minimum airflow necessary for a
JAHW075A operating at V
15 A, and a maximum ambient temperature of 55 °C?
Solution
Given: V
Determine P
Determine airflow (v) (Use Figure 28.):
I
T
P
v = 0.5 m/s (100 ft./min.)
O
A
I
D
= 55 V
= 15 A
= 55 °C
= 8 W
D
(Use Figure 31.):
A
) for natural convection
I
= 55 V, an output current of
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