IEEE EMC June 2010 Chapter Meeting Automotive … Events/IEEE_June2010_Nielsen...©Arnie Nielsen...

© Arnie Nielsen Consulting LLC1

IEEE EMC June 2010 Chapter Meeting

Automotive EMC Component Specs - A Contemporary

Perspective

Essential PCB Design Rules

IEEE_June 2010


Arnie Nielsen Consulting LLC

[email protected]

248-305-8264 (M 248-982-0401)

Instrumentation Engineer - 5 years

Powertrain Hardware-Software Electronics Design Engineer - 10 years

Tech Specialist - 22 years

• Electronic Design • EMC • Reliability• Product Assurance

Electronics - EMC Consulting - 5 years


Consulting Projects

Item Company Product

1 Compact Power Inc (LG Chem) Electric Vehicle Batter y Electronics (Volt)

2 Holley Performance Products Electronic Throttle Bod y

3 Android Industries TPMS (wheel/tire assembly line)

4 Methode Electronics Center Cluster Stack

5 Vectrix Electric Motorcycle

6 RGIS Handheld Data Terminal (inventory)

7 GHPS (KDS) BLDC, DSP Amplifier

8 Kostal Electric Vehicle Connectors

9 MRM Vehicle Internet

10 BASF Shielding

11 Cobasys Electric Vehicle Battery Electronics

12 L3 Communications Vehicle Communications

13 Haitec Taiwan OEM Vehicle

14 LiteOn Body ECU

15 Whetron Keyless Entry, Auto Wiper

16 Calsonic Entertainment

17 eCho Immobilizer

18 Delta Power Distribution

19 Advanced Microelectronics Headlight Control

20 Elitech Technology Ltd Inverter

21 Delphi Power Sliding Door

22 Clarion Car PC (Infotainment)


Meets all specifications but what are we missing ?

But it met Specification ?


Reference Sampling

Documents, Books

1. EMC Specification, EMC-CS-2009(http://www.fordemc.com)

2. EMC Design Guide for Printed Circuit Boards(http://www.fordemc.com)

3. Noise Reduction Techniques in Electronic Systems, Henry Ott

4. High Speed Digital Design, Howard Johnson

5. Introduction to Electromagnetic Compatibility, Clayton Paul

6. “In Compliance” Magazine

7. ITEM - Interference Technology


Web Sites

1. www.fordemc.com

2. www.clev.clemson.edu/emc

3. http://www.compliance-club.com/

4. http://www.interferencetechnology.com/

5. emcesd.com, Doug Smith

Organizatons

1. SAE EMC committees (EMC, EMI, EMR). Meet often, much faster publication turn around time than international organizations

2. IEEE, ISO, CISPR, others

3. SAE Reliability Committee


Summary - Punch Line

1. Specs are idealized simulations, not “real world”

2. Much of industry specs based on old issues.

3. Much time and cost spent on non value exercises by contemporary practitioners due to limited knowledge of specification history - don’t know when to “hold or fold”.

4. Little time left for “sandboxing”

5. DV testing often late in design cycle - need more simple development testing to identify issues early.

6. Meeting spec not sufficient to mitigate field issues

7. Main goal is to minimize field issues not just pass specs.

8. More efficient EMC Process improvements:• Up-front analysis, focus on contemporary

issues• Design guidelines implementation. • Simple development testing.• Realistic data analysis and acceptance criteria.


Summary of Automotive EMC History

1970’s

• Minimal electronics – radio

• Mostly concerned with ignition system interference

1980’s

• Electronics increasing - starting with electronic ignition, alternator voltage regulator, simple engine control

• Quality of IC’s and manufacturing processes not mature

• Automotive EMC design and test standards starting to be developed to address above (e.g. OEM, ISO, SAE).

• EMC evolving, many issues

1990’s

• Explosion of electronics

• Automotive electronics technology maturing - IC’s, manufacturing processes, standards, testing

• EMC specs and design practices becoming mature.


Summary of Automotive EMC History

2000’s

• Specs stabilizing, similar throughout industry.

• Minimal EMC field issues (if design guidelines followed), mostly Conducted Immunity.

• Many specialized organizations in place:

OEM/Vendor EMC staff Testing facilities/staffEquipment vendors Regulators and regulations EMC committees

• A lot of inertia, perspective limited.

• Many OEM specs and International Standards exist (Different but similar):

• Ford, Mazda, GM, Hyundai, Toyota, Honda, BMW, Nissan, etc.

• ISO, CISPR, SAE, JASO, EU, FCC, Mil-Std, etc

• EMC process has potential to be improved and simplified.


