automotive electronics from herman casier
TRANSCRIPT
Electronic Circuits in an
Automotive Environment Herman Casier
AMI Semiconductor Belgium [email protected]
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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
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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
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Outline 3 EMC general
Definition of EMC Compliance and pre-compliance tests EMC standards EMC standards in IC-design
EME – Electro Magnetic Emission 1/150 test method EME what happens? EME how to cope with? Example: digital circuit current peaks Example: CANH differential output
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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
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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
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Trends in automotive
> 1920 + pneumatic systems low high technical skills + hydraulic systems low driving skills
> 1950 + electric systems increasing good technical skillsincreasing 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
CAR Technology TRAFFIC DRIVER SKILLS
> 1891 mechanical system very low very high technical skills
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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
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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 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
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Automotive ElectronicsPhase 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 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
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Automotive ElectronicsPhase 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
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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
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Automotive IC’s
HBIMOS (2.0µm) I2T (0.7µm) I3T (0.35µm)
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Technology Evolution Feature size trend versus year of market introduction
for mainstream CMOS and for 80-100V automotive technologies
2000 201019901980
0.1
1.0
10
Technology Node (µm)
BIMOS-7µm
SBIMOS-3µmHBIMOS-2µm
I2T-0.7µm
I3T-0.35µmCMOS
Year of Market Introduction
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IntroductionTop automotive vehicle manufacturers (2000)
(top 14 manufacturers account for 87% of worldwide production)Source: Automotive News Datacenter - 2001
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IntroductionAutomotive electronic
equipment revenue forecast
CAGR = 6.6% (2002–2006)
0
10
20
30
40
50
60
70
80
90
100
2003 2004 2005 2006
B$
Other Auto
Remote/Keyless Entry
Climate Control unit
Airbags
Dashboard Instr.
Auto Stereo
GPS
ABS
Engine Control units
0
5
10
15
20
25
2003 2004 2005 2006B$
Automotive semiconductor consumption forecast
CAGR = 13.2% (2002–2006)Source : Dataquest December 2002
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Introduction
Total semiconductor market (US$B)
0
50
100
150
200
250
300
2001 2002 2003 2004 2005 2006
Military/Aero (3%)CAGR=8% (2002-06)Industrial (7%)CAGR=12% (2002-06)Automotive (8%)CAGR=13% (2002-06)Consumer (17%)CAGR=15% (2002-06)Communications (24%)CAGR=14% (2002-06)Data Processing (41%)CAGR=12% (2002-06)
Source : Dataquest November 2002
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Introduction
Interior Light SystemAuto toll Payment
Rain sensor
Dashboard controller
Automated Cruise Control
Light failure controlInformation Navigation
EntertainmentHead Up Display
Engine: Injection control Injection monitor Oil Level Sensing Air Flow
Headlight: Position control Power control Failure detection
Brake Pressure
Airbag Sensing &Control
Seat control: Position/Heating
Key transponderDoor module
Keyless entry
Central locking
Throttle controlValve Control
E-gas
Suspension control
LED brake light
CompassStability Sensing
Power Window Sensor
Backup Sensing
Gearbox: Position control
Where do we find electronics in a car
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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
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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 powerTrend: more integration brings the module border closer to the chip border : the chip has to comply with higher EMC field strengths and ESD power.
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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
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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
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AutomotiveIC design
Automotive Electronics Challenges
EMC & Automotive transients
Cost & TTM Quality & Safety
High Voltage High Temp.
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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
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Outline
AutomotiveIC design
EMC & Automotive transients
Cost & TTM Quality & Safety
High Voltage
High Temp.
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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
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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)
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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.
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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
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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 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
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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
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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
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DFMEA example
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DFMEA example
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Outline
AutomotiveIC design
EMC & Automotive transients
Cost & TTM Quality & Safety
High Voltage
High Temp.
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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)
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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
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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 …
MStarter
GAlternator
DCDC
High Power 42 Volt loads
14 Volt loads
Battery 114 Volt
Battery 242Volt
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The car-battery
Forecast of the 42V vehicle share in relation to the overall vehicle production in Europe
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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
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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 ……
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The car-batteryWhy 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
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The car-battery
Specification of the 42V battery
0-2
maximum dynamic overvoltage (load dump)
maximum continuous generator voltage including ripple
nominal voltageminimum continuous operating voltage
minimum start voltage: 18V @ 15msec, 21V @ 500msecground
non-continuous battery reversal: -2V @ 100msec
18 21 30 50 58
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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 30V 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.
