FMSA-461

FEATURES • –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 INPUT FILTER 28 VOLT INPUT 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 applications 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 unconditionally stable operation. A capacitor across the filter output terminals 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. OPTIONAL DAMPING CIRCUIT 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 alternately 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. 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. LAYOUT REQUIREMENTS 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 ABSOLUTE MAXIMUM RATINGS Input Voltage • 0 to 50 VDC continuous • 80 V for 100 ms transient Lead Soldering Temperature (10 sec per lead) • 300°C Storage Temperature Range (Case) • –65°C to +150°C EMI INPUT FILTERS RECOMMENDED OPERATING CONDITIONS Input Voltage Range • 16 to 40 VDC continuous Case Operating Temperature (Tc) • –55°C to +125°C full power Derating Input/Output Current • Derate linearly from 100% at 100°C to 0.60 amps at 125°C case. Above 125°C derate to 0%. TYPICAL CHARACTERISTICS Capacitance • 0.045 µF max, any pin to case Isolation • 100 megohm minimum at 500 V • Any pin to case, except case pin Electrical Characteristics: 25°C Tc, nominal Vin, unless otherwise specified. PARAMETER INPUT VOLTAGE INPUT CURRENT1 NOISE REJECTION NOISE REJECTION DC RESISTANCE (RDC) OUTPUT VOLTAGE OUTPUT CURRENT INTERNAL POWER DISSIPATION CONDITIONS CONTINUOUS TRANSIENT1, 100 ms 500 kHz 1 MHz 5 MHz TC = 25°C STEADY STATE STEADY STATE (285 H 6H 6H Positive Output x2 0.014 F / 500 V 2F 20 Input Common 6800 pF 500 V 2F x2 0.014 F / 500 V Output Common 0.014 F / 500 V FMSA-461 The case ground connection between the filter and the converter should be as low an impedance as possible to minimize EMI. Direct contact of baseplate to chassis ground provides the lowest impedance. FIGURE 1: SCHEMATIC – TYPICAL VALUES EMI INPUT FILTERS FMSA-461 Positive Input Positive Output C Case Ground Input Common Output Common R Case Ground Input Common Output Common DC/DC Converter Positive Input Positive Output FMSA EMI FILTER 0.8 AMP RL The RC output is an optional damping circuit. It is recommended in applications where 80 volt line transients may occur with rise times