Crane Aerospace & Electronics Power Solutions
sFcs28-461 eMi input Filters
28 Volt input – 5 aMp
Features
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Fully qualified to Class H or K
Passive components used for maximum tolerance
in space environments
-55°C to +125°C operation
Nominal 28 V input, 0 V to 50 V operation
Up to 5 A throughput current
70 dB attenuation typical at 500KHz
Compliant to MIL-STD-461C CE-03
Compatible with MIL-STD-704 A-E 28 VDC power bus
I
nput
V
oltage
and
C
urrent
Model
SFCS28-461
Current (A)
5
description
The SFCS-461
TM
Series EMI Filter modules are specifically
designed to reduce the reflected input ripple current of high
frequency DC/DC converters. SFCS28-461 filters minimize elec-
tromagnetic interference (EMI) for Interpoint’s space application
converters. These filters are intended for use in 28 volt applica-
tions which must meet MIL-STD-461 levels of conducted emis-
sions. One filter can be used with multiple converters up to the
rated throughput current of the filter.
Common mode noise occurs across stray capacitance between
the converter’s power train components and the baseplate
(bottom of the package) of the converter.
Where low noise currents are required to meet CE03 of MIL-
STD-461C, a power line filter is needed. The SFCS28-461 Series
of EMI power line filters reduces the common mode and differ-
ential noise generated by the converters. SFCS28-461 filters
reduce input ripple current by at least 60 dB at 500 kHz, 1 MHz,
and 5 MHz when used in conjunction with Interpoint’s DC/DC
converters. The filter must be placed as close as possible to the
converter for optimum performance. the baseplates of the filter
and the converter should be connected with the shortest and
widest possible conductors. For the best connection, mount the
filter’s and converter’s baseplates on or above a small ground
plane.
S
creening
The SFCS28-461 filter offers three screening options - Space
Prototype (O), Class H, or Class K. Radiation tolerant to
Radiation Hardness Assurance (RHA) levels of “-” (O) or “H”,
per MIL-STD-38534. Interpoint model numbers use an “O” in
the RHA designator position to indicate the “-” (dash) Radiation
Hardness Assurance level of MIL-PRF-38534, which is defined
as “no RHA”. See “Class H and K, MIL-PRF-38534 Screening”
tables for more information.
O
peratiOn and
t
eMperature
i
nput
r
ipple and
eMi
Switching DC/DC converters naturally generate two noise
components on the power input line: differential noise and
common mode noise. Input ripple current refers to both of these
components.
Differential noise occurs between the positive input and input
common. Most Interpoint converters have an input filter that
reduces differential noise which is sufficient for most applications.
All SFCS28-461 Series filters are rated for full power opera-
tion from -55˚C to +125˚C case temperature. Current is derated
linearly to zero at +135˚C case temperature.
i
nSertiOn
l
OSS
p
ackaging
The maximum DC insertion loss at full load and nominal input
voltage represents a power loss of less than 4%.
SFCS28-461 filters are sealed in metal hermetic side-leaded
packages. For more information contact your Interpoint represen-
tative.
Crane Aerospace & Electronics
Electronics Group (Interpoint Brand)
PO Box 97005 • Redmond WA 98073-9705
425.882.3100 • electronics@craneae.com
www.craneae.com
Page 1 of 9
Rev B - 20070404
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