Automotive Environment Herman Casier AMI Semiconductor Belgium

Automotive Environment Herman Casier AMI Semiconductor Belgium
Electronic Circuits in an Automotive Environment Herman Casier AMI Semiconductor Belgium 1

Outline 1 Introduction Cost and Time To Market Quality and Safety
Automotive Market and trends Characteristics of Electronics in a car Automotive Electronics Challenges Cost and Time To Market Quality and Safety Quality requirements Safety requirements DFMEA 2

Outline 2 High Voltage : the car battery High Temperature requirements
History of the car battery Why switching over to 42V PowerNet Specifications of car-batteries Example: lamp-failure detector Example: high-side driver High Temperature requirements Temperature range specification Functionality and reliability limits Diode leakage currents Example: bandgap circuit Example: SC-circuit

Outline 3 EMC general EME – Electro Magnetic Emission
Definition of EMC Compliance and pre-compliance tests EMC standards EMC standards in IC-design EME – Electro Magnetic Emission 1W/150W test method EME what happens? EME how to cope with? Example: digital circuit current peaks Example: CANH differential output

Outline 4 EMS – Electro Magnetic Susceptibility
DPI – Direct Power Injection method EMS compliance levels EMS what happens? EMS how to cope with? Example: rectification of single ended signal Example: rectification of differential signal Example: substrate currents in ESD diodes Types of substrate currents Example: jumper detection

Outline 5 Automotive transients (ISO-7637) (sometimes called Schaffner pulses) Transient pulse definitions Transient pulses what happens? Example: supply & low-side driver Example: bandgap circuit Acknowledgments References

Trends in automotive CAR Technology TRAFFIC DRIVER SKILLS
> mechanical system very low very high technical skills > pneumatic systems low high technical skills + hydraulic systems low driving skills > electric systems increasing good technical skills increasing driving skills > electronic systems congestion low technical skills + optronic systems starts high driving skills > nanoelectronics congested very low technical skills + biotronic systems optimization decreasing driving skills starts > robotics maximal and no technical skills + nanotechnology optimized no driving skills

Automotive Electronics
Phase 1: Introduction of Electronics in non-critical applications Driver information and entertainment e.g. radio, Comfort and convenience e.g. electric windows, wiper/washer, seat heating, central locking, interior light control …  Low intelligence electronic systems  Minor communication between systems (pushbutton control)  No impact on engine performance  No impact on driving & driver skills

Phase 2: Electronics support critical applications Engine optimization: e.g. efficiency improvement & pollution control Active and Passive Safety e.g. ABS, ESP, airbags, tire pressure, Xenon lamps … Driver information and entertainment e.g. radio-CD-GPS, parking radar, service warnings … Comfort, convenience and security: e.g. airco, cruise control, keyless entry, transponders …  Increasingly complex and intelligent electronic systems  Communication between electronic systems within the car  Full control of engine performance  No control of driving & driver skills But reactive correction of driver errors.  Electronics impact remains within the car

Phase 3: Electronics control critical applications Full Engine control e.g. start/stop cycles, hybrid vehicles … Active and Passive Safety e.g. X by wire, anti-collision radar, dead-angle radar … Driver information and entertainment e.g. traffic congestion warning, weather and road conditions … Comfort and convenience  Very intelligent and robust electronics  Communication between internal and external systems Information exchange with traffic network  Full control of engine performance  Control of driving and (decreasing) driving skills Proactive prevention of dangerous situations inside and around the car  Full control of car and immediate surroundings

Phase 4: Fully Automatic Driver (1st generation)  Traffic network takes control of the macro movements (upper layers) of the car  Automatic Driver executes control of the car and immediate surroundings (lower and physical layers) ADAM : Automatic Driver for Auto-Mobile or EVA : Elegant Vehicle Automat  Driver has become the Passenger for the complete or at least for most of the journey  Driver might still be necessary if ADAM becomes an Anarchistic Driver And Madman or EVA becomes an Enraged Vehicle Anarchist

Automotive Drivers Safety (FMEA) Increasing Complexity
 level 1: remains “in-spec” in Harsh environment Increasing Complexity  more functions and more intelligence : makes the car system more transparant for the driver Increasing Accuracy  More, higher performance sensors : cheapest sensors require most performance Low cost and Time-To-Market (of course) Legislation Safety Increasing Complexity  more functions / preferably digital  more intelligence needed for the cooperation between the functions  more intelligence needed to make the system more transparent for the driver Increasing Accuracy  More sensors interfaces in a car more performance for the analog circuits cheapest sensors require most performance Low cost (of course) Decreasing time to market Safety issues (FMEA)

Automotive IC’s HBIMOS (2.0µm) I2T (0.7µm) I3T (0.35µm)

Year of Market Introduction
Technology Evolution Feature size trend versus year of market introduction for mainstream CMOS and for V automotive technologies 2000 2010 1990 1980 0.1 1.0 10 Technology Node (µm) BIMOS-7µm SBIMOS-3µm HBIMOS-2µm I2T-0.7µm I3T-0.35µm CMOS Year of Market Introduction  Changed to 2-3 generations according P. Moens. Techno roughly 2 to 3 generations behind (~7 years cfr. P. Moens) This results in a strong push for deep submicron and to split the module in a dense low voltage part and a less dense high voltage part This also results in a smaller area for the HV chips than mainstream CMOS since if the digital grows too big, it is advantageous to split the chip in two (area is usually, but not always, less of a problem) The typical chip area though grows since the analog area though grows due to increased analog functionality and analog preprocessing before the ADC, due to the increased accuracy of the analog interface and signal processing functions, due to the lower noise requirements of the Low Frequency signals. We are fortunately at 3.3Volt not yet in the place where the low supply starts to increase the area. Originally Bipolar process with HV epi /BLN / deep isolation (7u … 2u) Bipolar power drivers loose out against DMOS drivers  technology change to CMOS with extra DMOS process steps : HV by extra process steps before the CMOS Usually extra analog steps (Capa , HIPO , … ) after the CMOS processing Sometimes extra steps for EEPROM & Flash or no steps for zapping memory … Actual CMOS base, HV steps before, optimized DMOS structure, extra measures for ESD protections, extra analog steps & NASTEE, EEPROM, FLASH capability …

