MODELS
INPUT VOLTAGE
AND CURRENT
B3-7
Input (V)
28
28
270
270
Current ( A)
7.0
15.0
0.7
1.5
DESCRIPTION
The FMD Series™ and FME Series™ EMI filters are specifically
designed to reduce the reflected input ripple current of Interpoint’s
high frequency DC/DC converters. FMD/FME filters minimize elec-
tromagnetic interference (EMI) for the MHE, MHL, MLP, MRH, MTO,
MHF, MHF+, MHV, MHD, MTR, MFL, MHP, and MFLHP Series.
These filters are intended for use in 28 or 270 volt applications
which must meet MIL-STD-461C, CE03 levels of conducted emis-
sions. One filter can be used with multiple converters up to the rated
output current of the filter.
INPUT RIPPLE AND EMI
Switching DC/DC converters naturally generate two noise compo-
nents 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 many applications. Common
mode noise occurs across stray capacitances 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-
461, a power line filter is needed. The FMD/FME Series of EMI
power line filters reduces the common mode and differential noise
generated by the converters. FMD/FME-461 filters reduce input
ripple current by as much as 60 dB at 500 kHz and 55 dB at 1 MHz
when used in conjunction with Interpoint’s DC/DC converters. See
Figures 8 and 9.
Place the filter 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. See Figure 5.
TRANSIENTS
The transients listed below will not damage the filter but will be
passed on to the converter:
• All filters: ±600 volts (50 ohm source
impedance) for up to 10 µs.
• 28 volt filter: ±100 volts (0.5 ohm source
impedance) for up to 100 ms.
• 270 volt filter: ±500 volts (independent of
source impedance) for up to 100 ms.
OPERATION OVER TEMPERATURE
All FMD/FME-461 Series filters are rated for full power operation
from –55°C to +125°C case temperature. Current is derated linearly
to zero at +135°C case temperature.
INSERTION LOSS
The maximum dc insertion loss at full load and nominal input voltage
represents a power loss of less than 4%.
PACKAGING
FMD/FME-461 filters are sealed in metal hermetic side-leaded
packages. See Section B8, cases U1, U2, V, W, Y, and Z.
Additionally the FMD28-461 filter is available in a metal hermetic
down-leaded package (see Section B8, case J4).
LAYOUT REQUIREMENTS
The case of the filter must be connected to the case of the converter
through a low impedance connection to minimize EMI.
EMI I
NPUT
F
ILTERS
28 & 270 V
OLT
I
NPUT
FMD/FME EMI FILTER
0.7 T O 15 AMP
FEATURES
• –55°C to +125°C operation
• Up to 60 dB attenuation
at 500 kHz.
• Compliant to
MIL-STD-461C, CE03
• Compatible with
MIL-STD-704E
DC power bus
Size (max.): Case U2, FME all models; Case U1, FMD28-461SL and FMD270-461SL
3.005 x 1.505 x 0.400 inches (76.33 x 38.23 x 11.16 mm)
[FME models, shown in Case U2 (flanged, short leads). Also available:
Flanged – leads bent down (case V); Tabbed – leads bent up (case W), short
leads (case Y), and leads bent down (case Z).See Section B8, cases U2, V, W,
Y, and Z for dimensions and options.]
Case J4, FMD28-461
2.720 x 1.350 x 0.505 inches (69.09 x 34.29 x 12.83 mm)
See Section B8, cases J4, U1, U2, V, W, Y, and Z for dimensions.
Weight: 77 grams typical cases U1, U2, V, W, Y, and Z; 55 grams typical case J4
Screening: Standard, ES, or 883 (Class H).
See Section C2 for screening options, see Section A5 for ordering information.