Technical

Specification

IQ040PFQTx30

Product # IQ040PFQTx30

Phone 1-888-567-9596

www.synqor.com

Doc.# 005-0005371 Rev. F

08/07/13

Page 4

BASIC OPERATION AND FEATURES

This module 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.

This InQor EMI filter includes a large bulk capacitor 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).

A typical application would place the InQor filter close to the input of the

dc-dc converter. The Input common-mode pin would be connected to the

chassis ground that is common with the system input line filter or other

earthed point used for EMI measurement. The output common-mode pin

would be connected to the output ground or plane of the power convectors

with as low inductance a path as possible. There are no connections to

the metal baseplate, which may also be connected to the chassis ground

if desired.

Do not connect the outputs of multiple InQor 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.

-240

-200

-160

-120

-80

-40

0

40

1.00E+04

1.00E+05

1.00E+06

1.00E+07

1.00E+08

Frequency (Hz)

Differential Attenuation

Common-mode Attenuation

Figure 1: Typical Common Mode and Differential Mode Attenuation provided

by the filter as a function of frequency. both input lines are connected to chassis

ground through 50Ω resistors.

Basic Operations and Features