Automotive EMC Standards

SAE Document Description SAE Status

International Equiv

Vehicle J551-1 Vehicle, General & Definitions ISO 11451-1 J551-2 Ignition Interference Cancelled CISPR 12 J551-4 Radiated Emissions Cancelled CISPR 25 J551-5 Electric Vehicle Emissions J551-11 Immunity, Off-Vehicle Source Cancelled ISO 11451-2 J551-12 Immunity, On-Board Transmitter Cancelled ISO 11451-3 J551-13 Immunity, Bulk Current Injection (BCI) Cancelled ISO 11451-4 J551-14 J551-15 Immunity, ESD ISO 10605 J551-16 Immunity, Reverberation Chamber J551-17 Immunity, Power Lines

Component J1113-1 Component, General & Definitions ISO 11452-1 J1113-2 Conducted Immunity, Power Leads ISO 11452-10 J1113-3 Conducted Immunity, RF Power Injection. ISO 11452-7 J1113-4 Immunity, BCI ISO 11452-4 J1113-11 Immunity, Transients ISO 7637-2 J1113-12 Immunity, Coupling Clamp ISO 7637-3 J1113-13 ESD ISO 10605 J1113-21 Immunity, Absorber Lined Chamber. ISO 11452-2 J1113-22 Immunity, Power Lines, Magnetic Cancelled ISO 11452-8 J1113-23 Immunity, Stripline Cancelled ISO 11452-5 J1113-24 Immunity, TEM Cell ISO 11452-3 J1113-25 Immunity, Tri-Plate Cancelled J1113-26 Immunity, Power Lines, Electric J1113-27 Immunity, Reverb Chamber, Mode Stiring. J1113-28 Immunity, Reverb Chamber, Mode Tuning. ISO 11452-11 ----- Immunity, Portable Transmitters ISO 11452-9 J1113-41 Radiated Emissions, Narrowband Cancelled CISPR 25 J1113-42 Conducted Emissions, Transients ISO 7637-2 ----- Environmental Conditions and Testing for Electrical

and Electronic Equipment – Part 2: Electrical Loads ISO 16750-2


Automotive EMC Standards

The Present Status of the International Automotive EMC StandardsPoul Andersen, Poul Andersen Consulting37249 Hebel RdRichmond, Michigan 48062 [email protected]

http://www.cvel.clemson.edu/auto/auto_emc_standards.html

SAE Document Description SAE Status

International Equiv

IC J1752-1 IC, General & Definitions IEC J1752-2 IC Radiated Emissions, Loop Probe IEC J1752-3 IC Radiated Emissions, TEM Cell IEC

Misc J1812 Function Performance Status Class J2556 Power Spectral Density (PSD), RE Data Analysis J2628 Characterization, Conducted Immunity

OEM (sample) EMC-CS-2009 Ford MES PW 67600 Mazda GMW3097 GM DC-10614 Chrysler TSC7001, et al Toyota 28401NDS02 Nissan ES96200 Hyundai GS95002 BMW Other Related 2004/104/EC European EMC Directive

FCC Part 15J Emissions

Mil-Std 461 Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment

SAE J1211 Handbook for Robustness Validation of Automotive Electrical/Electronic Modules (Old version published in 1978).

4/2009


Causes - Relative Contributions

0

20

40

60

80

100

A=CustomerDoes Not Like

Product(Requirementsnot specified or

incorrect)

B=System DoesNot Fit

(Interfaces)

C=Can NotDiagnose

Problem (TroubleNot Indicated)

D=ComponentFailure

E=ManufacturingFault

Examples of top 3 causes:

A: Most american cars until recently

B: Boeing 787

C: Most automotive electronics TNI > 50 %


Test Methods/Limits Observations

• Meeting EMC specs necessary but not sufficient to mitigate field issues - Main goal is to minimize field issues not just pass specs.

• Originally, EMC for automotive electronics was poor so a lot of tests were “invented”. There were minimal design practices for automotive EMC.

• Many EMC tests are idealized simulations of the real world.

• Major purpose is repeatability, not necessarily what is required to find real world issues.

• Most OEM specs and processes are very severe, time consuming and expensive to implement.

• Diverts from time to “sand box” where many issues are found - focus on major contemporary concerns.

• Contemporary electronics much improved. EMC is minor issue compared to “Big Picture” - see figure

• DV testing often late in design cycle - need more simple development testing to identify issues early.



• EMC testing is typically the first time the system is “rung out” (system components interconnected and functionally examined).

• Testing methods have many limitations and compromises not appreciated by contemporary practitioners - don’t know when to “Hold or Fold”

• Much testing addresses old issues with limited value add especially for modules that follow known basic EMC design rules and are mature.

• Different people looking at the same data can come up with quite different conclusions depending on their background, insight and flexibility.

• Considering how EMC testing is done (test setup and limits are much more severe than real world) should have more flexibility, especially when one considers that most EMC issues are 3-6 sigma events.



• Simple pass-fail criteria (e.g. limit line) results in too much non value work (not real world issues).

• Does not indicate degree of compliance

• Hard to compare different samples - need variables data.

• Should use statistical approach to make better business decisions

• Issues not presently addressed (e.g.):

• Temperature• Combined stresses• Part degradation

• Power supply electrolytic cap• Battery impedance increase.• Cracked I/O caps• Worn out transient suppressor



• Functional Safety concerns (e.g. Toyota unintended acceleration) generating potential new set of requirements.

• Non Compliance = Prosecution

• IET 2008 Guide on EMC for functional safety (177pages)

• IEC 61508 - Functional safety of electrical/electronics/programmable electronic safety related systems (7 parts)

• ISO 26262 - Road vehicles, Functional Safety. In development, adaptation of IEC 61508. Estimated July 2011.


Conflicting Goals

• The responsibility for meeting EMC requirements is the Product Design (PD) Engineer.

