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EMC DesignFundamentals
James Colotti
EMC Certified by NARTEStaff Analog Design EngineerTelephonics - Command Systems Division
Outline
Introduction
Importance of EMC Problems with non-compliance
Concepts & Definitions
Standards
FCC, US Military, EU, RTCA
Design Guidelines and Methodology
EM Waves, Shielding Layout and Partitioning
Power Distribution
Power Conversion
Signal Distribution
Design Process
References and Vendors
Revision 3Copyright Telephonics 2003-2005
Introduction
Revision 3Copyright Telephonics 2003-2005
Importance of EMC
Electromagnetic Compatibility (EMC) requires th systems/equipment be able to tolerate a specifi of interference and not generate more than a sp amount of interference
EMC is becoming more important because there many more opportunities today for EMC issues
Increase use of electronic devices
Automotive applications Personal computing/entertainment/communication
Increased potential for susceptibility/emissions
Lower supply voltages Increasing clock frequencies, faster slew rates
Increasing packaging density
Demand for smaller, lighter, cheaper, lower-power
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Problems with Non-Complia
Product may be blocked from market
Practical impact can be minor annoyance to lethal and everything in between
Annoyance,Lost Revenue, MinorSignificant
DelaysProperty LossProperty Loss
AM/FM/XM/TV Critical communications RADAR,
InterferenceInterference/InterruptionSystem I
Cell PhoneAutomated MonetaryErroneou
InterferenceTransactionsFiring
Improper
of Airbag
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Non-Compliance (continue
Fortunately, industry is well regulated and standa comprehensive
Major EMC issues are relatively rare
For cost-effective compliance
- EMC considered throughout product/system developm
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Concepts&Definitions
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Concepts & Definitions
Electromagnetic Interference (EMI)
Electromagnetic emissions from a device or system th interfere with the normal operation of another device
Also referred to as Radio Frequency Interference (RFI
Electromagnetic Compatibility (EMC)
The ability of equipment or system to function satisfa its Electromagnetic Environment (EME) without introd intolerable electromagnetic disturbance to anything in environment In other words: Tolerate a specified degree of interference,
Not generate more than a specified amount of interfe Be self-compatible
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Concepts & Definitions, Contin
For an EMC problem to exist:
System/Device that generates interference System/Device that is susceptible to the interference
Coupling path
Coupling Path
System/DeviceSystem/Dev
that generatesthat is
interferencesusceptible
ConductedRadiatedInterferenc
(Culprit) Power Lines Magnetic
(Victim)
Signal Lines Electric
Mitigation of EMC Issues Plane Wave
Reduce interference levels generated by culprit Increase the susceptibility (immunity) threshold of the
Reduce the effectiveness of the coupling path
Combination of the above
Source (Culprit)Coupling PathReceiver (Victi
Modify Signal RoutingIncrease SeparationModify Signal Routi
Add Local FilteringShieldingAdd Local Filtering
Operating Freq SelectionReduce # of InterconnectionsOperating Freq Sele
Freq DitheringFilter Interconnections
Reduce Signal Level
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Standards
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Some of the Institutes tha Establish EMC Standards
Federal Communication Commission (FCC)
US Military
European Union (EU)
Radio Technical Commission for Aeronautics (RTC
This lectures main focus is on EMC Fundamentals
Electro Static Discharge (ESD) Direct Lightning Effects
Antenna Lead Conducted Emissions/Susceptibility
RF Radiation Safety
Revision 3Copyright Telephonics 2003-2005
