MQME-270L-P Datasheet, PDF (6/13 Pages) –

Technical Specification
MQME-270L-P
Current: 3A
BASIC OPERATION AND FEATURES
The MQME-270L-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 50W to chassis ground on each input line.
The MQME-270L-P EMI filter includes a large bulk capacitor (also X7R)
with a series damping resistor to correct for the unstabilizing 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 Instability
application note). Figure 2 shows the magnitude of the filter’s output
impedance when the filter input is connected to a stiff voltage source.
When used with SynQor’s DC/DC converters, the MQME-
270L-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 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/F/G Section 22 (Lightning
Induced Transient Susceptibility) to Level 4 (some waveforms /
applications require external transient suppression circuitry).
The Section 22 Compliance Matrix Table lists these waveforms
and applications and describes the setup used to pass them.
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 converter connected together through a ground plane. Both
cases are electrically conductive, so connection to the cases
can be made with the fasteners used to secure the device.
Do not connect the outputs of multiple MQME-270L-P filters in parallel.
Connecting filters in this manner may result in slightly unequal currents
to flow in the positive and return paths of each filter. These unequal
currents may cause the internal common-mode chokes to saturate
and thus cause degraded common-mode rejection performance.
Product # MQME-270L-P
Phone [phone]
www.synqor.com
Doc.# 005-0006389 Rev. 2
08/28/2013
Page 6