EMC Part3 Measurement Methods Oct12

EMC measurements of components

*SummaryEMC problem examplesEM disturbance sourcesEMC certification ?EMC measurement for electronic systemsEMC measurement for integrated circuits

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*EMC problem examplesA typical electromagnetic environment*

*http://www.emcs.org/acstrial/newsletters/fall04/63_67.pdfEMC problem examplesElectromagnetic interference issues in medical devicesMedical device EMI problems reported by FDA between 1979 and 1993

405 suspected EMI problems reported by FDA between 1994 and 2005, with 6 deaths, 170 injuries and 167 malfunctions. 72 % of cases concern implantable devices.

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EMI typesReported casesDevicesConducted interference20 (1 death)Cardiac monitor, infusion device, defibrilatorRadiated interference55 (4 deaths)Pacemaker, ventilator, cardiac monitorLF magnetic field6 (1 death)Respirator, pacemakerESD10Respirator, infusion pump

*Electromagnetic interference issues in military systems29th July 1967 : accident of the American aircraft carrier USS Forrestal. The accidental launching of a rocket blew gas tank and weapon stocks, killing 135 persons and causing damages which needed 7 month reparations. Investigations showed that a radar induced on plane wiring a sufficient parasitic voltage to trigger the launching of the rocket.H.M.S. Sheffield catastrophe: During the Falklands War, the British Ship H.M.S Sheffield sank after being hit by an Exocet missile. Despite the Sheffield having the most sophisticated antimissile defense system available, the system created EMI to radiocommunications to and among the contingent of Harrier jets assigned to the ship. While the Harriers took off, the missile defense was disengaged to allow communications with the jets and provided a window of opportunity for the Exocet missile. EMC problem examples*

*Electromagnetic interference issues in automotiveInterference Technology October 2011Mercedez-Benz case: During the early years of ABS, Mercedez-Benz automobiles equipped with ABS had severe braking problems along a certain stretch of the German autobahn. The brakes were affected by a near-by-near radio transmitter as drivers applied them on the curved section of highway. The near-term solution was to a erect a mesh screen along the roadway to attenuate the EMI. This enabled the brakes to function properly when drivers applied them. Eventually, automobile ABS was qualified by EMI testing prior to procurement.EMC problem examples*

*Electromagnetic interference issues in aviation Disturbances of flight instruments causing trajectory deviations appear when one or several passengers switch on electronic devices. (Air et Cosmos, April 1993)FAA Aviation Safety Reporting System has reported 12 cases of interference in aircraft due to personal electronic devices since 2002. NASA publication 1374 (1986 1995)EMC problem examples*

*Electromagnetic interference issues in space aircraftVacuum cleaner incident: During a Spacelab mission in 1985, the crew decided to use the middeck vacuum cleaner instead of the one in the lab. Switching the middeck vacuum on caused the voltage to drop and the Remote Acquisition Unit to shut off. In preflight EMI tests, the vacuum cleaner had not been tested and should not have been used in the lab. This case shows how careful and attentive one must when dealing with EMC. [Nasa Publication 1374]EMC problem examples*

*Various disturbance sources that can affect electronic system operationNatural sourcesHuman activityIntentional emissionNon intentional emission

Electrostatic dischargeEM disturbance sources

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*Interferences from telecommunication systemsNarrowband emission, modulated signals.Regulation and planification of radioelectric spectrum controlled by ITU-R at international level, and by Agence Nationale des Frquences (ANFR) at French level.

Radio-navigationEM disturbance sources*

*Interferences from electronic systemsParasitic noise generated by the activity (switching) of any electrical or electronic devicesThe noiise is usually impulse type broadband noise.Example : Radiated emission from a 16 bit microcontroller

EM disturbance sources*

*The EM environment according to ITU-R 372-8Ambient field levels defined from EM survey in 70s.Recent surveys show a 20 40 dB increase in semi-enclosed environment.Example: Survey of the average level of electric field in Canada during the 90s in urban and suburban environment: between 1 and 20 V/m.

EM disturbance sources*

*The EM environmentEM disturbance sourcesSite Agence Nationale des Frquences (www.anfr.fr) outil Cartoradio.