FCC Part 15
Conducted Emissions
FrequencyQuasi-Peak LimitAverage
(MHz)(dBuV)(dBu
Class A0.15 0.57966
0.5 - 30.07360
Class B0.15 0.566 to 56 *56 to 4
0.5 55646
5 - 306050
*Decrease as logarithm of frequency
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FCC Part 15
General Radiated Emission
FrequencyField Strength Li
(MHz)(uV/m)
Class A30 8890
88 216150
(10 meters)216 960210
above 960300
Class B30 88100
88 216150
(3 meters)216 960200
above 960500
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MIL-STD-461E
Requirements for the Control of EMI Characteristics of Subsystems & E
ReqtDescription
CE101Conducted Emissions, Power Leads, 30 Hz to 10 kHz
CE102Conducted Emissions, Power Leads, 10 kHz to 10 MHz
CE106Conducted Emissions, Antenna Terminal, 10 kHz to 40 GHz
CS101Conducted Susceptibility, Power Leads, 30 Hz to 50 kHz
CS103Conducted Susceptibility, Antenna Port, Intermodulation, 15 kHz to 10 GHz
CS104Conducted Susceptibility, Antenna Port, Rejection of Undesired Signals, 30 Hz to 20 G
CS105Conducted Susceptibility, Antenna Port, Cross Modulation, 30 Hz to 20 GHz
CS109Conducted Susceptibility, Structure Current, 60 Hz to 100 kHz
CS114Conducted Susceptibility, Bulk Cable Injection, 10 kHz to 200 MHz
CS115Conducted Susceptibility, Bulk Cable Injection, Impulse Excitation
CS116Conducted Susceptibility, Dampened Sinusoidal Transients, Cables & Power Leads, 10
RE101Radiated Emissions, Magnetic Field, 30 Hz to 100 kHz
RE102Radiated Emissions, Electric Field, 10 kHz to 18 GHz
RE103Radiated Emissions, Antenna Spurious and Harmonic Outputs, 10 kHz to 40 GHz
RS101Radiated Susceptibility, Magnetic Field, 30 Hz to 100 kHz
RS103Radiated Susceptibility, Electric Field, 10 kHz to 40 GHz
RS105Radiated Susceptibility, Transient Electromagnetic Field
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EU Standard Examples (Emiss
StandardDescription
EN50081-1Generic emissions standard for residential, commercial and li
industrial environments.
EN50081-2Generic emissions standard for industrial environment
EN55022Limits and methods of measurement of radio disturbance
characteristics of information technology equipment
(Also known as CISPR-22)
EN55011Industrial, scientific and medical (ISM) radio frequency equip
Radio disturbance characteristics - Limits and methods of
measurement
(Also known as CISPR-11)
EN55013Limits and methods of measurement of radio disturbance
characteristics of broadcast receivers and associated equipme
EN55014-1Emission requirements for household appliances, electric tool
similar apparatus
EN55015Limits and methods of measurement of radio disturbance
characteristics of electrical lighting and similar equipment
EN61000-3-2Limits for harmonic current emissions (equipment input curre
and including 16 A per phase)
EN61000-3-3Limitation of voltage changes, voltage fluctuations and flicker
public low-voltage supply systems
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EU Standard Examples (Immu
StandardDescription
EN61000-4-2Electrostatic Discharge
EN61000-4-3Radiated Susceptibility Test
EN61000-4-4Electrical Fast Transient/Burst Test
EN61000-4-5Surge Test
EN61000-4-6Conducted Immunity Test
EN61000-4-8Power Frequency Magnetic Test
EN61000-4-11Voltage Dips and Interruptions Test
EN61000-6-1Immunity for residential, commercial and light-industrial
environments
EN61000-6-2Immunity for industrial environments
EN61547Equipment for general lighting purposes EMC immunity
requirements
EN12016Electromagnetic compatibility Product family standard for
escalators and passenger conveyors Immunity
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Standard Example - RTCA
DO-160, Environmental Conditions & Test Procedures fo Equipment
SectionTitleNotes
16Power Input115 VAC, 28 VDC and 14
Voltage/frequency range,
surges
17Voltage SpikePower Leads
Up to 600 V or 2x Line V
18Audio Frequency Conducted Susceptibility 0.01 - 150 kHz or 0.2 - 1
Power Inputs