• Although it is admirable for the EMC community to try and do the best job possible, it has a tendency to go to extremes regarding testing requirements and limits.

• Such EMC groups are typically a separate community and have a narrow view. This may be in conflict with some of the realities of the PD engineer

• Limited time on each project

• Must address many other design and manufacturing aspects.

• Keep to schedule.

• Keep costs down (weigh cost/benefit).

• Make a profit.


EMC Process Improvements

• Process has potential to be improved and simplified but its extremely hard to change and think “out of the box” with so much inertia (OEM/Vendor EMC staff, Testing facilities/staff, Equipment vendors, Regulators and regulations, EMC committees).

• Fundamental test concepts not embraced by EMC community but essential for field issue mitigation.

• Failures are good (early in design process) -information theory

• Randomness is good.

• Litigation fears preventing any major change

• May be perceived as making less severe.

• Opinion - not really an issue


EMC Process Improvements

• Even so, certain practices can be implemented to improve the process:

• EMC group should be integrated with systems engineering and not a separate organization (ideally co-located).

• Up-Front analysis, focus on contemporary issues.

• Verify design guidelines implementation

• Simple early development testing

• Realistic data analysis and acceptance criteria.

• If product has already passed one OEM spec, other OEM’s should accept (minor alterations).

• Limited focused testing for mature products.


EMC Process Improvements - cont’d

• One generic automotive EMC spec for the industry.

• “A Generic Automotive (Tier1) EMC Test Standard”, http://www.autoemc.net/Standards/StandardsMain.htm

• Many existing standards can make this relatively easy. Most OEM specs already use.

• Vendors can design to one spec - Lowers staffing/time/cost and results in a better product for all.

• Examples in other industries• Military = Mil-Std 461• IC’s = JEDEC• Consumer = UL standards.


Simple EMC Development Tools

RE - Magnetic Field Probes



RE - RF Detector placed on wiring



RE - Digital Radio



• Noise Generator connected to Injection Clamp

• Use for DUT Power Input Noise



Adjustable Current Injection Clamp



Magnetic Field - attach to Noise Generator



• ESD Gun - Modified Lighter

• Apply in low light to see paths


Radiated Immunity


General Setup for Radiated Immunity and Emissions


Radiated Immunity (RI) Observations

• Test not like real world

• Test = Alignment of antenna and DUT/Harness maximizes susceptibility

• Real = Random harness routing, inefficient coupling, sheet metal.

• Test = Exposes large area

• Real = Exposure to only part of system.

• OEM limits too severe (Ref Mil-Std 461 ground = 50 v/m max).

• High limit based on high power on-board transmitters (rare these days).

• Contemporary = Cell Phones (only for certain DUT’s): “Cell Phone Interference in Automotive Cabin”, Craig Fanning


Radiated Immunity (RI) Observations

• Field strength varies widely in actual vehicle - can be >100 v/m difference only a few inches apart.

• Real = Field falls off rapidly from point source.

• Field impedance (E/H) different for test vs vehicle.

• Proposal - Use more realistic data analysis based on probability of concern and realization of how limit was determined.

• Example = determine susceptibility field strength average and standard deviation.

• Only resolution needed to make engineeringbusiness decision is high, medium and low (e.g. test at 100v/m but acceptable at 80 v/m)


Example of RI Data

• Does it meet intent of 100 v/m ?• CW, 400-1000 MHz• Average = 83 v/m, Std Deviation = 13 v/m


Radiated Emissions


Radiated Emissions (RE) Observations

• Test not like real world

• Test = Alignment of antenna and DUT/Harness maximizes emissions measurements

• Real = Random harness routing, inefficient coupling, sheet metal.

• Many specs overcomplicate their RE limits by having many bands and associated limits. The limits are only applicable in a lab environment for a particular setup. In the vehicle, there are many variables which amplify or attenuate the signal..

• Limits are good only for test setup, changes with different harness lengths (up to 20 dB differences).

• “Automotive EMC Test Harnesses, Standard Lengths and their Effect on Radiated Emissions”, Martin O’Hara, James Colebrooke

• Spectrum Analyzer/Receiver not like real radio


RE Spec Limits

• The main factor that determines a spec. limit are the sensitivities of on-board or nearby radio and communication antennas and receivers.

• In the AM band, the antenna factor (ratio of antenna output voltage to field strength) plus the attenuation from the antenna to the radio due to antenna cable capacitance is about 20 dB.

• In addition, there is some attenuation between noise sources within the vehicle and the antenna due to sheet metal and differences in polarization.

• Assuming a radio sensitivity of 1 uv (0 dbuv), the limit = 30 dbuv/m (20 + 10)


RE Limits, cont’d

• For FM entertainment radio and mobile communications, the antennas and antenna cable is much more efficient (antenna factor is 0 - 6 dB) and attenuation due to the vehicle sheet metal (openings, slots) is less due to small signal wavelength.

• Assuming a 1 uv sensitivity, the limit = 10 dbuv/m.