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The car-battery
Example specification of the current 12V battery
0
maximum dynamic overvoltage (load dump)
maximum continuous generator voltage
nominal voltageminimum continuous operating voltage
minimum start voltage
ground
battery reversal
7 9 19 4014
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The car-battery
Translation of the 42V battery specification into an 80V Technology requirement
0-2
+ 12V @ charge pumpfor high-side drivers ...
18 21 30 50 62
0-2 18 21 30 50 58
70 80
+ 10V margin for ESDclamping structures
fabrication margin
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Example
Lamp-failuredetector
Directly connected to the car-battery
Sense inputs can be above or below VDDA
V(Rsense) detection Accuracy < 10mV
Output: low voltage CMOS levels
levelshift
Lamp OK
Vreg
Fuse OK
CMOSlogic
V
Vref
Lamp
Switch
Rsense
Fuse
Vbatt
VDDA
Vbg
LDO
levelshift
Vreg
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Example
Lamp
Switch
Rsense
FuseVbatt
ESDprot.
Schaffnerprotection Comp.
Level shifter
Vgenerator
CMOSlogic
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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 IbxRpoly << 1mV
Adaptive V generator
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ExampleHigh-Side Driver for external NDMOS
D D DD
D D DD
D
D
Vcc
Vbatt
Ain
Aout
full swing inverter
DD
D D
DD
DD
D
OSC.
Vcc
Vbatt
OFFON
externalNDMOS
Cext
LOAD
charge pump with full swing invertor
ON / OFF level shifterswith slew rate control
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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
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Outline
AutomotiveIC design
EMC & Automotive transients
Cost & TTM Quality & Safety
High Voltage
High Temp.
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High TemperatureTemperature 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.
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High Temperature Requirements
T4: Temperature extremes in accordance with SAE J1211 (5…10% of 7000…12000 hours lifetime)
Temperature zones and % of total operation time
in each temperature zone Mounting zone Module description
T1 (5%) T2 (20%) T3 (65%) T4 (10%)
Temperate zone, thermally isolated - 40 °C 25 °C 60 °C 85 °C
Splash wall - 40 °C 25 °C 90 °C 140 °C Attached to the engine or attached to the gearbox - 40 °C 25 °C 95 °C 150 °C
Engine Compartiment
Throttle valve, close to the exhaust - 40 °C 25 °C 120 °C 205 °C
Locations exposed to heat sources - 40 °C 25 °C 90 °C 120 °C Chassis Near breaks or hydraulics - 40 °C 25 °C 105 °C 175 °C Dashboard, hat rack - 40 °C 25 °C 60 °C 110 °C
Cabin Roof under strong sun exposure - 40 °C 25 °C 90 °C 115 °C
Source: A.Blessing, AEC Workshop Nashville 2004
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High temperature limitationsFunctionality 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
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High temperature limitations
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
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High temperature limitations
Reliability of components and package (II) Wire bonding: the dominant failure mechanism
Chemical: inter-metallic growth and void-formation increases the bondpad/bondwire contact resistanceVery 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)
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High temperature limitations
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 operationcurrent limit in production ~ 150degC for 10.000 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
kTEAeRTR 0)(
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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
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Diode Leakage current
Junction area 4 X 20mEpi doping: NA=10e15/cm3 Nwell doping: ND=4x10e16/cm3
(P. de Jong - JSSC-vol 33, dec 1998)
Nwell, 1.2 m CMOS technologyjunction areas shown in the figure
(I. Finvers - JSSC-vol 30, Feb 1995)
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Example : bandgap circuit NPN collector-substrate diode:
bad N+/EPI diode, large area : leakage ~ 50 nA @ 150degC/unit. E.g. for n=8 & 3.5A/ 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
n : 1
n-1
VDD
VSS
VBG
DD
D
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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 leakagee.g. C2=2pF, 1nA leakage,
500V/sec CM droop
C2
C2
C1
C1
Switched Capacitor Circuit: the leakage sensitive points are the OpAmp input nodes in Hold mode.
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Outline
AutomotiveIC design
EMC & Automotive transients
Cost & TTM Quality & Safety
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 64
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 environmentThe Electro Magnetic Susceptibility (EMS) must be low enough, not to be disturbed by the environment
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EMC : Examples
EMS 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 … :
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 66
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 (600-700 V/m)
Environment tests (radio station)
……..