Introduction Top automotive vehicle manufacturers (2000) (top 14 manufacturers account for 87% of worldwide production) Source: Automotive News Datacenter

Automotive electronic equipment revenue forecast
Introduction Automotive electronic equipment revenue forecast CAGR = 6.6% (2002–2006) Automotive semiconductor consumption forecast CAGR = 13.2% (2002–2006) Source : Dataquest December 2002

Source : Dataquest November 2002
Introduction Total semiconductor market (US$B) Source : Dataquest November 2002

Introduction Where do we find electronics in a car Compass
Interior Light System Power Window Sensor Automated Cruise Control Auto toll Payment Stability Sensing Rain sensor Entertainment Head Up Display LED brake light Dashboard controller Light failure control Backup Sensing Information Navigation Keyless entry Engine: Central locking Injection control Injection monitor Oil Level Sensing Suspension control Air Flow Throttle control Key transponder Door module Valve Control Seat control: Position/Heating Headlight: Position control Power control Airbag Sensing &Control Failure detection E-gas Gearbox: Position control Brake Pressure

Introduction Electronics are distributed all over the car-body
Distributed supply used for both power drivers and low power control systems direct battery supply for the modules: high-voltage with large variation Trend: Battery voltage from 12V  42V large supply transients due to interferences of high-power users switching or error condition (load-dump) Trend: comparable supply transients, lower load-dump transient

Introduction Modules, distributed over the car-body have to comply with stringent EMC and ESD low EME to other modules and external world low EMS (high EMI) for externally and internally generated fields High ESD and system-ESD requirements Trend: increasing EMC frequency and EMC field strength for the module. Trend: increasing ESD voltages and power Trend: more integration brings the module border closer to the chip border : the chip has to comply with higher EMC field strengths and ESD power.

Introduction Modules on all locations in the car, close to controlled sensors and actuators large temperature range: - 40 … +150°C ambient Trend: increasing ambient temperature Critical car-functions controlled by electronics Safety & reliability very important Trend: increasing safety and reliability requirements Communication speed and reliability Trend: higher speed, lower/fixed latency, higher reliability and accident proof communications

Introduction Many modules interface with cheap (large offset, low linearity) and low-power sensors High accuracy and programmability of sensor interface: sensitivity, linearization, calibration … Trend: increasing sensor interface accuracy, speed and programmability with higher interference rejection and more intelligence SOC-type semiconductors in module Lower cost mandates single chip Trend: increasing intelligence requires state-of-the-art technology with high-voltage (80V), higher temperature (175°C ambient) and higher interference rejection (EMC, ESD) capabilities

Automotive Electronics Challenges
Cost & TTM Quality & Safety Automotive IC design EMC & Automotive transients High Voltage High Temp.

Cost & Time To Market The automotive market is very cost driven : “Bill of Materials” and “Cost of Ownership” more important than component cost Time To Market is quite long : start design to production is typically 2 … 3 yrs but Time To Market is in fact “Time to OEM qualification slot” which is not flexible Prestudy, design, redesign : typ 12 … 18 month Automotive IC qualification : typ 3 … 4 month OEM qualification : typ 6 … 12 month The start of the OEM qualification is a very hard deadline

EMC & Automotive transients
Outline Cost & TTM Quality & Safety Automotive IC design EMC & Automotive transients High Voltage High Temp.

Quality and Safety Required reliability ?
Most cars actually drive less than hrs over the cars lifespan of 10 … 15 years Most electronics also only functioning during hrs but some are powered for > 10years High reliability requirements : 1ppm for production reasons (low infant mortality) for safety reasons and long lifetime (failure rate). Implications Design : 6 sigma approach Test: high test coverage (digital and analog), test at different temperatures IDDQ, Vstress for early life-time failures Packaging : high reliability

Quality and Safety Safety requirements ? Implications
If a problem affects the performance, the circuit/module functionality must remain safe (predictable behavior). Problems: circuit/system failure, EMC disturbance, car-crash (within limits) … Non-vital functions may become inoperable until the problem disappears Vital parts must remain functional Implications Fault tolerant system set-up Worst Case Design including EMC disturbance DFMEA (Design Failure Mode and Effect Analysis)

DFMEA What : Failure Mode and Effect Analysis is a disciplined analysis/method of identifying potential or known failure modes and providing follow-up and corrective actions before the first production run occurs. (D.H. Stamatis) Why : avoid the natural tendency to underestimate what can go wrong FMEA extends from subcircuit to component to system and assembly and to service, where each FMEA is an input for the next level. Design FMEA (DFMEA) concerns the component design level.