Champ EEtot = 4.35 V/mDistance antenne point de mesure = 60m*

*EM disturbances can induce major failures in electronic systems.The parasitic emission and susceptibility to EM disturbances must be tested to ensure electromagnetic compatibility of an electronic systems within a nominal environment.

SummaryBut it is a tedious task because:Diversity in terms of electronic devicesNumerous types of disturbances (LF, HF, pulsed, modulated), numerous EM environmentVarious EM coupling possibilities (conducted, radiated, near-field)

How defining generic tests to guarantee EMC for any electronic systems in any EM environment, with an industrial realism ?

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*The EMC certificationThe European directive 89/336/EEC (1996) and then 2004/108/EC (2004) requires that all electrical apparatus placed on the European market :Do not produce electromagnetic interferences able to disturb radio or telecom equipments , and the normal operation of all equipmentsHave a sufficient immunity level to electromagnetic interferences to prevent any degradation of the normal operation.

All manufacturers of electrical apparatus must certify that the directive is supposed respected by delivering a declaration of conformity and placing a CE mark on the product.

Using harmonized standards adapted to the product to verify the supposition of conformity is recommended

EMC European Directive*

*The EMC certificationR&TTE European DirectiveThe European directive 99/5/EC (1999) Radio & Telecommunications Terminal Equipment which is applied to all telecom and radio equipments emitting on the band 9 KHz 3000 GHz replace the EMC directive. . R&TTE requires that telecom and radio equipments placed on the European market: :Comply to safety constraints given by the Low Voltage directive (73/23/EEC) (e.g. the limit of EM exposure for persons) and the EMC constraints given by the EMC directive 2004/108/EC.Radio equipments use spectral resources dedicated for terrestrial and spatial communications without generating any interferences.R&TTE mark:

Required for all equipments under the R&TTE directive

Warning signal for class 2 equipments (special recommandations)*

*InternationalEuropeanInternational Electrotechnical Commission(IEC)TC77Comit International Spcial des Perturbations Radiolectriques(CISPR)IEC 61000-XCISPR-XXEuropean Commitee for Electrotechnical Standardization (CENELEC)European Telecommunication Standards Institute (ETSI)EN 300XXEN 50XXXEN 55XXXEN 6XXXX

Harmonized standardsThe EMC certificationEMC normative bodies: the importance of EMC standards !*

Commercial harmonized standard (non exhaustive list !)The EMC certification**

Basic standard(general and fundamental rules)EN 61000-4-x(IEC61000-4-x)EMC Testing and measurement techniquesGeneric standard(for equipments in a specific environment)EN 61000-6-3 (IEC61000-6-3)Generic Emission Standard, for residential, commercial and light industrial environmentEN 61000-6-1 (IEC61000-6-1)Generic Immunity Standard, for residential, commercial and industrial environmentProduct standard(for a specific product family)EN 55022(CISPR22)Information technology equipment (ITE)EN 55014(CISPR14)Household appliances, electric tools and similar apparatusEN 55012(CISPR12)Vehicles, boats and internal combustion enginesEN 330220 (ETSI 330 220)Electromagnetic compatibility and radio spectrum matters (ERM); Short Range Devices (SRD); Radio equipment to be used in the 25 MHz to 1 000 MHz frequency range with power levels ranging up to 500 mW;EN 330330(ETSI 300330-1) Electromagnetic compatibility and radio spectrum matters (ERM); Short Range devices (SRD); Radio equipment to be used in the frequency range 9 KHz to 25 MHz and inductive loop systems in the frequency range 9 KHz to 30 MHz

*Automotive, military, aerospace and railway industries have developed their own EMC standards.

Commercial harmonized standard (non exhaustive list !)The EMC certification*

ApplicationsStandard referencesAutomotiveISO 7637, ISO 11452, CISPR 25, SAE J1113AerospaceDO-160, ED-14MilitaryMIL-STD-461D, MIL-STD-462D, MIL-STD-461ERailwayEN 50121

*Case study 1The EMC certificationYou want to place on the European market a ventilator for domestic installation. It is supplied by mains (220 V).

Which EMC standard(s) should you follow ? What tests should you conduct for the EMC certification ?

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Application of EN55014-1 and 2: Electromagnetic compatibility Requirements for household appliances, electric tools and similar apparatus Part 1 = Emission, Part 2 = Immunity :Any domestic electric/electronic equipments, toys, electric tool supplied under 250 V (monophase) (motors, heat elements, thermostats )Except light modules (EN55015), radio receivers (EN55025), gaming machine (EN55022).

