Data Sheet
September 6, 2008
FNW700R Power Modules; DC-DC Converters
36 – 75 Vdc Input; 28Vdc Output; 700W Output
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 470μF 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.
Test Configurations
Output Capacitance
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 7. Input Reflected Ripple Current Test Setup.
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
O
ambient temperature is under -20 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.
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 8. Output Ripple and Noise 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.
Figure 9. Output Voltage and Efficiency Test Setup.
LINEAGE
POWER
6
LINEAGEPOWER [ LINEAGE POWER CORPORATION ]