DFMEA FMEA does not include prototypes and samples because up to that point, modifications are part of the development. It is good practice though to include DFMEA already in the prestudy for its large implications on the final circuit In the automotive industry, a standardized form and procedure has been published by AIAG The header is not standardized and contains the design project references, the DFMEA version control, team and the authorization signatures. The second part includes the mandatory items

DFMEA Mandatory items for the DFMEA Functional block
Identification number Circuit part and Design function e.g. input CLCK_in, Schmitt-trigger function Actual state of the circuit (I) Potential failure mode e.g. no hysteresis or hysteresis in one direction only Potential effect of failure e.g. oscillation of clock signal [S] Severity of the failure: rank 1 … 10 e.g. 8 : critical failure: product inoperable

DFMEA Mandatory items for the DFMEA (II)
Actual state of the circuit (II) Potential cause of failure e.g. Metal 1 crack [O] likelihood of Occurrence of failure: rank 1 …10 e.g. 5 : medium number of failures likely Preventive and Detection methods e.g. digital test of input does not include hysteresis [D] likelihood of Detection of failure: rank 1 … 10 e.g. 7 : low effectiveness of actual detection method [RPN] Risk Priority Number: [RPN] = [O] x [S] x [D] e.g. 280 : high value : corrective action required

DFMEA Mandatory items for the DFMEA (III) Corrective action
recommended corrective action e.g. include hysteresis test in test-program Responsible Area or Person and Completion Date e.g. test engineer NN, wk 0324 Corrected state of the circuit Corrective action taken e.g. testprogram version B1A [O] : Revised Occurrence rank e.g. 8 (unchanged) [S] : Revised Severity rank e.g. 5 (unchanged) [D] : Revised Detection rank e.g. 1 : effect measured by standard test program [RPN] : Revised Risk Priority Number e.g. 40

DFMEA example

High Voltage : the car-battery
Some History ~ 1955: 12 Volt battery introduced for cranking large & high compression V8 engines 1994: workshops in USA and Europe to define the architecture for a future automotive electrical system. 1995: study at MIT for the optimal system.  the highest possible DC voltage is best. 1996: future nominal voltage = 42 Volt  multiple of low-cost lead-acid battery  below 60 Volt under all conditions (60V = shock-hazard protection limit for DC voltages)

The car-battery 42V = 3 X 12 V Lead-Acid Battery
March 24, 1997: Daimler-Benz presents the “Draft Specification of a Dual Voltage Vehicle electrical Power System 42V/14V” is the de-facto standard since it is supported by the > 50 consortium members ( The name: 42V = 3 X 12 V Lead-Acid Battery nominal operating voltage of a 12Volt battery is 14 Volt

Example of a dual voltage power system 14V/42V
The car-battery Example of a dual voltage power system 14V/42V The system can be equipped with two batteries or with one main battery (14V or 42V) and a smaller backup battery for safety applications …

The car-battery Forecast of the 42V vehicle share in relation to the overall vehicle production in Europe

The car-battery Why switching over to 42Volt battery ?
Electrical power consumption in a car rises beyond the capabilities of a 12Volt battery. Limit for 14V generator power ~ 3kW Mean power consumption of a luxury car ~ 1.1kW (corresponds to ~ 1,5l/100km fuel in urban traffic) The required power for all installed applications in luxury cars already exceeds the generator capability. New applications e.g. ISG (Integrated-Starter-Generator), X-by-wire, require much higher power

Alternator efficiency increases from 50% to 75% or more and creates smaller load-dump pulse (voltage supply pulse when the alternator runs at full power and the battery is disconnected) New power hungry systems possible Electro mechanical or hydraulic brakes Electric water pumps “Stop-start system”: Integrates Starter and Generator in a single unit (ISG). Electromechanical engine valve actuators ……

Most existing systems benefit from 42V Heating, ventilation and air conditioning Engine cooling (eliminates belts) Electromechanic gear shifting ….. Some systems still require 14V Incandescent ligtbulbs Low-power electronic modules Existing high-volume modules because of redesign, qualification and production costs

The car-battery Specification of the 42V battery

The car-battery Other specifications
Battery reversal: no destruction non-continuous, small voltage for 42V - continuous, full battery voltage for 12V systems Short drops: reset may occur V  16V / 100msec at 16V / 16V  30V Slow increase/decrease: no unexpected behavior V  -3V/min. & 0V  +3V/min Voltage drop test: reset behaves as expected V  30V  21V  30V  20.5V  30V  20V … and so on to … 30V  0.5V  30V  0V. Electric modules see this car-battery voltage, which is further disturbed by conductive transients (ISO7637) and by ESD pulses.

Example specification of the current 12V battery
The car-battery Example specification of the current 12V battery

The car-battery Translation of the 42V battery specification into an 80V Technology requirement

Example Lamp-failure detector Directly connected to the car-battery
Sense inputs can be above or below VDDA V(Rsense) detection Accuracy < 10mV Output: low voltage CMOS levels

Example

Example Solution based on the low impedance of the source: the comparator and level shifter extract their supply from the sensor input. ESD protection of the input with automotive-transient (Schaffner) resistant zener diodes (BVCES > 80V) Protection for automotive transients (Schaffner) of all points connected to the car-battery by relative high value polysilicon resistors. Resistors limit current during transient spikes Floating resistors can handle positive and negative spikes Accuracy not impacted if DIbxRpoly << 1mV Adaptive DV generator

High-Side Driver for external NDMOS
Example High-Side Driver for external NDMOS D Vcc Vbatt Ain Aout full swing inverter D OSC. Vcc Vbatt OFF ON external NDMOS Cext LOAD charge pump with full swing invertor ON / OFF level shifters with slew rate control

Example High-side driver for external NDMOS Simple Dixon charge pump
High voltage diodes Tank-voltage controlled by Vcc-regulator Uses a full-swing inverter (separate schematic) External tank capacitor ON / OFF control logic Controlled charge and discharge current  controlled slew rate for minimum EME Bleeding resistors for low power and high temp. Simplified schematic: no protection circuits except Vgs-zener for NDMOS no flyback & no important ground-shift between IC and Load : NDMOS cannot go below substrate

High Temperature Temperature Range Specifications Low temperatures :
Environment e.g. Nordic countries, Alaska … Typical specification: - 50degC … - 40degC High temperatures : Engine compartiment, brakes, lamps … e.g. engine switch-off stops cooling and engine heat distributes. Engine restart however must work correctly Typical specifications for Automotive ICs today : 125 … 150degC ambient with short peaks up to 170 … 200degC. (power devices go higher) Requirements are increasing.