The EMC certification*Case study 1*

*Case study 2The EMC certificationSuggested emission tests:

Suggested immunity tests:

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Conducted emission150 KHz 30 / 300 MHzHarmonic and flickerRadiated emission30 MHz 1 GHz

ESD4 KV contact / 8 KV airEFT / burst5/50 ns, 1 KV, 5 KHz repetitionConducted immunity150 KHz 230 MHz, 3 V rmsRadiated immunity80 1000 MHz, 3 V/m, modulation AM 1 KHz 80%Surge1 KV 1.2/50 s pulse on powerVoltage dips and interruptions40 % variations of the power supply, repeated 5

*The EMC certificationYou want to place on the European market a radio emitter/receiver for remote control application in residential environment. The radio emitter use the ISM band around 434 MHz. Its maximum radiated power is limited to 500 mW. The emitter/receiver is an handheld device.


Case study 2*

*Case study 2The EMC certificationThe harmonized standard EN 300220: Electromagnetic compatibility and radio spectrum matters (ERM); Short Range devices (SRD); Radio equipment to be used in the 25 MHz to 1000 MHz frequency range with power levels ranging up to 500 mW is adapted to short range devices :either with a Radio Frequency (RF) output connection and/or with an integral antenna;for alarms, identification, telecommand, telemetry, etc., applications;with or without speech.It covers fixed stations, mobile stations and portable stations, all types of modulation.

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*Case study 2The EMC certificationList of suggested tests:

Some ESD tests should be also done

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Frequency error or driftDoes the carrier frequency remains stable?Effective radiated powerThe radiated power must not exceed a max. level (< 500 mW)Transient powerThe switching of the transmitter produces interferences in adjacent spectrumAdjacent channel powerThe power transmitted in adjacent band must be limited.Spurious emissionsParasitic emissions from the emitter and receiver between 9 KHz and ?? Must be limited.Frequency stability under low voltage conditionsThe emission from the transmitter must remain stable even in extreme low power conditions.Duty cycleThe manufacturer must indicate the duty cycle of the equipmentBlocking or desensitizationCapability of the receiver to receive a wanted signal in presence of unwanted signal

*Case study 3The EMC certificationYou are a semiconductor manufacturers and you want to sell your integrated circuits in the European market. Your ICs are dedicated to automotive applications.


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*Case study 3The EMC certificationIf your integrated circuits can not operate by themselves, you dont need EMC certification.However, your customers will certainly push you to guarantee the low emission and susceptibility of your devices, require measurements, models, support.Examples of standards providing EMC measurement for ICs:IEC 61967: Integrated Circuits, Measurement of Electromagnetic Emissions, 150 kHz to 1 GHzIEC 62132: Integrated circuits - Measurement of electromagnetic immunity, 150 kHz to 1 GHzISO11452: Road vehicles - Electrical disturbances by narrowband electromagnetic energy - Component test methodsISO 7637 or IEC61000-4-2/4/5 for ESD, pulse, surge testing.

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*Why EMC standard measurement methodsCheck EMC compliance of ICs, equipments and systemsComparison of EMC performances between different products, different technologies, designs, PCB routingsImprove interaction between customers and providers (same protocols, same set-up)

EMC measurement for electronic systems*

*EMC measurement for electronic systemsEquipment / Device under testEmission measurements General measurement set-up*

*EMC measurement for electronic systemsEmission measurements Emission spectrumAmplitude (dBV)Frequency (MHz)*

*EMC measurement for electronic systemsEmblematic EMC equipment Spectrum Analyzer (EMI receiver)Frequency adjustment : Start, stop , centerAmplitude adjustment : Level reference, dynamic.Emission measurement requires high sensitivity and resolutionEmission measurement standards often recommend spectrum analyzer adjustment

RBW frequency resolution, noise floor reductionVBW smooth display50 Ohm inputX= frequencyY= power (dBm, dBV)*

*EMC measurement for electronic systemsEmblematic EMC equipment Spectrum Analyzer (EMI receiver)

Principle: based on super heterodyne receiver

INfFrfLOfFloInput signalLocal oscillatorOutput signalMixerIF filterP = .A+No.RBW

Detected power:*

*AttenuatorDC blockingLow pass filterIF filterAnalog filterGain logVideo filterMixersLocal oscillatorReference oscillatorFrequency sweepDisplayEnvelope detectorBuilding blocks and adjustable elements:

Input signalRBWVBW

DetectorAttenuation

Fstart / FstopFcenter / SpanPoint numberEMC measurement for electronic systemsEmblematic EMC equipment Spectrum Analyzer (EMI receiver)*

*Example: effect of RBW and VBW.Measurement of 100 MHz sinus.

