MQME-28E-P
Current: 20A
Technical Specification
WhenꢀusedꢀwithꢀSynQor’sꢀDC/DCꢀconverters,ꢀtheꢀMQME-28E-Pꢀ
EMIꢀfilterꢀisꢀdesignedꢀtoꢀpassꢀallꢀofꢀtheꢀrelevantꢀMIL-STD-461C/
D/Eꢀrequirementsꢀtoꢀtheirꢀmostꢀstringentꢀlimits.ꢀꢀTheꢀMIL-STD-461ꢀ
ComplianceꢀMatrixꢀTableꢀonꢀPageꢀ7ꢀlistsꢀtheseꢀrequirementsꢀandꢀ
describesꢀtheꢀsetupꢀusedꢀtoꢀpassꢀthem.ꢀꢀFiguresꢀ3ꢀ-ꢀ6ꢀshowꢀresultsꢀ
from selected conductive and radiated emissions tests.
BASICꢀOPERATIONꢀANDꢀFEATURES
TheꢀMQME-28E-Pꢀisꢀaꢀmulti-stageꢀdifferential-modeꢀandꢀcommon-
mode passive EMI filter designed to interface a power source with
one or more SynQor DC/DC converters (or other loads that create
EMI).ꢀꢀEachꢀstageꢀofꢀthisꢀfilterꢀisꢀwellꢀdampedꢀtoꢀavoidꢀresonancesꢀ
andꢀoscillations,ꢀandꢀonlyꢀX7Rꢀmulti-layerꢀceramicꢀcapacitorsꢀareꢀ
used.ꢀꢀFigureꢀ1ꢀshowsꢀtheꢀtypicalꢀdifferentialꢀandꢀcommon-modeꢀ
attenuation provided by this filter when the source impedance is
50Ω to chassis ground on each input line.
The filter is also designed to pass the waveform types and
applicationsꢀ specifiedꢀ inꢀ RTCA/DO-160Eꢀ Sectionꢀ 22ꢀ (Lightningꢀ
Inducedꢀ Transientꢀ Susceptibility)ꢀ toꢀ Levelꢀ 4ꢀ (someꢀ waveforms/
applicationsꢀ requireꢀ theꢀ MQME-28-Tꢀ filterꢀ and/orꢀ externalꢀ
transientꢀ suppressionꢀ circuitry).ꢀ ꢀ Theꢀ Sectionꢀ 22ꢀ Complianceꢀ
Matrixꢀ Tableꢀ onꢀ Pageꢀ 9ꢀ listsꢀ theseꢀ waveformsꢀ andꢀ applicationsꢀ
and describes the setup used to pass them.
TheꢀMQME-28E-PꢀEMIꢀfilterꢀincludesꢀaꢀlargeꢀbulkꢀcapacitorꢀ(alsoꢀ
X7R)ꢀwithꢀaꢀseriesꢀdampingꢀresistorꢀtoꢀcorrectꢀforꢀtheꢀunstabilizingꢀ
effect of a converter’s negative input resistance. A white paper
discussing this negative input resistance and the need for corrective
damping can be found on the SynQor website (see Input System
Instabilityꢀapplicationꢀnote).ꢀFigureꢀ2ꢀshowsꢀtheꢀmagnitudeꢀofꢀtheꢀ
filter’s output impedance when the filter input is connected to a
stiff voltage source.
A typical application would place the MilQor filter close to the
input of the DC/DC converter, with the cases of the filter and
theꢀconverterꢀconnectedꢀtogetherꢀthroughꢀaꢀgroundꢀplane.ꢀꢀBothꢀ
cases are electrically conductive, so connection to the cases can
be made with the fasteners used to secure the device.
The input voltage surge and spike compliance matrix shown on
Pageꢀ 8ꢀ displaysꢀ theꢀ worstꢀ caseꢀ requirementsꢀ listedꢀ inꢀ variousꢀ
28VꢀMilitaryꢀ(VehicleꢀandꢀAircraft)ꢀandꢀCivilꢀAircraftꢀstandards.ꢀ
Theꢀ MQME-28E-Pꢀ EMIꢀfilterꢀ isꢀ designedꢀ toꢀ handleꢀ allꢀ ofꢀ theꢀ
shortꢀ durationꢀ voltageꢀ spikeꢀ requirementsꢀ ofꢀ theseꢀ standardsꢀ
(withꢀ certainꢀ assumptionsꢀ regardingꢀ DEF-STANꢀ 61-5).ꢀ Someꢀ ofꢀ
theꢀ longꢀ durationꢀ voltageꢀ surgeꢀ requirementsꢀ remainꢀ withinꢀ theꢀ
50Vꢀ maximumꢀ transientꢀ ratingꢀ ofꢀ aꢀ SynQorꢀ MQFL-28ꢀ DC/DCꢀ
converter.ꢀTheꢀothersꢀrequireꢀtheꢀtransientꢀsuppressionꢀcircuitryꢀofꢀ
anꢀ MQME-28-Tꢀ EMIꢀfilterꢀ toꢀ protectꢀ theꢀ converterꢀ fromꢀ anꢀ over-
voltageꢀ condition.ꢀ Ifꢀ MQFL-28Eꢀ orꢀ MQFL-28VEꢀ convertersꢀ areꢀ
used,ꢀvoltageꢀsurgesꢀasꢀhighꢀasꢀ80Vꢀcanꢀbeꢀtoleratedꢀwithoutꢀtheꢀ
need for this transient suppression circuitry.
Doꢀ notꢀ connectꢀ theꢀ outputsꢀ ofꢀ multipleꢀ MQME-28E-Pꢀ filtersꢀ inꢀ
parallel. Connecting filters in this manner may result in slightly
unequalꢀcurrentsꢀtoꢀflowꢀinꢀtheꢀpositiveꢀandꢀreturnꢀpathsꢀofꢀeachꢀ
filter.ꢀ Theseꢀ unequalꢀ currentsꢀ mayꢀ causeꢀ theꢀ internalꢀ common-
mode chokes to saturate and thus cause degraded common-mode
rejection performance.
Product # MQME-28E-P
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-0005135 Rev. A
03/18/09
Page 6
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