High Temperature Requirements
T4: Temperature extremes in accordance with SAE J1211 (5…10% of 7000…12000 hours lifetime) Source: A.Blessing, AEC Workshop Nashville 2004

High temperature limitations
Functionality of on-chip components ? Bulk silicon can be used up to ~ 200 … 250degC. (with appropriate design techniques) Below the intrinsic temperature of the lowest doped regions (~200degC for 100V, ~250degC for 5V techno). The MOS transistor remains a transistor, but with decreasing Vt and decreasing mobility  increasing sub-threshold leakage  increasing area Diffusion and poly-resistors remain resistors Thin oxide capacitors remain capacitors Junction diodes remain diodes but the leakage current goes up drastically. SOI can be used up to ~ 250 … 300degC GaAs can be used up to ~ 500degC

Reliability of components and package (most important limitations only) Electromigration limits decrease  use wider metals and more VIAs  area increase of power devices. Diffusion of silicon into aluminum  using an Al/Si metallization extends the limit e.g. 1% Si – 99% Al alloy extends this to ~ 500degC. Die attach not important below 200degC.  use selected epoxies

Reliability of components and package (II) Wire bonding: the dominant failure mechanism Chemical: inter-metallic growth and void-formation increases the bondpad/bondwire contact resistance Very dependent on the type of plastic and the ionic contamination of the plastic. Thermo-mechanical: delamination of bondpad and bondwire due to stress. Very dependent on the stress characteristics of plastic, the type of package and the size of chip. Plastic encapsulation: depolymerization of the epoxy is closely linked to wire bond failure. New (green) packages are improved Low stress (delamination) Low ion impurity and ion catching (voids)

Conclusions Reliability decreases according to the Arrhenius-law reliability typically decreases by 2 for every 10degC Wire bonding in a plastic package is the limiting factor for high temperature operation current limit in production ~ 150degC for hrs. Diode leakage currents are the main limitations in circuit design. Affect biasing and matching in low-power circuits Can give rise to latch-up

Diode Leakage current Leakage current mechanisms
Moderate temperatures: Drift current ~ ni leakage current dominated by thermal generation of electron-hole pairs in the depletion region High temperatures : Diffusion current ~ ni2 leakage current dominated by minority carrier generation in the neutral region  In a single well technology is the PMOS leakage current (n-well to SP-drain) much lower than the NMOS leakage current (Epi to SN-drain) Higher n-well doping  less minority carriers n-well much thinner than epi  less carriers Hole mobility lower than electron mobility  In a twin well is the difference much smaller

Diode Leakage current Junction area 4 X 20mm Epi doping: NA=10e15/cm3 Nwell doping: ND=4x10e16/cm3 (P. de Jong - JSSC-vol 33, dec 1998) Nwell, 1.2 mm CMOS technology junction areas shown in the figure (I. Finvers - JSSC-vol 30, Feb 1995)

Example : bandgap circuit
NPN collector-substrate diode: bad N+/EPI diode, large area : leakage ~ degC/unit. E.g. for n=8 & 3.5mA/ NPN branch  10% error in current matching without extra transistor.  6.5% bandgap voltage rise. PMOS mirror, Drain/Bulk diodes: good diode with small area and balanced leakage  no mismatch PMOS bulk/epi diode leakage subtracted from the PDMOS current source excess current. NDMOS body/drain leakage in parallel with grounded current source. Drain/substrate leakage extracted from supply. High voltage, low power bandgap

Example : SC circuit Leakage currents:
OpAmp inputs: Gate Tunneling Switches: Sub-threshold leakage Drain/Bulk junction leakage Gate/Drain tunneling Impact Ionisation GIDL Capacitor plate leakage e.g. C2=2pF, 1nA leakage,  500mV/msec CM droop Switched Capacitor Circuit: the leakage sensitive points are the OpAmp input nodes in Hold mode.

EMC : Definition Definition (UK Defense Standard 59-41) “Electro Magnetic Compatibility is the ability of electrical and electronic equipments, subsystems and systems to share the electromagnetic spectrum and perform their desired functions without unacceptable degradation from or to the specified electromagnetic environment.” In other words: The Electro Magnetic Emission (EME) must be low enough, not to disturb the environment The Electro Magnetic Susceptibility (EMS) must be low enough, not to be disturbed by the environment

EMC : Examples EMS examples EME examples
Unwanted but not safety critical Car-radio, GPS … Safety-critical systems require full in-spec functionality during EMC ABS system, airbag system, Motor control … EME examples Unwanted EME sources switching of heavy or inductive loads: lamps, start-motor, ignition … fast switching circuits: digital circuits … Wanted EME sources mobile phones, CB transmitters, radio stations … :

EMC : Compliance tests Compliance tests have been standardized between the car-manufacturers, their suppliers and the government. Every car must pass these tests before it is allowed on the road Examples: Anechoic Chamber tests ( V/m) Environment tests (radio station) ……..