Amplitude = 90 dBVAmplitude = 20 dBVSweep time :RBW = 100 KHz 2.5 msRBW = 10 KHz 100 msSweep time :VBW = 30 KHz 100 msVBW = 1 KHz 980 msEMC measurement for electronic systemsEmblematic EMC equipment Spectrum Analyzer (EMI receiver)*

*Example: Influence of detector type (peak vs. quasi-peak vs. average).Measurement of radiated emission of a microcontroller.

EMC measurement for electronic systemsEmblematic EMC equipment Spectrum Analyzer (EMI receiver)*

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Device under testWide band (calibrated) antenna

Power supply, DUT controlEMI receiver or spectrum analyzer)

AbsorbentsR = 3 ou 10 m1 m1 m1 mFaraday cage (with absorbents: semi-anechoic chamber)(Siepel)EN55022EMC measurement for electronic systemsRadiated emission in (semi-)Anechoic chamber (30 MHz 1 GHz)*

EMC measurement for electronic systemsE field

EMI receiver50 Optional pre-amplifierLow loss 50 cableBilog antenna(or log-periodic, biconical, dipole)VemiRadiated emission in (semi-)Anechoic chamber (30 MHz 1 GHz)If far field and free space conditions ensured:AF = Antenna factor (from calibration)The E field varies in 1/r with the distance r (the radiated power in 1/r) possible extrapolation of field intensity. **

EMC measurement for electronic systemsRadiated emission in (semi-)Anechoic chamber (30 MHz 1 GHz)Lets consider a radio receiver (such as a mobile phone). We suppose that it operates at 900 MHz, its antenna has an antenna factor of 29 dB/m, and its receiving floor is -90 dBm. It is placed at 1 m of a noisy electronic equipment with a CE Mark.Could you have a risk of interferences ?**

The noisy equipment with CE mark has certainly passed a radiated emission test in anechoic chamber, so its emission level is certainly less than a given electric field at 900 MHz. We should know the standard followed during the EMC test to deduce the radiated field. An interference can arise if this noisy equipment placed close to the receiver produces an E field larger than the receiving limit of the receiver. Lets compute the minimum E field that the receiver can detect: the noise floor is given in power on 50 ohms lets compute a voltage :V (dBV) = P (dBm) + 90 + 10log R = P (dBm) + 107 (if R = 50 ohms) Pnoise = -90 dBm Vnoise = 17 dBV. As the antenna of the receiver has an antenna factor AF = 29 dB/m > the min E field that the receiver can detect is equal to: Enoise = Vnoise + AF = 17+29 = 46 dBV/m.The graph gives the radiated emission limit at 1 m from 3 different standards (class corresponds to different level of severity of the standard):

> CISPR22: this product standard is dedicated to ITE (information technology equipment). The level given by this standard are larger than the noise floor of our radio receiver, so an interference can arise. This standard certainly dont consider the possibility of the presence of a radio receiver at proximity of the ITE equipment. Placed at 3 m, the E field is reduced by 3 - 9dB, so the interference risk is reduced.

> CISPR 25 : this product standards concerned any components or electronic modules placed on board of a vehicle and is dedicated to protection of radio receivers. The max. limit for the radiated emission is between 25 and 49 dBV/m at 1 m depending on the severity class, our receiver is protected at 1 m of our equipment.

> MIL-STD-461E: this is a military standard. The max. level is between 44 and 64 dBV/m possibility of interferences.

*Equipment / Device under testEMC measurement for electronic systemsImmunity measurements General measurement set-up*

*EMC measurement for electronic systemsImmunity measurements General test procedure for harmonic disturbanceF = FminP = PminIncrease PWait dwell timeFailure or P = Pmax ?

Save F and PF = Fmax ?

