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 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.

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.

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.

The case of the filter must be connected to the case of the converter

through a low impedance connection to minimize EMI.

FMSA EMI FILTER

0.8 AMP

• –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

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.

MODEL

FMSA-461

0.8 amp