• The limit increases at 20 db/decade at higher frequencies to account for the fact that radio receiver antenna output voltage decreases at that rate (aperture size of a tuned antenna decreases with frequency). This can be seen by the following equation which shows the (1/f) relation (20 db/decade):

e = (33 * E) / f (quarter wavelength antenna)

e = antenna output voltage, E = field strength (v/m) impinging on antenna f = frequency (MHz)


RE Spec Limits, cont’d

• The following equation provides useful conversions for testing:

dBuv/meter = dBm (reading of spectrum analyzer)+ 107 (converts power across 50 ohms of spectrum analyzer to volt) - preamp gain in db (if used) + AF in dB (antenna factor, changes with antenna/frequency)

• For example, a reading of - 60 dBm on the spectrum analyzer at 100 MHz (assuming 26 dB amplifier in series with spectrum analyzer) would be:

dbuv/meter = -60 + 107 - 26 + 14 = 35 dBuv/meter = 56 uv/meter


• Typical OEM limits are much more stringent than the FCC's, especially when one considers that FCC limits are measured 3 meters away from the radiating device and the OEM limits are at 1 meter. The typical OEM limits are more restrictive:

• Radiating devices on the vehicle are closer to radio transceivers on board the vehicle.

• A vehicle contains many radiating devices.

• Customer satisfaction

46200216 - 1000

43.515088 - 216

4010030 - 88

FCC Class B RE limits (3 meters)

10 dBV/m - 24 dBV/m3.2 - 15.8 200 - 1000

103.225 - 200

3031.60.10 - 25

dBuV/muV/mFrequency (MHz)

OEM RE limits (1 meter) typical


Example of RE Data

• Which One is Acceptable ?• Top = Few spikes over Limit, technically fails• Bottom = All spikes under Limit, technically passes


Example of Using the Wrong Part

Early detection would prevent multiple layouts


RE Data Analysis

Reference SAE J2556

• The present method of using only a limit line for determining module radiated emissions acceptance is too simplistic and is not the most effective way to make competitive business decisions. The limit line approach does not address many real issues.

• It is very difficult if not unpractical to get the same results at each frequency from different test labs for radiated emissions due to the many variables involved.

• However, it is possible to establish correlation between different labs on a statistical basis. For example, if only the highest emission levels are compared independent of the emission frequencies a higher degree of correlation is possible.

• Such an approach may be justified under the assumption that the test facility design does not significantly affect the total emissions power but mainly leads to the radiated power spectrum redistribution.


• The simplistic approach of being below a limit line may still result in instances of a customer concern.

• For example, even if the RE is all below a limit line, it is more probable that a concern would exist if there are many spectral lines close to the limit (i.e. the spectral density is high).

• Another situation that may result in overdesignwould be to fail a module that only had a few data points slightly over the limit but otherwise showed little emissions.

• There are many differences between the module test setup and the vehicle configuration (e.g. harness configuration) and it is unlikely that there is a one to one correlation between the lab and the vehicle (at each frequency).

• For example, even if a module was below a limit line using the bench test configuration, in the vehicle there may be an entirely different configuration so that those frequencies that were below the limit line are now connected to a system which more effectively radiates and results in a customer concern (and conversely).


PSD Calculation

If there are narrowband (discrete peaks) emissions above a Preferred Limit and any peak does not exceed a defined level (e.g. 6 dB) over this Preferred Limit.

There is a high density of spectral lines near the limit (e.g. within 3 dB).

1. Consider the data points in terms of (x/L) 2 where x is the value of the data point in linear terms (uv/m) and L is the preferred limit at the frequency of the data point. For example, if a data point is 20dB uv/m (10 uv/m) and the preferred limit at that frequency is 10dB uv/m (3.2 uv/m), the (x/L) 2 value would be (10/3.2) 2 = 9.8.

The squaring gives exponentially more weight to data points that are high relative to a preferred limit. It also gives an indication of spectral power hence the PSD designation (receivers are sensitive to power impinging on their antenna).

2. Compute Power Spectral Density (PSD) for a given frequency span:

PSD = ∑ (x / L) 2 / (Frequency Span / Resolution)


PSD Example


Conducted Immunity


OEM Test Name Type Parameters Ford, ES-XW7T-1A278-AC

CI 210 Sine 50-10KHz, stepped

CI 220 A1 Transient CI 220 A2 Transient CI 220 B1 Transient CI 220 B2 Transient CI 220 C Transient CI220 D-G Transient ISO 7637-2 CI 230 A-D, Pwr Cyc Complex Ramps, sine CI 260 A-C, Dropout Sq Wave CI 260 D, Dip Sq Wave CI 260 E, Bat Recov Complex Ramp CI 260 F, Random Complex BMW, GS 95002 Ripple Sine 50-20k, 1min sweep BMW, GS 95003-2 Ramp 0-Ubmax, 1v/min Engine Start Complex ISO Pulse 4 Dip, Very Brief Complex Dip, Brief Complex 0.5v steps Hyundai, ES-X82010 Voltage Fluctuaton Triangle 8-16v, 1v/sec Dip Complex Single 100ms dip (ramp) Ramp Triangle 0-12v, 0.1v/s-1v/min Engine Start Complex 5-12v Engine Start Complex ISO Pulse 4 Chattering Sq Wave 5 pulses, 10-50ms Ign Key Intermittent Sq Wave 5 pulses, 0.5-3s Instantaneous

