EMC design (module 1)

Goals

formation-objectifs-seointro EMC design (module 1) :

- Take all key EMC parameters into account when designing equipment

The aim of this training course is to:
- Learn how to identify and solve potential problems in analogue, digital and switching circuits
- Be able to analyse and master coupling mechanisms
- Be able to design and implement conduction and radiation remedies
- Be able to understand requirements and implement shielding solutions

Program

1/ Introduction

EMC analysis method

Common mode and differential mode

Use of decibels

Time-frequency conversion

2/ EMC regulations and tests

European directive

Harmonised standards

DO160 / MIL STD

Conducted and radiated emissions

Conducted and radiated immunity radiated immunity

EMC qualification plan

3/ EMC of active components

Signal-to-noise ratio

Bandwidth and sweep speed

Impedance and output current

Envelope detection

Static and dynamic noise margin

Waveform and equivalent frequency

Transition power consumption

4/ Switching circuits

MD and MC of a switching power supply

Common mode calculation and filtering

Differential mode calculation and filtering

Common mode input to output

5/ Common impedance coupling

Principle of common impedance coupling

Impedance of a copper plane

Impedance of tracks and wires

Star power supply

Analogue/digital comparison

Ground and power planes

Optimal solution for CIP layers

6/ Board-to-chassis coupling

Capacitive board-to-chassis coupling

Capacitance between board and ground

Capacitance of a track

Electrostatic screen and guard ring

Example of layout

Mechanical ground / electrical ground

Connection of 0 V to the chassis

7/ Coupling via crosstalk

Linear capacitance between tracks and between wires

Wire-to-wire inductive coupling

Example of track-to-track crosstalk

Crosstalk in flat cables

Crosstalk reduction using a ground plane

8/ Field-loop coupling Calculation of loop voltage Example of susceptibility Magnetic field case Twisting of conductors Field-to-wire coupling

Whip and dipole antennas

Calculation of induced current

Field reduction by ground plane

10/ Differential mode radiation

Spectrum of a trapezoidal traindal

Radiation from a small loop

Example of radiation from a clock

Reduction of loop areas

Reduction of MD radiation

11/ Common mode radiation

Radiation of a small whip

Origins of common mode current

Spectrum radiated in common mode

Warning before radiation measurement

Reduction of CM radiation

12/ Conduction protection

Methods of low-frequency protection

Asymmetrical or differential connections

Galvanic isolation Spark gaps, varistors, transzorb

Methods of high-frequency protection>Choosing a filter structure

The three rules for installing mains filters

Filtering low-level inputs

Ferrite cores, choosing the number of turns

13/ Shielded cables

Shielded and coaxial cables

Transfer impedance

Reduction effect of a shielded pair

Or connecting a shielded cable

Implementation of shielded cables

14/ Shielding

Near field / far field

Reflection and absorption losses

Shielding effectiveness

Choice of shielding material

Necessity of openings

Opening in a shield

Electrochemical couples

Conductive seals and spring fingers

Plastic metallisation

15/ Design review

EMC support for a project

Mastery of initial choices

EMC reviews