Electronic Circuits • in an • Automotive Environment Herman Casier • AMI Semiconductor Belgium • firstname.lastname@example.org
Outline 1 • Introduction • 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
Outline 2 • High Voltage : the car battery • 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 • 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 TechnologyTRAFFICDRIVER SKILLS > 1891 mechanical system very low very high technical skills > 1920 + pneumatic systems low high technical skills + hydraulic systems low driving skills > 1950 + electric systems increasing good technical skills increasing driving skills > 1980 + electronic systems congestion low technical skills + optronic systems starts high driving skills > 2010 + nanoelectronics congested very low technical skills + biotronic systems optimization decreasing driving skills starts > 2040 + 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
Automotive Electronics 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 entertainmente.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
Automotive Electronics 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 entertainmente.g. traffic congestion warning, weather and road conditions … • Comfort and convenience Very intelligent and robust electronics Communication between internal and external systemsInformation exchange with traffic network Full control of engine performance Control of driving and (decreasing) driving skills Proactiveprevention of dangerous situations inside and around the car Full control of car and immediate surroundings
Automotive Electronics 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) 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
Automotive IC’s HBIMOS (2.0µm) I2T (0.7µm) I3T (0.35µm)
Technology Node (µm) BIMOS-7µm 10 SBIMOS-3µm HBIMOS-2µm I2T-0.7µm 1.0 I3T-0.35µm CMOS 0.1 1980 1990 2000 2010 Year of Market Introduction Technology Evolution Feature size trend versus year of market introduction for mainstream CMOS and for 80-100V automotive technologies
Introduction Top automotive vehicle manufacturers (2000) (top 14 manufacturers account for 87% of worldwide production)Source: Automotive News Datacenter - 2001
Automotive semiconductor consumption forecast CAGR = 13.2% (2002–2006) Introduction Automotive electronic equipment revenue forecast CAGR = 6.6% (2002–2006) Source : Dataquest December 2002
Introduction Total semiconductor market (US$B) Source : Dataquest November 2002
Introduction Where do we find electronics in a car Compass Power Window Sensor Interior Light System Automated Cruise Control Stability Sensing Auto toll Payment 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 Gearbox: Position control E-gas 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 yrsbut 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
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 10.000hrs over the cars lifespan of 10 … 15 years • Most electronics also only functioning during 10.000hrs 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 ? • 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 functione.g. input CLCK_in, Schmitt-trigger function • Actual state of the circuit (I) • Potential failure modee.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 … 10e.g. 8 : critical failure: product inoperable
DFMEA • Mandatory items for the DFMEA (II) • Actual state of the circuit (II) • Potential cause of failuree.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 … 10e.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 actione.g. include hysteresis test in test-program • Responsible Area or Person and Completion Datee.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
Outline Cost & TTM Quality & Safety Automotive IC design EMC & Automotive transients High Voltage High Temp.
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 • 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 (http://www.mitconsortium.org) • The name: 42V = 3 X 12 V Lead-Acid Battery nominal operating voltage of a 12Volt battery is 14 Volt
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
The car-battery Why switching over to 42Volt battery ? • 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 • ……
The car-battery Why switching over to 42Volt battery ? • 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 occur30V 16V / 100msec at 16V / 16V 30V • Slow increase/decrease: no unexpected behavior 48V 0V @ -3V/min. & 0V 48V @ +3V/min • Voltage drop test: reset behaves as expected 42V 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.
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 • 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
Vbatt Cext D D D D Vbatt D external D NDMOS D D D D Aout Vcc D D D D Vcc D D D D D LOAD OSC. ON OFF Ain charge pump with ON / OFF level shifters full swing inverter full swing invertor with slew rate control Example High-Side Driver for external NDMOS