GE
Data Sheet
FNW700R Power Modules; DC-DC Converters
36 – 75 Vdc Input; 28Vdc Output; 700W Output
October 1, 2015 ©2012 General Electric Company. All rights reserved. Page 6
Test Configurations
Figure 7. Input Reflected Ripple Current Test Setup.
Note: Measure the input reflected-ripple current with a simulated
source inductance (LTEST) of 12 µH. Capacitor CS offsets possible
battery impedance. Measure the current, as shown above.
Figure 8. Output Ripple and Noise Test Setup.
Note: Use a C
out
(470 µF Low ESR aluminum or tantalum capacitor
typical), a 0.1 µF ceramic capacitor and a 10 µF ceramic
capacitor, and Scope measurement should be made using a BNC
socket. Position the load between 51 mm and 76 mm (2 in. and 3
in.) from the module.
Figure 9. Output Voltage and Efficiency Test Setup.
Note: All measurements are taken at the module terminals. When
socketing, place Kelvin connections at module terminals to avoid
measurement errors due to socket contact resistance.
Design Considerations
Input Source Impedance
The power module should be connected to a low
ac-impedance source. Highly inductive source impedance
can affect the stability of the power module. For the test
configuration in Figure 7, a 470F Low ESR aluminum
capacitor, C
IN
, mounted close to the power module helps
ensure the stability of the unit. Consult the factory for
further application guidelines.
Output Capacitance
The FNW700R power module requires a minimum output
capacitance of 470µF Low ESR aluminum capacitor, C
out
to
ensure stable operation over the full range of load and line
conditions, see Figure 8. If the ambient temperature is
under -20
O
C, it is required to use at least 3 of the
minimum capacitors in parallel. In general, the process of
determining the acceptable values of output capacitance
and ESR is complex and is load-dependant.
Safety Considerations
For safety-agency approval of the system in which the
power module is used, the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standard, i.e.,
UL60950-1, CSA C22.2 No. 60950-1-03, EN60950-1 and
VDE 0805:2001-12.
For end products connected to –48V
dc
, or –60V
dc
nominal
DC MAINS (i.e. central office dc battery plant), no further
fault testing is required. *Note: -60V
dc
nominal battery
plants are not available in the U.S. or Canada.
For all input voltages, other than DC MAINS, where the
input voltage is less than 60V
dc
, if the input meets all of the
requirements for SELV, then:
The output may be considered SELV. Output voltages
will remain within SELV limits even with internally-
generated non-SELV voltages. Single component
failure and fault tests were performed in the power
converters.
One pole of the input and one pole of the output are
to be grounded, or both circuits are to be kept
floating, to maintain the output voltage to ground
voltage within ELV or SELV limits. However, SELV will
not be maintained if V
I
(+) and V
O
(+) are grounded
simultaneously.
