MQME-270-P
Current:
2A
Technical Specification
The MQME-270-P is a multi-stage differential-mode and common-
mode passive EMI filter designed to interface a power source with
one or more SynQor DC/DC converters (or other loads that create
EMI). Each stage of this filter is well damped to avoid resonances
and oscillations, and only X7R multi-layer ceramic capacitors are
used. Figure 1 shows the typical differential and common-mode
attenuation provided by this filter when the source impedance is
50Ω
to chassis ground on each input line.
BASIC OPERATION AND FEATURES
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Product # MQME-270-P
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-2ME027P Rev. 2
03/16/09
When used with SynQor’s DC/DC converters, the MQME-270-P
EMI filter is designed to pass all of the relevant MIL-STD-461C/D/E
requirements to their most stringent limits. The MIL-STD-461
Compliance Matrix Table on Page 7 lists these requirements and
describes the setup used to pass them. Figures 3 - 6 show results
from selected conductive and radiated emissions tests.
The filter is also designed to pass the waveform types and
applications specified in RTCA/DO-160E Section 22 (Lightning
The MQME-270-P EMI filter includes a large bulk capacitor (also Induced Transient Susceptibility) to Level 4 (some waveforms/
X7R) with a series damping resistor to correct for the unstabilizing applications require the MQME-270-T filter and/or external
effect of a converter’s negative input resistance. A white paper
transient suppression circuitry). The Section 22 Compliance Matrix
discussing this negative input resistance and the need for corrective
Table on Page 9 lists these waveforms and applications and
damping can be found on the SynQor website (see Input System describes the setup used to pass them.
Instability application note). Figure 2 shows the magnitude of the
filter’s output impedance when the filter input is connected to a stiff A typical application would place the MQME filter close to the
input of the DC/DC converter, with the cases of the filter and the
voltage source.
converter connected together through a ground plane. Both cases
The input voltage surge and spike compliance matrix shown on are electrically conductive, so connection to the cases can be made
Page 8 displays the worst case requirements listed in various
with the fasteners used to secure the device.
270V Military (Vehicle and Aircraft) and Civil Aircraft standards.
The MQME-270-P EMI filter is designed to handle all of the short Do not connect the outputs of multiple MQME-270-P filters in
duration voltage spike requirements of these standards (with certain
parallel. Connecting filters in this manner may result in slightly
assumptions regarding DEF-STAN 61-5). Some of the long duration unequal currents to flow in the positive and return paths of each
voltage surge requirements remain within the 50V maximum filter. These unequal currents may cause the internal common-
transient rating of a SynQor MQFL-270 DC/DC converter. The
mode chokes to saturate and thus cause degraded common-mode
others require the transient suppression circuitry of an MQME-270-T
rejection performance.
EMI filter to protect the converter from an over-voltage condition. If
MQFL-270E or MQFL-270VE converters are used, voltage surges
as high as 80V can be tolerated without the need for this transient
suppression circuitry.
Page 6
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