Increase F

Without EMIWith EMIFailureDetection mask*

*EMC measurement for electronic systems

Device under testWide band (calibrated) antenna

Power supply, DUT control

AbsorbentsR = 3 ou 10 m1 m1 m1 mFaraday cage (with absorbents: semi-anechoic chamber)(Siepel)Radiated immunity in (semi-)Anechoic chamber (30 MHz 1 GHz)Power amplifier ( > 100 W)Signal synthesizerField monitoringTypical max. RI level:Commercial product: 3 10 V/mAutomotive (ISO-11452-2): 25 200 V/mMilitary (MIL-STD461E): 20 200 V/mAeronautics (DO160-D): 8 800 V/m*

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Injection clampInduced RF currentBus, cableMicrocontrolerFailure ?

Measurement clampDirectional couplerSignal synthesizer

RF disturbanceLoadLISNInduced current measurementInterface circuit

Faraday cageUsually, the max. current is between 50 mA and 300 mA.

EMC measurement for electronic systemsImmunity measurements Bulk current injection (BCI)Power amplifier*

*EMC measurement for electronic systemsImmunity measurements Pulse, ESD, bursts, surgePulse waveforms and severity levels defined by standards such as IEC61000-4-x or ISO7637

Ideal ESD waveform at 4 KV (IEC61000-4-2) (level 2)Tr = 0.8 nsI30 = 8 AI60 = 4 AIpeak = 15 AIdeal Fast transient / burst (IEC61000-4-4) (level 2)Vpeak = 1 KV (on 50 )Vpeak = 1 KV (on 50 )Tr = 5 nsRepetition rate = 5 100 KHzTd= 50 ns*

*EMC measurement for integrated circuitsWhy testing EMC for ICs ?Integrated circuits are often the main cause of disturbances in electronic equipment. In recent years, there has been a strong demand for simple, reliable and standardized measurement methods focusing only on integrated circuits that electronic system designers could use to:

Obtain quantitative measure of emission/immunity from ICs establishing a uniform testing environmentQualify the low emission and high immunity performance of circuit.Optimize circuit placement, routing, filtering and decoupling components Evaluate the impact of IC redesign, technology improvement or package modification.

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*EMC measurement for integrated circuitsWhy testing EMC for ICs ?Based on pre existing standards, such as:

CISPR 25 Radio disturbance characteristics for the protection of receivers used on board vehicles, boats and on devices Limits and methods of measurementsIEC 61000-4 Electromagnetic Compatibility (EMC) Part 4: Testing and measurement techniquesISO 11452 part 1 to 7, Road vehicles Electrical disturbances by narrow band radiated electromagnetic energy Component test methods

Measurement methods for EMC of Ics proposed by IEC:

IEC 61967:Integrated circuits -Measurement of electromagnetic emissions, 150 kHz to 1 GHz. IEC 62132: Integrated circuits - Measurement of electromagnetic immunity, 150 kHz to 1 GHz.

IEC 62215: Integrated circuits Measurement of impulse immunity

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*International standards for IC emission measurement methodsEMC measurement for integrated circuits*

IEC 61967-2 (TEM : 1GHz)IEC 61967-2(GTEM 18 GHz)IEC 61967-5 (WBFC, 1 GHz)IEC 61967-8 (IC-Stripline, 3/6 GHz)IEC 61967-3(Near field scan, 1/5GHz)IEC 61967-6 (Magnetic field probe, 1GHz)IEC 61967-4 (1/150 ohm, 1 GHz)IEC 61967-7 (Mode stirred chamber, 1 GHz)

*EMC measurement for integrated circuitsIC Conducted emissionOscillatorDigital CoreI/ODriverVddCoreVdd osc

PCB lineLoadLoadIntegrated circuitTwo noise sources: internal activity (power supply noise) and I/O switching (Simultaneous Switching Noise, I/O line excitation)

Characterization of transient current and voltage induced by ICs.

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*EMC measurement for integrated circuitsLocal groundIC Conducted emission - IEC 61967-4 1 ohm / 150 ohms method

ICPCBDecouplingConducted emission is produced by RF current induced by IC activity.

The current induced voltage bounces along power distribution network and radiated emission.

The 1 ohm method aims at measuring the RF current flowing from circuit Vss pin(s) to the ground reference.