EMC : Pre-Compliance tests
The later EMC problems are detected, the more difficult the identification of the root-cause and the more limited and expensive the solution. At final car qualification level, many modules could cause the EMC problem and there is no time for a redesign. The only solution is adding extra shielding and anti-interference components like chokes, coils, capacitors, which is very expensive. At module qualification level, the PCB layout can be changed and extra components (chokes, coils, cap’s) can be added. This has less impact on the bill of materials but can impact the time to qualification slot.  It is mandatory to include EMC in all phases of the development : IC’s, PCB’s, modules and car-layout.  Pre-compliance tests have been standardized to enable this at module and at IC level.

EMC : Pre-Compliance tests
Pre-compliance tests agreed between car-manufacturer and module-supplier or between module-manufacturer and IC supplier.  PRO: module and IC manufacturers make portable designs  CON: tendency to end up with a chain of over-specification Of the many EMC standards, 3 standards are particularly important for IC’s. IEC for EME measurements (150kHz – 1GHz, narrow-band EME) IEC for EMS measurements (150kHz – 1GHz, narrow-band EMS) ISO 7637 for Automotive transients (EMS for power supply line disturbances)

EME standard: IEC 61967 IEC : Integrated circuits – Measurement of electromagnetic emissions 150kHz to 1GHz. Part 1: General conditions and definitions Radiated emission measurements Part 2: TEM-cell (Transversal Electromagnetic cell) Part 3: Surface scan method Conducted emission measurements Part 4: 1 Ohm/150 Ohm method Part 5: Workbench Faraday Cage method (WBFC) Part 6: Magnetic probe method

EMS standard: IEC 62132 IEC : Integrated circuits – Measurement of electromagnetic immunity 150kHz to 1GHz. Part 1: General conditions and definitions Radiated immunity measurements Part 2: TEM-cell (Transversal Electromagnetic cell) Conducted immunity measurements Part 3: Bulk current Injection method (BCI) Part 4: Direct RF Power Injection method (DPI) Part 5: Workbench Faraday Cage method (WBFC)

Transients standard: ISO 7637
ISO 7637 : Road vehicles – Electrical disturbance by conduction and coupling Part 0: General and Definitions Part 1: Passenger cars and light commercial vehicles with nominal 12 V supply voltage – Electrical transient conduction along supply lines only Part 2: Commercial vehicles with nominal 24 V supply voltage – Electrical transient conduction along supply lines only Part 3: Passenger cars and light commercial vehicles with nominal 12 V supply voltage and Commercial vehicles with nominal 24 V supply voltage – Electrical transient transmission by capacitive and inductive coupling via lines other than the supply lines.

EMC standards in design
How to include EMC in the IC development flow EMC deals with electromagnetic fields. EM noise generator emits EM-energy, wanted or unwanted. EM noise receiver susceptible to this EM-energy The coupling channel conducts EM-energy from the noise-generator to the noise-receiver via radiation or conduction. radiation EM-noise generator EM-noise receiver conduction

EM-fields are not compatible with the SPICE based simulation environment of IC-design, which is “electrical only”. At the IC level, EM-fields can be modeled by Electrical fields only since the dimensions on the chip and in the package are much smaller than the wave length of the EMC signals e.g. in air : λ = 30 1GHz >> chip dimensions  On-chip current loops are very inefficient antennas for electromagnetic emission and susceptibility. (“rule of thumb”, L < λ / 20).  The variations are quasi-stationary and a Low-Frequency modeling with L, R and C is adequate.

 Radiated emission and susceptibility is not the major problem for IC’s.  Conducted emission and susceptibility to the efficient antennas on the PCB and the cable harness is the important problem.  Two EMC conductive methods, compatible with simulation, have been standardized. IEC (1W / 150W method) IEC (DPI – Direct Power Injection) Note that ISO 7637 (Schaffner) is compatible  These methods model conducted EMC between IC and PCB, not the EM-field. Generated EM-fields are function of module and wiring layouts.  Limit setting for these methods is based on the accumulated experience of the chip and module manufacturers

System level test Radiated susceptibility TEM cell tests ISO11452 –3 Shielded chamber tests ISO11452 –2 Conducted susceptibility ISO 7637–1 Conducted and radiated emission CISPR25 Etc… IC level tests : empirical validation and theoretical analysis Susceptibility Like IEC (Direct Power Injection) Like ISO (Conductive transient pulses) Emission Like IEC (1 Ohm/150 Ohm method)

EME & EMS & Automotive transients
Outline Cost & TTM Quality & Safety Automotive IC design EME & EMS & Automotive transients High Voltage High Temp.

EME 1W / 150W test

EME 1W / 150W test 1W method measures the RF sum current in a single ground pin (RF current probe). This measures the RF return current from the various current loops (emitting antennas) of the PCB. 150W method measures the RF voltage at a single or at multiple output pins, which are connected to long PCB traces or wiring harness. (150W is the characteristic impedance of wiring harnesses in a vehicle). Various measurement configurations are used for different types of outputs.

Standard EM-field graph
emission limit example: H-12-n-O

EME what happens EME is generated by HF currents in external loops, which act as antennas. Sources of the HF currents Switching of core digital logic: glue logic, mcore, DSP, memory, clock drivers …  synchronous logic generates large and sharp current peaks with large HF content Activity of the analog core circuit  does not generate large current peaks Switching of the digital I/O pins  fast and large current peaks directly to the PCB High power output drivers  large current peaks to the PCB and wiring harness.

EME how to cope with Internal measures
Limit the switching power to the external Use low power circuits & circuit techniques - low power flip-flop, memory … - architecture with different clock domains - lower or adaptive supply voltage - …. Note: gated clocks are not efficient for EME if modes exist where all gates are open. Use a more advanced technology Use on-chip capacitors EME (HF) looks at switching power spectrum, low-power digital looks at mean dissipated power.