Interrupt Sq Wave Single pulses, 1ms-20ms

GMW3172 Voltage Drop Dips 5% steps from V-min, PW=5 sec Voltage Dropout Complex Ramps Superimposed Volt Sine Sweep, 2 superimposed, 1-12KHz, 12-72KHz GMW3097, GMW3100

ISO Pulses 1-5 Transients ISO 7637-2

Nissan, 28401NDS02

ISO Pulses 1-5 Transients ISO 7637-2

Slow volt Inc/Dec Triangle V-nom to 0, 0.5v/min Re-initialization Dips 5% steps from V-nom, PW=5 sec Micro-interruptions Dropouts V-nom to 0v,

PW=10us to 300ms Starting Complex Ramps, sine Ripple Sine Sweep 50Hz-20KHz DCX, DC 10614 Transients ISO 7637-2 DCX, DC-10615DR2 Ripple Sine 15Hz-250KHz Drop Out Dips 11 to 0v, 10us-1sec Voltage Dip Dips 11 to 5.5-3v, 100us-.5s Low Voltage Mem Complex Ramp, 12.6v-6.5 Ramp up Complex Ramp (50mv max step), 0v-Vmax, .1-60sec Ramp down Complex Ramp (50mv max step), Vmin-0v

Sampling of OEM Specs - CI


Conducted Immunity Observations

• Majority of contemporary EMC field issues are in this category.

• Randomness is good for detecting issues - foreign to test community.

• Hot plugging (or missing/late ground) has been identified as major reason for Electrical Overstress

• Often misidentified as ESD

• Bosch SAE paper 2009 (2009-01-0294)

• USB and OBD (Europe) connectors use extended ground pins.


Load Dump

• Most every spec has wrong test simulator.

• Many modules over-designed using typical simulators.


Load Dump Analysis


• Load Dump is a big concern since it exposes electronic components to very high energy levels that may cause damage.

• Due to the sudden disconnection of electrical load from the alternator while operating without a battery or a discharged battery.

• These conditions can exist, for example, with a loose battery terminal, damaged battery or during a jump start.

• A simplified model of the alternator is a voltage source (Vs) in series with a resistance (function of Alternator RPM).

• Vs = Constant * Field current * alternator RPM

• If there is a sudden disconnection of load current, the alternator terminal voltage suddenly increases (voltage drop across alternator resistance decreases).

• Duration of this transient is dependent on how long it takes the field circuit to bring the alternator into normal voltage regulation (the time constant of the alternator field coil).


• A realistic simulator was determined by building actual alternator driven by electric motor and comparing results on actual DUT’s.

• Historical simulator circuits only looked at energy equivalency but this model also looked at the Action Integral.

∫ I 2 dt

• Historical simulators damaged MOV but actual alternator did not (although same energy delivered to MOV)

• Difference was Action Integral. Simulator built to give approximate same Action Integral as actual alternator.

Schaffner simulator = 38 A 2 secActual Alternator = 8New simulator = 10


Load Dump Test Procedure

Calibration:

• Set transient generator to specified voltage with the DUT disconnected and SW1 open (open circuit).

• Verify voltage waveform across R4 - with DUT disconnected and SW1 closed.

Test:

• If Central Load Dump is being evaluated, add alternator zener diode (nominal 33V peak) across DUT after calibration.

• All circuits under test shall be exposed simultaneously (at test fixture). Note that in some cases this will also subject certain DUT outputs if they are connected through a load to power.

• Connect DUT, close SW1 and subject to specified transients.

• Functionally test ESC at nominal voltage after this test.


ISO 7637

• Many specs use ISO 7637 for transients

• ISO 7637 transients too idealized

• Simulation not real or effective - charge up cap then discharge through resistor network.

• Developed in days of ignition breaker points.

• Out of date, developed over 30 years ago

• Ford EMC spec only realistic version (in appendix of latest 7637). Recreates actual mechanism

• IEEE, 2005, “Comparison of ISO 7637 Transient Waveforms to Real World Automotive Transient Phenomena” Keith Frazier, Sheran Alles


Mechanical Contact Characteristics

1. Contacts start to move apart.2. Switch current suddenly goes to zero.3. L current continues dV/dt = I / C4. Distance increases and Vf increases.5. Rise of Vf slower than rise of V (Mechanical inertia).6. Repetitive flashovers occur.7. Air breakdown means Switch voltage = 0.8. C discharges into network.9. Continues until energy dissipated and can’t

flashover.


Transients - ISO Example

Conclusion = Not realistic simulation


Inductor Suppression Diode Placement

Near inductor - provides protection for intermittent wiring harness opens. Worse for Radiated Emissions (RE). Larger loop area for fast rise/fall times.

Near driver - reduces RE


SAE J2628 Details


SAE J2628 (2007) - Characterization, Conducted Immunity

1. Addresses Major Issues

• Design Margins

• Voltage Interruptions and Transients

• Power Dropouts and Dips

• Current Draw

• Switch Input Noise

2. Existing ISO Type Transients (e.g. ISO 7637) not realistic or effective.

3. Collaborated with Ford EMC group (Keith Frazier) to develop realistic simulations.


SAE J2628, Design Margins


Design Margins Example


Chattering Relay Configuration


Power Cycle, Power Interruptions During Start-Up (Waveform F)

The purpose of this test is to verify proper DUT start-up during ignition key-on (ignition switch or relay bounce) which can be severe over the full vehicle temperature range. This is especially important for verifying proper software initialization.

