GE Industrial Solutions JRW450U Orca Series - Manual (Page 9)

GE
Data Sheet
JRCW450U Orca Series; DC-DC Converter Power Modules
36–75 Vdc Input; 48.0Vdc Output; 450W Output
June 7, 2013 ©2012 General Electric Company. All rights reserved. Page 9
Feature Description (continued)
The voltage between the Vo(+) and Vo(-) terminals must not
exceed the minimum output overvoltage shut- down value
indicated in the Feature Specifications table. This limit
includes any increase in voltage due to remote- sense
compensation and output voltage set-point adjustment (trim).
See Figure 11.
Although the output voltage can be increased by both the
remote sense and by the trim, the maximum increase for the
output voltage is not the sum of both.
The maximum increase is the larger of either the remote
sense or the trim.
The amount of power delivered by the module is defined as
the voltage at the output terminals multiplied by the output
current. When using remote sense and trim, the output
voltage of the module can be increased, which the same
output current would increase the power output of the
module. Care should be taken to ensure that the maximum
output power of the module remains at or below the
maximum rated power.
Examples:
To trim down the output of a nominal 48V module, without –T
option, to 40V
100
48
40 48
%


 
V
V V
∆% = 16.7%
 





 
K R
down adj
2
7 . 16
100
_
R
adj _ down
= 3.99
To trim up the output of a nominal 48V module, without –T
option, to 52.8V
100
48
48 8 . 52
%


 
V
V V
∆% = 10




  


 

10
)) 10 2 ( 100 (
10 225 . 1
) 10 100 ( 48
_ up adj
R
R
adj _ up
= 429.8kΩ
Active Voltage Programming
For the JRCW450Ux a Digital-Analog converter (DAC), capable
of both sourcing and sinking current can be used to actively
set the output voltage, as shown in Figure 15. The value of R
G
will be dependent on the voltage step and range of the DAC
and the desired values for trim-up and trim-down
∆%. Please
contact your GE technical representative to obtain more
details on the selection for this resistor.
Figure 15. Circuit Configuration to Actively Adjust the
Output Voltage.
Over Temperature Protection
The JRCW450U module provides a non-latching over
temperature protection. A temperature sensor monitors the
operating temperature of the converter. If the reference
temperature, T
REF 1
, (see Figure 16) exceeds a threshold of 115
ºC (typical), the converter will shut down and disable the
output. When the base plate temperature has decreased by
approximately 1-2 ºC the converter will automatically restart.
Thermal Considerations
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 thermally coupled to the case.
Heat is removed by conduction, convection, and radiation to
the surrounding environment. Proper cooling can be verified
by measuring the case temperature.
Peak temperature (T
REF
)
occurs at the position indicated in Figure 16.
Considerations include ambient temperature, airflow, module
power dissipation, and the need for increased reliability. A
reduction in the operating temperature of the module will
result in an increase in reliability.
The thermal data presented here is based on physical
measurements taken in a wind tunnel, using automated
thermo-couple instrumentation to monitor key component
temperatures: FETs, diodes, control ICs, magnetic cores,
ceramic capacitors, opto-isolators, and module pwb
conductors, while controlling the ambient airflow rate and
temperature. For a given airflow and ambient temperature,
the module output power is increased, until one (or more) of
the components reaches its maximum derated operating
temperature, as defined in IPC-9592. This procedure is then
repeated for a different airflow or ambient temperature until a
family of module output derating curves is obtained.