EME how to cope with Shape the current peaks to the external
Slow down the switching edges - MS-FF and 2phase clock - asynchronous logic - controlled edges for I/O or power driver - …. External and Chip-layout measures Differential output signals e.g. CAN, LVDS … twisted-pair like lines generate less EME and are less susceptible to EME VDD and VSS close to each other - differential signals (see above) - external decoupling easier and more efficient

EME how to cope with EME of the module is the result of the current peaks generated by the IC times the efficiency of the emitting antennas of the PCB and wiring harness. The current peaks simulated or measured with the 1W / 150W method do not predict the correct value of the emission but give a good relative indication. A correlation with the actual measured EME of the module is required. Each manufacturer specifies his own limits for the emission as simulated or measured by the IEC W / 150W method.

Example Simulated spectra
In the example, spectra of different current pulses are evaluated. The current pulses are simplified. Simulated spectra Reference current pulse in existing technology. 100mA outgoing pulse  100mV in 1W probe Distributed pulse: amp. / 2, freq. x 2  HF spectrum remains, LF spectrum changes Pulse with slower edges & same power: amp. / 2  HF spectrum lower, LF spectrum remains Same logic in newer technology (2 generations): power / 2, amp. X 1, width / 2, slopes x 2  HF spectrum higher, LF spectrum lower

Example Spectrum of different pulses reference spectrum
& distributed pulse slower pulse slopes new technology reference spectrum (100mV, nsec, 1MHz) [ E c ] distributed pulse ( 50mV, nsec, 2MHz) [ E c ] slower pulse slopes ( 50mV, 10.0nsec, 1MHz) [ E e ] new technology (100mV, nsec, 1MHz) [ F b ]

Example CANH differential and single ended output (for the given pulse mismatch) CANH – single ended output [ 5 - h ] CANH – differential output [ F – 7 – h ]

EME & EMS & Automotive transients
Outline Cost & TTM Quality & Safety Automotive IC design EME & EMS & Automotive transients High Voltage High Temp.

EMS DPI test Measurement set-up
The measurement set-up uses a power source  For Zin(DUT) > 200W, the power source can be replaced by a voltage source. For Zin(DUT) < 50W, the power source is better replaced by a current source (Norton equivalent) Note that Zin(DUT) is frequency and signal dependent

EMS DPI test Simulation models Simulation model for Zin > 200W
Guideline for amplitude AV AV = 5W DPI (level 1) AV = 0.5W DPI (level 2) AV = 50mW DPI (level 3) Simulation model for Zin < 50W Guideline for amplitude AI Pinj : required immunity level

EMS compliance levels Not all I/O pins of the IC are connected to the wiring harness and unprotected. Level 1: direct connection to the environment Level 2: direct connection to the environment but some external low-pass filtering is available. e.g. signal conditioning input stages, direct sensor interfaces … Level 3: No direct connection of the I/O to the environment. e.g. interface chips connected to sensor chips in the same module, A/D converter input stages …

EMS compliance levels EMS caused malfunction is not always detrimental
Class A: all functions of a device/system perform within the specification limits during and after the exposure to the disturbance. Class B: some functions can go temporarily beyond the specification limits during the exposure. The system recovers automatically after the exposure. Class C: some functions can go temporarily beyond the specification limits during the exposure. The system does not recover automatically but requires operator intervention or system reset. Class D: degradation or loss of function, which is not self-recoverable due to damage of the IC or loss of data.

EMS what happens The incident high-frequency electro-magnetic
power is partially absorbed in the IC and causes disturbances in different ways: Large HF voltages into a high-impedance node Large HF currents into a low-impedance node Large HF power into a node, which switches from high-impedance to low-impedance at device limits, at protection voltages or at frequency breakpoints.  Rectification/pumping, Parasitic devices/currents and Power dissipation are the three important disturbing effects of EMS

EMS what happens 1) Large HF voltages into a high-impedance node
Medium power dissipation e.g. 9% of DPI for 1kW Linear large signal behavior of components and structures in the signal path  no effect Non-linear behavior of components and structures in the signal path  rectification effects (pumping) on capacitors in the signal path. : important disturbance on a chip e.g. bias pumping Capacitive coupling input devices into the substrate e.g. large driver in the OFF state, ESD structures  substrate currents and substrate bounce : important effect for latch-up, pumping … Capacitive coupling to adjacent devices or structures e.g. Cm = 100fF gives | Zm | = 10 kW at 159MHz

EMS what happens 2) Large HF currents into a low-impedance node
Large power dissipation e.g. 83% of DPI for 10W : Important effect on chip. Linear large current behavior of components and structures in the current path  no effect Non-linear large current behavior of components and structures in the current path  rectification effects (pumping) in the signal path: important disturbing effect on a chip. Inductive coupling to adjacent devices or structures : only important for bondwires and leadframe e.g. 159MHz gives ~ 750mV in an adjacent, open wire.

EMS what happens 3) Large HF power into a node, which switches from high-impedance to low-impedance e.g. at device limits or at protection voltages or at frequency breakpoints Combines high voltage and large currents Large power dissipation in clipping devices or protection structures  Important effect clipping activates parasitic devices & current paths  large current peaks in the supply lines or other pins generates EME in other loops on the PCB.  large current peaks in the substrate through parasitic devices  important effect e.g. latch-up, substrate coupling … Nature of the signal path can change with frequency  important effect, difficult to cope with.