Relay 2 provides the power on-off cycle and relay 1 is connected in a chattering configuration to provide the random noise representing contact bounce at power up and after.


Inductive Transients - Pulse A1, A2, C

Pulse A1 and A2 simulates the transients produced by switching off power to the DUT and an inductive load (L) that is in parallel with the DUT.

Pulse C is produced by switching off an inductive load that shares a common power feed with the DUT.


Inductive Transients - Pulse A1, A2, C

Test Mode SW1 Closed = Non Chattering Open = Chattering

SW2 Closed = 220 Ω

SW3 Closed = 10nF

SW4 Closed = 6 Ω (Hi Current) Open = 39 Ω (Lo Current)

A1 1, 2

Closed Closed Closed Closed

A1-a (1)

1 Open Open Open Closed

A2-1

1 Closed Open Open Open

A2-1, C-1 2

Closed Open Open Open

A2-1, C-1

3 Open Open Open Open

A2-2, C-2

2 Closed Open Closed Open

A2-2, C-2

3 Open Open Closed Open

(1) Special for Development Mode 1 = 0.2 Hz, 10% Duty Cycle Mode 2 = Pseudo Random Sequence Mode 3 = Same as mode 2 but with chattering relay


A1 A1a - Chattering

A2 C


Inductive Transients - Pulse B1, B2.

Note: Deleted in Ford EMC-CS-2009

Pulse B1 and B2 simulates low side switching of an inductive load and applies to DUT signal inputs that are connected across the switch (e.g. A/C clutch monitor). The pulse is produced at the start of period T1 when relay 3 contact opens. R3 provides adjustment of current through L2 to give different waveform characteristics (B1 = high current, B2 = low current).

B1 B2


SAE J2628 - Power Dropouts, Dips

• Voltage Dropouts - high impedance (open circuit) typically due to poor connections (e.g. hitting pothole).

• Voltage Dips

• Low impedance most commonly experienced during engine starting.

• These dips can also occur as a result of a poor battery connection when a high current load is activated.

• Voltage dips can also be used to evaluate DUT voltage regulator input step response by monitoring the regulator output and looking for stability (limited overshoot, limited ringing).

• These waveforms apply to all power supply andcontrol circuits.


SAE J2628 – Power Dropout, Dips

Test Up, U1 T (1) Duration Impedance Acceptance

Criteria A 13.5 100us, 300us, 500us,

1ms, 3ms, 5ms, 10ms, 30ms, 50ms

3 cycles separated by 20 s

High II

B 13.5 Same as Test A Same as Test A High II

C 13.5 100us, 200us, 400us Same as Test A High I

D 13.5, 5.0 Same as Test A Same as Test A Low II

1. Waveform transition time approximately 10us.


UP

0 V

10T 9T 8T 7T 2T T10T 9T 8T 7T 2T T

T T T T T T TT T T T T T T

10T 9T 8T 7T 2T T10T 9T 8T 7T 2T T

UP

0 V

UP

0 VT

UP

0V

T T T T T T T TT T T T T T T T

10T 9T 8T 7T 2T T10T 9T 8T 7T 2T T

U1

Pulses A, B, C, D


SAE J2628 - Current Draw

• Measure True RMS current under various voltages and temperatures

• Good indicator of:

• Normal DUT Operation

• DUT degradation

• Inadvertent design-manufacturing changes (conformity)

• Sneak paths


System Degradation Example Switch Input

• Validation typically done with “pristine switches. Open = infinity, closed = 0 ohms, minimal switch bounce.

• More realistic test configuration shown below.


SAE J2628 – Switch Input Noise

• Creates random bounce at switch transitions.

• Includes non ideal switch impedances.


Electrostatic Discharge (ESD)


• Handling - too many test strikes, cumulative damage, will only see a few (at most) in the field.

• ESD is highly variable event - many variables (e.g. humidity, approach speed, module positioning above ground plane)

• Plastic parts hold charge - use air ionizer to neutralize. Important when testing - subsequent discharges not like first one due to charge buildup.

• ESD can cause “walking wounded” - looks OK after test but fails when exposed to other stress.

• The order of applying ESD discharges (in total test sequence) is important.

• Most methods used for RF Radiated Immunity also apply to ESD protection.

• Some mechanical ESD events not tested - e.g. underhood ESD from belts/pulleys, tire/bearings, low carbon tires, fuel filter, etc.

• Hot Plugging shown to be issue - often misdiagnosed as ESD.


