JBW050A Power Modules: dc-dc Converter;
36 to 75 Vdc Input, 5 Vdc Output; 50 W
Data Sheet
March 27, 2008
Feature Descriptions (continued)
Thermal Considerations
Introduction
Output Voltage Set-Point Adjustment
(Trim) (continued)
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 (TC)
occurs at the position indicated in Figure 17.
VI(+)
VO(+)
ON/OFF SENSE(+)
Radj-up
CASE
VI(–)
TRIM
SENSE(–)
VO(–)
RLOAD
38.0 (1.50)
8-715b
Figure 15. Circuit Configuration to Increase
Output Voltage
VI(+)
VO(+)
10M
38.0
(1.50)
ON/OFF
+ SEN
TRIM
MEASURE CASE
TEMPERATURE
HERE
1M
CASE
VI(–)
– SEN
VO(–)
100k
10k
8-716.f
Note: Top view, pin locations are for reference only.
Measurements shown in millimeters and (inches).
0
2
4
6
8
10
Figure 17. Case Temperature Measurement
Location
%
CHANGE IN OUTPUT VOLTAGE (Δ%)
8-880.a
Figure 16. Resistor Selection for Increased Output
Voltage
The maximum temperature per Figure 17 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.
Output Overvoltage Protection
Although the maximum case temperature of the power
modules is 90 °C to 100 °C, you can limit this tempera-
ture to a lower value for extremely high reliability.
The output overvoltage clamp consists of control cir-
cuitry, independent of the primary regulation loop, that
monitors the voltage on the output terminals. The con-
trol loop of the clamp has a higher voltage set point
than the primary loop (see Feature Specifications
table). This provides a redundant voltage control that
reduces the risk of output overvoltage.
Note that although the maximum case temperature
allowed is lower than 100 °C under some conditions,
this modules derating is equivalent to or better than the
JW050A. At full load, the JW050A power module has a
higher case temperature rise than the JBW050A.
Overtemperature Protection
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).
The module features an overtemperature 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.
10
Lineage Power
LINEAGEPOWER [ LINEAGE POWER CORPORATION ]