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 67
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 68
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 61967 for EME measurements
(150kHz – 1GHz, narrow-band EME) IEC 62132 for EMS measurements
(150kHz – 1GHz, narrow-band EMS) ISO 7637 for Automotive transients
(EMS for power supply line disturbances)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 69
EME standard: IEC 61967 IEC 61967 : 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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 70
EMS standard: IEC 62132 IEC 62132 : 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)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 71
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 72
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.
EM-noise generator
EM-noise receiver
radiation
conduction
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 73
EMC standards in design 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 cm @ 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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 74
EMC standards in design 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 61967-4 (1 / 150 method) IEC 62132-4 (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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 75
EMC standards in design
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 62132-4
(Direct Power Injection)
Like ISO 7637-1 (Conductive transient pulses)
Emission Like IEC 61967-4
(1 Ohm/150 Ohm method)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 76
Outline
AutomotiveIC design
EME & EMS & Automotive
transients
Cost & TTM Quality & Safety
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 77
EME 1 / 150 test
RF
curr
ent
1
4950
51
12050
6.8nF
51
11050
6.8nF30
30Spectrum analyser
Spectrum analyser
Spectrum analyser
impedance matching network for Line Driver
impedance matching network for CANH-bus
150trace
150trace
150trace
PowerSupply
LineDriver
CANH
CANL
VDD VSS
DUTpr
obe
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 78
EME 1 / 150 test 1 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.
150 method measures the RF voltage at a single or at multiple output pins, which are connected to long PCB traces or wiring harness. (150 is the characteristic impedance of wiring harnesses in a vehicle). Various measurement configurations are used for different types of outputs.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 79
Standard EM-field graph
0
6
12
18
24
30
36
42
48
54
60
66
72
78
84
105 2 3 4 5 6 8 106 2 3 4 5 6 8 107 2 3 4 5 6 8 108 2 3 4 5 6 8 109 Hz
A
B
C
D
E
F
G
H
I
K
L
M
N
O
123
4
56
78
910
1112
1314
1516
1718
19
ab
cd
efg
hik
lmn
op
qr
st
uv
wy
zf
dBV
V emission limitexample: H-12-n-O
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 80
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, core, 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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 81
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 82
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 83
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 1 / 150 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 61967-4 1 / 150 method.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 84
Example 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 1 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
pulse widthWpulse
pulse slope80% Wpulse
pulse top20% Wpulse
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 85
ExampleSpectrum of different pulses
refe
renc
e sp
ectr
um
(1
00m
V,
5.0
nsec
, 1
MH
z)
[ E
- 4
- c ]
dist
ribut
ed p
ulse
(
50m
V,
5.0
nsec
, 2
MH
z)
[ E
- 4
- c ]
slow
er p
ulse
slo
pes
(
50m
V, 1
0.0n
sec,
1
MH
z)
[ E
- 5
- e ]
new
tech
nolo
gy
(1
00m
V,
2.5
nsec
, 1
MH
z)
[ F
- 4
- b ]
0
6
12
18
24
30
36
42
48
54
60
66
72
78
84
105 2 3 4 5 6 8 106 2 3 4 5 6 8 107 2 3 4 5 6 8 108 2 3 4 5 6 8 109 Hz
A
B
C
D
E
F
G
H
I
K
L
M
N
O
123
4
56
78
910
1112
1314
1516
1718
19
ab
cd
efg
hik
lmn
op
qrs
tu
vw
yz
f
dBV
V
reference spectrum& distributed pulse
slower pulse slopes
new
tech
nolo
gy
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 86
ExampleCANH differential and single ended output
(for the given pulse mismatch)
Frequency / Hertz
0
6
12
18
24
30
36
42
48
54
60
66
72
78
84
105 2 3 4 5 6 8 106 2 3 4 5 6 8 107 2 3 4 5 6 8 108 2 3 4 5 6 8 109 Hz
A
B
C
D
E
F
G
H
I
K
L
M
N
O
123
4
5
67
89
1011
1213
1415
1617
1819
ab
cd
efg
hik
lmn
op
qrs
tu
vw
yz
f
dBV
V
CANH – single ended output [ 5 - h ]CANH – differential output [ F – 7 – h ]
CANH bus with
termination
150 method
6.8nF110
51 50
60
60 60
60
CAN driver
2.5V
CANHA=1.855Vperiod=4uwidth=2utr= 55.3ntf= 55.3n
CANLA=1.845Vperiod=4uwidth=2utr= 53.2ntf= 55n
110
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 87
Outline
AutomotiveIC design
EME & EMS & Automotive
transients
Cost & TTM Quality & Safety