Spark Gap PCB - Test Configuration

SMD resistor value shift used to determine effectiveness of gap configurations

Placed on Ground Plane


A. Nielsen, 7Oct2004

ConfigurationConfigurationConfigurationConfiguration Total # HitsTotal # HitsTotal # HitsTotal # Hits Avg %Avg %Avg %Avg % Std Dev %Std Dev %Std Dev %Std Dev % Total # HitsTotal # HitsTotal # HitsTotal # Hits Avg %Avg %Avg %Avg % Std Dev %Std Dev %Std Dev %Std Dev %

1 No Spark Gap or Cap 13 10.7 3.7

2 0.005 Air Gap 33 3 2.1 33 4.6 1.9

3 Add MDB 69 0.7 0.5 66 1.1 0.6

4 0.010 Air Gap 33 5.6 2 30 6.7 1.7

5 Add MDB 72 1.1 0.9 72 1.8 1.0

6 0.015 Air Gap 33 6.7 2.4 30 7.8 2.6

7 Add MDB 72 1.3 0.9 72 2.0 0.9

PCB: 4.5 x 6 inch, Ground plane, Multiple gaps ( u nused gaps covered with Hum-Seal).Compound = MDB-06-073, Thermoset encapsulant with a dhesion additive.Resistors = 2010 SMD, 10 KMeasurement = % shift in resistor value.

Test Setups: 1. PCB raised 3/8 inch above bench gr ound plane. 2. PCB ground connected directly to be nch ground plane.

Procedure (Generally, some deviations): 6 hits, rep lace resistors before going to next set of hits.

Spark Gap Test Results

10 KV 14 KV

Conclusions:

• Spark gaps do provide some protection, especially at small gaps.

• Protection at practical gap sizes is very limited. Product may function, but is weakened (walking wounded).

• Coating spark gap with special compound improves (also protects for dendritic growth).


General Test Requirements


Monitoring

• Too much monitoring creates its own set of problems

• Spend too much time debugging specialized test software or hardware.

• Diverts from finding real concerns.

Acceptance Criteria

• Often too severe or arbitrarily chosen.

• Majority should be what the customer would notice not necessarily what the component spec limits are.

Development Testing

• Development testing should be done by design engineer - interactive process, failures are good.

• Often done without regard to the cost/time/value.

• Appreciate the need to get to root cause but sometimes it’s for the sake of satisfying an engineer’s curiosity and is not a good business decision.


Component Test Plan

The quality of event is highly dependent on preparation. Poor test preparation has historically resulted in retests and a lot of non-value work.

1.0 Introduction 1.1 Product Family Description1.2 Theory of Operation1.3 Physical Construction1.4 EMC Specification Release1.5 Approved Test Facility1.6 Component Part Number(s)1.7 Component Manufacturer(s)1.8 Component Usage

2.0 EMC Requirements Analysis2.1 Critical Interface Signals2.2 Potential Sources of Emissions 2.3 Component Surrogate selection

3.0 Test Design and Requirements 3.1 Component Operating Modes/Functional

Classifications3.2 Test Requirements3.3 Input Requirements3.4 Output Requirements3.5 Load Box/Test Support Requirements

4.0 Test Setups5.0 Test Report Requirements


Designing PCB for EMC,

Essential Design Rules

(Ref Word Document)


PCB Layout Examples - Filter Connectors (1980)


PCB Layout Examples - Radio

Old (many grounds) vs New (one good ground)


PCB Layout Examples - EEC


PCB Layout Examples - Cluster


Supplemental Product Assurance

Information

Product Assurance Robustness

(PAR)


Key Elements

• Product Assurance Robustness (PAR) Plan

• Specifically designed to address contemporary Issues. Based on case histories comparing detection capability of Traditional vs. PAR.

• Similar philosophy to best OEM’s - Focus on potential weaknesses early.

• Emphasis on Analysis and Development testing -Most “Real World’ issues not found in DV.

• Best if multi-discipline analysis by expert(s) who know what to focus on.

• Use surrogate data to reduce non-value testing.

• Reduce sample size - Allows increased monitoring and less facilities (allows more focusing on product and not on test complexity "red herring" issues).


• Focused testing and measuring degradation (not just failures).

• Addresses system interaction and degradation.

• Combines EMC and Non EMC environments.

• If fully implemented, less overall time-cost ( >50 % possible) and more effective.

• Viewed as risk since different - actually more rigorous

• Successfully used on complex programs where no OEM specs exist (aftermarket) - TacNet (Police), Dockable Family Entertainment System, etc.

• Degree of implementation depends on maturity level (experience) of OEM and Vendor.

• SAE J1211 revision (2008) and SAE J2628 (2007) reflects this philosophy.


Three PAR Stages - Summary

1. Analysis - Requirements, Thermal, Mechanical, Electrical, Reliability, Referential Data - Use of experts emphasized (electrical, mechanical, etc) to focus testing.

2. Development - Formalized testing based on analysis.

• Besides analysis, this is where real issues are identified.

• Allows max flexibility to experiment and sufficient reaction time.

• Stage where failures are good (maximize information).

• Simple and low cost techniques that requires minimal lab facilities.

• Uses Product Assurance Robustness (PAR) tester, Ref SAE J2628


Development Tests

Type ID Name Description

General G-10 Internal Inspection Solder Joints, Connectors, e tc

G-20 Functionality Emphasis on Transition States.

Characterization C-10 Design Margins Ramp Voltage, Upper-Lower Operati ng Limits (UOL, LOL) Multiple Temps, Two Methods (Rigorous, Abbreviated),Includes C-20.

C-20 Interruptions,Transients

Power Interruptions, Transients

C-30 Power Dips Various Pulse Widths and Voltages

C-50 Current Draw True RMS Current During Power On-Of f, Multiple Temps.

C-60 Overvoltage True RMS Current at 19v, 24 v, Multi ple Temps.