VddGlobal ground*

*IC Conducted emission - IEC 61967-4 1 ohm / 150 ohms method

I/O bufferExternal loadI/O switching is a major contributor to conducted emission. They induced voltage fluctuation along power supply and I/O lines.

The 150 ohms method aims at measuring the RF voltage induced at one or several IC output.

VddPCBDecoupling

EMC measurement for integrated circuits*

*IC current extraction from 1 probe measurementdsPIC33F: measurement in time domain and frequency of the voltage across the 1 probe proportional to the IC current.


*IC Radiated emission - IEC 61967-2 TEM cellIC under testTest boardRelation between the voltage measured by the spectrum analyzer and the radiated emission from the circuitEMC measurement for integrated circuits*

*TEM cell EM field inside the waveguideseptumAperture for DUTPort1Port250 50 yz

yx

Tapered transitionTapered transition

EHOField repartition:

Quasi homogeneous fieldR.J. Spiegel, and al.,A Method for Calculating Electric and Magnetic Fields in TEM Cells at ELF, IEEE Trans. on EMC, Nov. 1987TEM propagation mode up to 1 GHz|E/H| = 377

W = 15 cm, T = 9 cm, Wsept = 10 cm, V = 1 V, y = 8 cmWseptT WEMC measurement for integrated circuits

*TEM cell Field coupling with a DUTExample: coupling with a 50 microstrip lineDimensions of the microstrip: W = 2.5 mm, L = 75 mm, h = 1.6 mm, epsr = 4.5

septumPort150 load50 loadPort2 VNANear endFar end

Appearance of non TEM propag. mode+ 20 dB/dec.EMC measurement for integrated circuitsThe magnetic field coupling depends of the orientation of the line in the TEM cell.

*International standards for IC susceptibility measurement methods


IEC 62132-3(BCI, 1 GHz)IEC 62132-4(DPI : 1 GHz)IEC 62132-2 (TEM - GTEM : 1 / 18GHz)IEC 62132-8 (IC-Stripline, 3/6 GHz)IEC 62132-5 (WBFC, 1 GHz)IEC 62132-6 (LIHA, 10GHz)IEC 62132-9 (Near-field scan, 1/5 GHz)IEC 62132-7 (Mode stirred chamber, 1 GHz)

*Victim circuitElectronic equipmentCablesPCBRadiated disturbances

Induced conducted disturbances

Conducted immunityApplying conducted disturbances directly to IC pin ?

*EMC measurement for integrated circuits*

*Conducted immunity - IEC 62132-4 Direct Power Injection (DPI)DPI Capacitor ( 1 10 nF)

Decoupling networkChip under test

PforwPreflDirectional couplerSignal SynthesizerAmplifierFailure detectionOscilloscopeAcquisition card

> 400 Test on 1 pinIndividual test of each sensitive IC pin.


*Conducted immunity - IEC 62132-4 Direct Power Injection (DPI)Forward power limitExample : DPI test on the power supply of an RF deviceSimple, repeatable, low power measurementIC prequalification test


*Conducted immunity - IEC 62132-4 Direct Power Injection (DPI)EMC measurement for integrated circuits*

ClassFwd Power (dBm - RMS)Voltage (V) (across 50 )I/O type protection level130 - 3710 - 22Low filtering, pin connected to long cable harness (power circuit)220 273 7Short connections, low filtering (signal conditioning, communication line driver)310 - 171 - 2No direct connection with the environment

*Case study Starcore EMC testingThe Starcore is 16-bit micro-controller used in automotive industry:16 bit MPU with 16 MHz external quartz, on-chip PLL providing internal 133 MHz operating clock 128 Kb RAM, 3 general purpose ports (A, B, C, 8 bits), 4 analog inputs 12 bits, CAN interfacePrepare an EMC test plan: conducted emission (1 /150 ) and susceptibility test (DPI)


SIGNALDescriptionVDDPositive supplyVSSLogic GroundVDD_OSCOscillator supplyVSS_OSCOscillator groundPA[0..7]Data port A (programmable drive)PB[0..7]Data port B (programmable drive)PC[0..7]Data port C (programmable drive) external 66MHz data/addressADC In[0..3]4 analog inputs (12 bit resolution)CAN TxCAN interface (high power, 1MHz)CAN RxCAN interface (high power, 1MHz)XTL_1, XTL_2Quartz oscillator 16MHzCAPAPLL external capacitanceRESETReset microcontroller