19Induced Signal SusceptibilityInterconnection Cabling
E field and H Field
400 Hz 15 kHz and spik
20Radio Frequency Susceptibility (RadiatedConducted: 0.01-400 MH
and Conducted)Radiated: 0.1-2, 8 or 18
21Emission of Radio FrequencyPower Lines: 0.15-30 MH
Interconnecting Cables:
Radiated: 2-6,000 MHz
22Lightning Induced Transient SusceptibilityPin & Bulk injection, Puls
Sine
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Standard Summary
Numerous EMC standards exists
Common Fundamental Theme
Conducted Emission Limits Radiated Emission Limits
Conducted Susceptibility (Immunity) Limits
Radiated Susceptibility (Immunity) Limits
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Design GuidelinesandMethodology
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Electromagnetic Waves
Electromagnetic waves consist of two orthogonal f
Electric, E-Field (V/m) Magnetic, H-Field (A/m)
Wave Impedance, ZW=E/H
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Electromagnetic Waves
E-Fields, high impedance, wire (dipole)
H-Fields, low impedance, current loops (xformer)
In far field, all waves become plane waves
d > 2
Far Field for a Point Source
= 04 107H
ZW=m =120 = 377
19 F
0
36 10m
Impedance of Plain Wave
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Shielding
Enclosure/Chassis
Mechanical Structure Thermal Path
Can form an overall shield (important EMC componen
Can be used as first line of defense for Radiated emission/susceptibility
Some Applications Cannot Afford Overall Shield
Rely of other means of controlling EMC
Enclosure material
Metal Plastic with conductive coating (Conductive paint or vacuum deposition)
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Shielding Illustration
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Shielding Effectiveness
Shielding effectiveness (SE) is a measure of how enclosure attenuates electromagnetic fields
SEdB = 20Log10 EInsideEOutside
Theoretical SE of homogeneous material
Reflective losses, R Absorption losses, A and
Secondary reflective losses, B (ignore if A>8 dB)
SE = R + A + B SE = R + A
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SE Equations
0.462r0136.r
R h = 20Log10++ 0.354
rfrr
fr
Magnetic Field Reflective Loss
f3rr2
Re = 354 - 10 Log10r
Electric Field Reflective Loss
Rp = 168 + 10 Log
r
10r f
Plane Wave Reflective Loss
A = 0.003338t
Absorptive Los
where:t = Material thickness (mils) r = Material permeability rela r = Material conductivity rela f = Frequency (Hz)r = Source to shield distance
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SE Theoretical Examples
FreqAluminum (60 mils)Cold Rolled Steel (60 mils)Coppe
(Hz)MagneticElectricPlaneMagneticElectricPlaneMagneticEl
(dB)(dB)(dB)(dB)(dB)(dB)(dB)(
10k58>200141125>200>20045>
100k101>200165>200>200>200571
1M>200>200>200>200>200>200741
10M>200>200>200>200>200>2001061
100M>200>200>200>200>200>2001841
1G>200>200>200>200>200>200>200>
r=12
r = 1 (Aluminum), 180 (Cold Rolled Steel), 1 (Copper)
r = 0.6 (Aluminum), 0.17 (Cold Rolled Steel), 1 (Coppe
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SE Practical Consideration
SE is typically limited by apertures & seams
Removable Covers Holes for control/display components
Holes for ventilation
Holes for connectors
Mitigation of apertures and seams
Minimize size and number of apertures and seams Use gaskets/spring-fingers to seal metal-to-metal inte
Interfaces free of paint and debris
Adequate mating surface area
Avoid Galvanic Corrosion
Use of EMI/conductive control/display components
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Holes/Apertures d>t
d
t
Single HoleMulti
s
< d
If2SE 0dBdIf s < 2 >
If> dSE 20Log10SE 20Log
22d
t
where:t = Material thickness n = Number of Holess = edge to edge hole spacing
Notes:1. d is the longest dimension of the hole.
2. Maximum SE is that of a solid barrier without aperture.
Revision 3Copyright Telephonics 2003-2005
Holes/Apertures d