C-70 Reverse Battery Current

True RMS Current at -14 v

C-80 Oscillator Function Momentary Short Oscillator, Verify Recovery


Development Tests, Cont’d

Type ID Name Description

Failure Modes FM-10 Shorts to Power-Ground

0.3 ohms, Monitor Current During Shorts

FM-20 Load Faults Opens, Partial Shorts in Certain Lo ads

FM-30 Leakage Resistance All pins = 50K to Power or G round

FM-40 Sneak Paths, Opens Open Power-Ground to DUT (at DUT)

EMC-RF EMC-10 RF Immunity Bulk Current Injection (BCI)

EMC-20 Emissions Current Probe on Harness or AM/FM Radio

EMC-30 ESD Pins = +/- 10kv, Controls = +/- 15kv

EMC-40 Crosstalk Noise From Chattering Relay Coupled by Parallel Wire

Environmental Env-10 Moisture Immunity Apply Windex Directly to PCB , Verify No Combustion.

Env-20 Mechanical Disturbance

Plastic Hammer, Drop (15cm), Flexing of PCB

Env-30 Resonant Search Identify Potential Vibration I ssues

Env-40 High Temp Exposure Monitor Suspect Hot Points. Hot Box if Applicable

Env-50 Combined Envir Exposure

High Temp-Humidity-Shock


3. Validation - (Qualification, Endurance)

• This is often “Test for Success” oriented - “Feel Good” testing that can give false sense of acceptability.

• Specified by customer - Plan depends on OEM flexibility. Simplify (e.g. surrogate data, focus on what’s new, etc)


Traditional vs PAR Summary

Stage

Traditional

PAR

1. Analysis

1. Define Requirements 2. Expertise Distributed – Analysis Piecemeal 3. Little Synergy to Identify Weaknesses.

1. Define Requirements 2. Multi-Disciplined Perspective (Broad Experience). 3. Identifying Weaknesses Critical - Where to Focus.

2. Development

1. Not Required or Limited. 2. Waiting for DV to Detect Concerns.

1. Main Focus - More Important than DV 2. Formalized Series of Simple Tests. 3. Low Cost, Minimal Lab Facilities. 4. Typically Takes 3 days. 5. Failure is Good - Maximizes Information 6. Identifies Concerns Early.

3. Validation

1. Cookbook Test Procedures. 2. Late in Program 3. Large Sample Sizes. 4. "Test for Success", Feel Good Results. 5. Limited "Play Time" to Find Customer Issues. 6. Software Validation Under Pristine Conditions

1. Small Sample Size. 2. More of Systems Approach. 3. Heavy Use of Surrogate Data. 4. More Focused on Weaknesses. 5. Key Life Test Looking at Degradation (Not Failu re).


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Note - Although PAR much shorter, plan is better

(customized to address many issues not in original)

OEM Original Request PAR - OEM Approved

Analysis Moderate Similar but also Developed Focused Test Plan

Development Test Time No 24 hr (3 X 8 hr)

DV Sample Size 12 6

DV Cumulative Test Time 3000 hr 400 hr

Key Life Test Time 4800 hr 300 hr

Overall Total Test Time 7800 hr 700

Note: software validation, EMC additional


PAR Support Hardware


Product Assurance Robustness (PAR) Tester

• Based on real world issues often missed in typical Product Assurance/Validation process.

• Uses simple, low cost techniques and includes many functions in one package (does not require a test laboratory environment).

• Makes it practical for Hardware-Software Robustness and Design Margin testing throughout the design process. Enables early detection of issues and a lean testing process.

• Capability to do many OEM, ISO, etc Conducted Immunity EMC tests.

• Recreates “real world” transient events (unlike the unrealistic simulations of ISO 7637).


PAR Tester Cont’d

• Creates other waveforms via a 2 channel Arbitrary Waveform Generator (AWG) and 2 channel DC power amplifier. Fast waveforms use the Electronic Switch module.

• Evaluates non ideal DUT switch signal inputs via a 4 channel switch simulator that creates random noise on switch transitions. Also simulates non ideal switch impedances.


1. DC Power Amplifiers:

a. Power Op Amps - switching power supplies.

b. 0-20 KHz, 0-24 volts.

c. Two Channels (150 and 50 watts)

2. Arbitrary Waveform Generator (AWG):

a. 2 channels

b. PC Controlled via USB

c. Easy to use waveform editor.

3. Electronic Switch, DC voltage source

a. 1us rise/fall time

b. Capability = 10 amps

c. Voltage Source = 1.5 - 20 volts, 1.5 amp (Higher currents available via DC Amp)


4. Transient Generator: Uses inductors and relays (including chattering relay) to simulate vehicle Transients per SAE J2628 and Ford EMC spec.

5. Switch Noise Simulator:

a. Creates random bounce at switch transitions (adjustable)

b. 4 channels, separate or simultaneous activation.

c. Includes non ideal switch impedances.

Contents: Rack Assembly, Enclosure (pull handle, wheels), DC Amps, Electronic Switch, Switch Noise Simulator, Transient Generator, AWG, Waveform files, User manual. Weight approx 30 lbs

Contact:

Arnie Nielsen, (248) 305-8264, [email protected]

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