EMS how to cope with Guidelines
Use good large signal and HF models Include all parasitic components of the devices (internal and external) Design, simulate and layout with all parasitics Avoid rectification : make circuits symmetrical Differential circuit topologies and layout Limit voltage input range of sensitive devices such that they do not go in non-linear behavior or in degradation conditions. Limit frequency input range of sensitive devices : band-limited signals

EMS how to cope with Make circuits robust for rectification
Design for high CMRR & PSRR Keep internal node impedances low Keep sensitive nodes on-chip Avoid / control parasitic devices and currents Use protection devices that clip beyond the required EMS injection levels Make protection levels symmetrical with respect to the signal Minimize substrate currents Collect substrate currents in controlled points

Example Rectification
LF: both the NMOS/OpAmp circuit and the LP-filter follow the input variations  Iout is correct MF: the NMOS/OpAmp circuit follows Vin and conducts a linear current in the PMOS diode. VgsPMOS(Id) is non-linear and the LP-Filter output voltage is the mean of the rectified VgsPMOS (pumping)  Iout decreases HF: the NMOS/OpAmp becomes a Source follower which rectifies the input current, The rectified current is largely linearized in the PMOS diode before the LP-filter.  Iout returns to correct value LF: below LP-filter & OpAmp GBW MF: between LP-filter & OpAmp GBW HF: above LP-filter & OpAmp GBW Note: at high DPI voltages, the ESD and NMOS diodes can also rectify the current (below OpAmp GBW)

Example Current source error (filtered) as function of the DPI source voltage and frequency Effect of rectification on the output current (pumping) Iout (% of Iout without DPI source) 20 30 40 50 60 70 80 90 100 Time/µsec Iout (%) Vin : 500kHz – 1.0*Aref Vin : 500kHz – 1.5*Aref 99% 0.5 Vin 98% 95% 1.0 Vin 90% 80% 1.5 Vin 3.0 Vin 50% 2.0 Vin frequency Vin 0% 100k 1M 10M (Hz) Vin: DPI source voltage (arbitrary units)

Example Rectification in a differential comparator
Emitter follower rectification due to large Ccs of current source  replace current source by resistor

Example Further EMS improvement
Input Attenuator  large improvement (LF & HF) also for LF & HF signals beyond the supply voltages  reduced sensitivity Input Filter  large improvement (only HF) also for HF signals beyond the supply voltages  no sensitivity reduction

Example Effect of the EMS improvements
100 10 1 1M 10M 100M 1G EMI DPI source strength (relative units) frequency (Hz) 2 3 5 4 original circuit with current source current source replaced by resistor with input attenuator with input filter with input attenuator and input filter The EMI value in the graph is the maximum value of the DPI source strength for which the comparator gain > 2

Example Parasitic currents & substrate currents
Example: substrate currents in an ESD protection structure

Types of Substrate Current
Three important types of substrate current Substrate currents, injected into the substrate by a PNP transistor where the substrate is the collector, by diode breakdown, by impact ionization …  Effect: substrate biasing, which can activate other parasitic transistors or cause latch-up. Substrate currents, extracted from the substrate by a forward biased diode. This diode becomes a lateral NPN with any other neighboring N-region as collector.  Effect: extraction of currents from other distant N-regions (up to millimeters distance). Capacitive currents due to junction or oxide capacitors, coupled to the substrate.  Effect: substrate biasing (bounce) & capacitive coupling to other junctions or oxide capacitors

Example Problem: for the input strapped to ground, the output toggles from low to high for low EM injection Cause: substrate current extraction from the NMOS drain during negative pulses overrides the bias current

Example Solution: new ESD protection circuit without substrate NPN, back-to-back zener diodes and shielding of the NMOS gate.

Automotive transients
Standard test pulse 1 Disconnection of a supply from an inductive load, while the device under test remains in parallel with the inductive load (ISO 7637, part1) Standard test pulse 2 Interruption of the current in an inductor in series with the device under test (ISO 7637, part1)

Standard test pulses 3a and 3b These pulses simulate transient, occurring as a result of switching processes. They are influenced by distributed capacitances and inductance of the wiring harness. (ISO 7637, part1)

Standard test pulse 4 BATTERY VOLTAGE DROP: During motor start, the battery is overloaded and the voltage drops, especially in cold weather. (ISO 7637, part1) Standard test pulse 5 LOAD DUMP: This happens when the battery is disconnected while it is being charged by the alternator. (ISO 7637, part1)

Standard test pulses 5 : LOAD DUMP clamped Load dump amplitude depends on alternator speed and field excitation. Load dump duration depends on the time constant of the field excitation circuit and the amplitude. Today most alternators have an internal protection against load dump surge. The 6 zener diodes clamp above 24Volt. For alternators with autoprotection

Standard test pulse 7 Simulates the decrease of the magnetic field of the alternator when the engine stops. (ISO 7637, part1) Standard test pulse 6 This disturbance occurs when the ignition current is interrupted. (ISO 7637, part1) .

The customer has to define the “Level of Test” according the needs of his application. Typical requirement today: Level IV, except Load dump: Level II - III.

Transients – What happens
Automotive transients (ISO ): electrical transient conduction along the supply lines only.  other IC pins indirectly connected to supply via load devices (outputs) or sensors (inputs) ISO describes two types of pulses Pulse 4 defines the minimum battery voltage. Note: battery voltage = module supply voltage. Internal IC supply voltage = module supply – reverse battery diode – module supply regulator – internal supply regulator of the chip. Pulses 1, 2, 3a, 3b, 5, 6 and 7 describe high voltage, high power transient disturbances on the supply line.

