F
EATURES
• –55°C to +125°C operation
• 50 dB minimum attenuation
at 500 kHz
• Compliant to MIL-STD-461C, CE03
• Compatible with MIL-STD-704E
DC power bus
EMI I
NPUT
F
ILTER
28 V
OLT
I
NPUT
FMSA EMI FILTER
0.8 AMP
MODEL
FMSA-461
0.8 amp
Size (max.): 0.980 x 0.805 x 0.270 (24.89 x 20.45 x 6.86 mm)
See cases “A maximum dimensions” and “A1” for dimensions.
Weight:
10.3 grams typical, 11.5 grams maximum
Screening: Standard, ES or Class H
See “QA Screening: Class H, QML” for more information.
DESCRIPTION
The FMSA-461 EMI filter module has been designed as a
companion for Interpoint MSA flyback power converters. Multiple
MSA power converters can be operated from a single filter provided
the total power line current does not exceed the filter maximum
rating. The FMSA filter will reduce the MSA’s power line reflected
ripple current to within the limit of MIL-STD-461C, Method CE03, as
shown in the example of Figures 4 and 5.
The FMSA is fabricated using thick film hybrid technology and is
sealed in a metal package for military, aerospace and other appli-
cations requiring EMI suppression. The filter uses only ceramic
capacitors for reliable high temperature operation.
The FMSA filter can also be used with other types of Interpoint
power converters (MHF, MHF+, MHE, MHD, and DCH series) to
comply with CE03. For MHF, MHF+, MHD, and MHE models, the
converter has an LC type line filter such that an inductor is seen
looking into its positive input terminal. For these converters, it is
necessary to terminate the filter with a capacitor to insure uncondi-
tionally stable operation. A capacitor across the filter output termi-
nals of greater than 4µF or the optional damping circuit shown on
the connection diagram will be adequate for stable operation. No
capacitor is required for MSA, or DCH models.
O
PTIONAL
D
AMPING
C
IRCUIT
The optional damping circuit (Figure 2) can be used to prevent filter
overshoot caused by MIL-STD-704A 80 V, or other, transients
having rise times of less than 200 µSec. This damping can be alter-
nately provided with a 1.50
Ω
resistor in series with the filter positive
input where the additional line loss can be tolerated. For transients
with rise times of greater than 200 µsec, there is no overshoot and
the damping circuit is not required.
O
PERATION
The MSA power converter has an internal 2 µF capacitor across its
input power terminals. When the MSA and FMSA filters are used
together, this capacitor becomes part of the filter and forms its final
LC output section. When 2 or 3 MSAs are used with a single filter,
this capacitor becomes 4 µF or 6 µF respectively, rather than 2 µF,
improving the rejection vs. frequency.
L
AYOUT
R
EQUIREMENTS
The case of the filter must be connected to the case of the converter
through a low impedance connection to minimize EMI.
INTERPOINT [ INTERPOINT CORPORATION COMPANY ]