Conducted emission test:> 1 ohm: on Vss pins to characterize the current returning to gnd from the IC. Can be global (connect Vss and Vss_osc) together, or separate characterization of each Vss pins> 150 ohms: to characterize voltage fluctuations on power supply pins (Vdd_osc, Vdd) and digital I/Os configured as output buffer: if the same I/O model is used for every I/Os of the IC, only one 150 ohm probe can be placed. CAN TX has certainly a different model than PA, PB, PC pin one test on CAN Tx + one test on a general purpose output. If different I/O drive options are used, the conducted emission tests should be done for the different drive options.> optional: Capa pin because some charge can be provided by the capacitor circulation of current noise.

Conducted susceptibility test (DPI): > power supply pins (Vdd_osc and Vdd): class 2 or 3 (depending on the connection to the DC source, regulator)> one digital I/O (PA, PB, PC): class 1 or 2 (if connected by a long PCB track)> one analog input (ADC): class 1 or 2 (if connected by a long PCB track)> CAN Tx and CAN Rx: class 2 (if connected by a long PCB track)> RESET : it is a very sensitive for the application: class 2 (if connected by a long PCB track)> XTL1-XTL2: class 1

The noisy equipment with CE mark has certainly passed a radiated emission test in anechoic chamber, so its emission level is certainly less than a given electric field at 900 MHz. We should know the standard followed during the EMC test to deduce the radiated field. An interference can arise if this noisy equipment placed close to the receiver produces an E field larger than the receiving limit of the receiver. Lets compute the minimum E field that the receiver can detect: the noise floor is given in power on 50 ohms lets compute a voltage :V (dBV) = P (dBm) + 90 + 10log R = P (dBm) + 107 (if R = 50 ohms) Pnoise = -90 dBm Vnoise = 17 dBV. As the antenna of the receiver has an antenna factor AF = 29 dB/m > the min E field that the receiver can detect is equal to: Enoise = Vnoise + AF = 17+29 = 46 dBV/m.The graph gives the radiated emission limit at 1 m from 3 different standards (class corresponds to different level of severity of the standard):

> CISPR22: this product standard is dedicated to ITE (information technology equipment). The level given by this standard are larger than the noise floor of our radio receiver, so an interference can arise. This standard certainly dont consider the possibility of the presence of a radio receiver at proximity of the ITE equipment. Placed at 3 m, the E field is reduced by 3 - 9dB, so the interference risk is reduced.

> CISPR 25 : this product standards concerned any components or electronic modules placed on board of a vehicle and is dedicated to protection of radio receivers. The max. limit for the radiated emission is between 25 and 49 dBV/m at 1 m depending on the severity class, our receiver is protected at 1 m of our equipment.

> MIL-STD-461E: this is a military standard. The max. level is between 44 and 64 dBV/m possibility of interferences.Conducted emission test:> 1 ohm: on Vss pins to characterize the current returning to gnd from the IC. Can be global (connect Vss and Vss_osc) together, or separate characterization of each Vss pins> 150 ohms: to characterize voltage fluctuations on power supply pins (Vdd_osc, Vdd) and digital I/Os configured as output buffer: if the same I/O model is used for every I/Os of the IC, only one 150 ohm probe can be placed. CAN TX has certainly a different model than PA, PB, PC pin one test on CAN Tx + one test on a general purpose output. If different I/O drive options are used, the conducted emission tests should be done for the different drive options.> optional: Capa pin because some charge can be provided by the capacitor circulation of current noise.

Conducted susceptibility test (DPI): > power supply pins (Vdd_osc and Vdd): class 2 or 3 (depending on the connection to the DC source, regulator)> one digital I/O (PA, PB, PC): class 1 or 2 (if connected by a long PCB track)> one analog input (ADC): class 1 or 2 (if connected by a long PCB track)> CAN Tx and CAN Rx: class 2 (if connected by a long PCB track)> RESET : it is a very sensitive for the application: class 2 (if connected by a long PCB track)> XTL1-XTL2: class 1

EMC Part3 Measurement Methods Oct12

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Transcript of EMC Part3 Measurement Methods Oct12