Transients – what happens
The high voltage, very high power transient disturbances can cause excessive substrate currents and power dissipation in the IC if they exceed the voltage capability of the chip. The IC can only survive if: Transient peak voltages blocked e.g. high-voltage techno or lower level transient spec Transient voltages externally limited e.g. static with zener diodes (clamped load dump) e.g. dynamic limitation with RC (all other pulses) e.g. reverse battery protection diode Peak currents internally or externally limited e.g. series impedance of load or sensor or external R e.g. low impedance output dynamically switched-off

Automotive transients – example
Typical input supply protection reverse bias diode RC-filter (pulses 1, 2, 3a, 3b) Low-side NDMOS driver with ± 100V input range NDMOS with reverse voltage diode (PNP) NDMOS drive logic with slope control Clamp circuit to prevent lateral NPN activation during fast negative pulses below ground

Automotive transients – example
Bandgap with improved tolerance for substrate currents and temperature Transient or EMC induced substrate current extraction and high temperature leakage currents from all N/Sub diodes. (NPN collectors, PMOS N-well, NMOS S/D diffusions) Transient or EMC induced current injection into the substrate, connected to AGND. Capacitive coupling through all N/Sub diode capacitors  No direct effect on the most sensitive bandgap circuits: bipolar PTAT and OpAmp input stage.

Fully compliant Automotive EMC & Automotive transients
Result Cost & TTM Quality & Safety Fully compliant Automotive IC design Automotive IC design EMC & Automotive transients High Voltage High Temp.

Result Combination of Silicon and Design Technology for Automotive Applications

Ackowledgments This work would not have been possible without the cooperation and dedication of many colleagues at AMI Semiconductor. I would like to thank in particular: Michel De Mey, Aarnout Wieers, Geert Vandensande, Hans Gugg-Schweiger, Eddy Blansaer, Luc Dhaeze, Koen Geirnaert, Herve Branquart and many others.

References – 1 P. Thoma, “Risks for the automotive industry with regard to the market shift in world-wide semiconductor demand (in German)”, VDI Berichte nr. 1287, pp 1-12, 12 September 1996. “Potential Failure Mode and Effect analysis (FMEA)”, 3th edition, April 2001, Chrysler Corporation, ford Motor Company, General Motors Corporation. IEC , “Integrated Circuits – Measurement of Electromagnetic Emissions – 150 kHz to 1 GHz, Part 4: Measurement of Conducted Emission, 1Ohm/150Ohm Method”. IEC , “Integrated Circuits – Measurement of Electromagnetic Immunity – 150 kHz to 1 GHz, Part 4: Direct RF Power Injection Method”. ISO , ISO , Road Vehicles – Electrical Disturbance by Conduction and Coupling, vehicles with nominal 12V (part 1) and 24V (part 2) supply voltages – Electrical transient conduction along supply lines only. J. Kassakian, “Challenges of the New 42Volt Architecture and Progress on its International Acceptance”, VDI Berichte nr. 1415, pp , 08 October 1998 Hans-Dieter Hartmann, “Standardisation of the 42V PowerNet - History, Current Status, Future Action”, HDT conference "42V-PowerNet: The first Solutions", Villach, Austria, September 28-29, 1999

References - 2 K. Ehlers, “The effect of the 3-litre car on the architecture of the automotive electrical system“, 5.98, → Partner → Forum Bordnetzarchitektur Ivars G. Finvers, J. W. Haslett, F.N. Trofimenkoff, “A High Temperature Precision Amplifier”, IEEE Journal of Solid-state Circuits, vol. 30, pp , February 1995. Paul C. de Jong, “Smart Sensor systems for High-Temperature Applications”, PhD dissertation, T.U. Delft, the Netherlands, November 1998. Paul C. de Jong, Gerard C. M. Meijer, Arthur H. M. van Roermond, “A 300°C Dynamic-Feedback Instrumentation Amplifier”, IEEE Journal of Solid-State Circuits, vol. 33, pp , December 1998. “High Temperature Electronics”, edited by F.Patrick McCluskey, Richard Grzybowski, Thomas Podlesak, CRC Press, Boca Raton, Florida, 1997, ISBN W. Wondrak, A. Dehbi, G. Umbach, A. Blessing, R. Getto, F. P. Pesl and W. Unger, “Passive Components for High Temperatures: Application Potential and Technological Challenges” AEC Reliability Workshop, Nashville 2004 Ron Schmitt, “Understanding Electromagnetic Fields and Antenna Radiation takes (almost) no Math”, EDN magazine, March 2, 2000, pp

References - 3 Wolfgang Horn, Heinz Zitta, “A Robust Smart Power Bandgap Reference Circuit for Use in an Automotive Environment”, IEEE Journal of Solid-state Circuits, vol. 37, pp , July 2002. M. De Mey, “Robustness in Analog Design”, Proceedings of the 12th Workshop on the Advances in Analogue Circuit Design, AACD 2003, April 2003, Graz Austria B. Deutschmann, “Improvement of System Robustness through EMC Optimization”, Proceedings of the 12th Workshop on the Advances in Analogue Circuit Design, AACD 2003, April 2003, Graz Austria D. Temmen, “Noise rejection of clocked interference sources (in German)”, VDI Berichte nr. 1646, pp , 27 September 2001 Robert J. Widlar, “Controlling Substrate Currents in Junction-Isolated IC’s”, IEEE Journal of Solid-state Circuits, vol. 26, pp , August 1991. Bruno Murari, “Power Integrated Circuits, Problems, Tradeoffs and Solutions”, IEEE Journal of solid-state Circuits, vol 13, pp , June 1978

Automotive Environment Herman Casier AMI Semiconductor Belgium

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