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 88
EMS DPI testMeasurement set-up
The measurement set-up uses a power source For Zin(DUT) > 200, the power source can be
replaced by a voltage source. For Zin(DUT) < 50, the power source is better
replaced by a current source (Norton equivalent)Note that Zin(DUT) is frequency and signal dependent
50
directional coupler
50
DUTRF power source
PreflPfwd
C coup
le R prot
50
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 89
EMS DPI test
Simulation models
Simulation model for Zin > 200
Guideline for amplitude AV
AV = 22V @ 5W DPI (level 1) AV = 7V @ 0.5W DPI (level 2) AV = 2.2V @ 50mW DPI (level 3)
Simulation model for Zin < 50 Guideline for amplitude AI
Pinj : required immunity level
Zin50Zin50PA injI
DUTCcouple
50 Zin < 200
Ccouple Rprot DUT
Zin > 200RF voltage sourceV = AV · sin(·t)
RF current sourceI = AI · sin(·t)
50
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 90
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 …
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 91
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 92
EMS what happens The incident high-frequency electro-magnetic
power is partially absorbed in the IC and causes disturbances in different ways:
1) Large HF voltages into a high-impedance node 2) Large HF currents into a low-impedance node3) 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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 93
EMS what happens
1) Large HF voltages into a high-impedance node Medium power dissipation e.g. 9% of DPI for 1k 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 substratee.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 k at 159MHz
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 94
EMS what happens
2) Large HF currents into a low-impedance node Large power dissipation e.g. 83% of DPI for 10 :
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. 100mA @ 159MHz gives ~ 750mV in an adjacent, open wire.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 95
EMS what happens3) 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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 96
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 97
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 98
ExampleRectification
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
Vref
Rext DPIsource
IoutLP-filter
ESD
CHIP
LF: below LP-filter & OpAmp GBWMF: between LP-filter & OpAmp GBWHF: above LP-filter & OpAmp GBW
Note: at high DPI voltages, the ESD and NMOS diodes can also rectify the current (below OpAmp GBW)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 99
ExampleCurrent source error (filtered) as function of the DPI source voltage and frequency
100k 1M 10M
99%
90%
0%
50%
80%
95%
98%
frequency Vin
(Hz)
Iout (% of Iout without DPI source)
0.5 Vin
1.0 Vin
1.5 Vin
2.0 Vin
3.0 Vin
Vin: DPI source voltage (arbitrary units)
20 30 40 50 60 7040
50
60
70
80
90
100
Time/µsec
Iout (%)
Vin : 500kHz – 1.0*Aref
Vin : 500kHz – 1.5*Aref
Effect of rectification on the output current (pumping)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 100
Example
Rectification in a differential comparator
DPISource
input signal Vout
Comparator
DPISource
input signal Vout
Comparator
Emitter follower rectification due to large Ccs of current source replace current source by resistor
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 101
ExampleFurther EMS improvement
DPISource
input signal Attenuator Vout
Comparator
DPISource
input signal Filter Vout
Comparator
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 102
Example
Effect of the EMS improvements
100
10
1
1M 10M 100M 1G
EMIDPI source strength (relative units)
frequency(Hz)
1
2
35
4
(1) original circuit with current source
(2) current source replaced by resistor
(3) with input attenuator(4) with input filter(5) 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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 103
Example
Parasitic currents & substrate currents
VDD
VSS
INPUT
Isub1to Substrate
Isub2from other N-tubs
Lateral NPN
Vertical & Lateral PNPN-buried layer
N-tub N-wellP+N+P+
P-epi
P-substrate
N-buried layerN-tubN-well
P+N+P+
P-epi
P-substrate
P-wellN+N+
Example: substrate currents in an ESD protection structure
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 104
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 105
ExampleProblem: 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
Vin
Vclamp(1.5·Vbe)
Vcc
Vbat
Vbias
Vout
ESD zener diodeESD protectionfor full battery
voltageSchmitt trigger
regulator
large current pull-upIsub
Isub
Isub
Ibias
DPI Source
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 106
ExampleSolution: new ESD protection circuit without substrate NPN,
back-to-back zener diodes and shielding of the NMOS gate.
Vin
Vcc
Vbat
Vbias
Vout
back-to-back ESD zener diodes
ESD protectionfor positive and
negative battery voltages
Schmitt triggerwith shielded
NMOS-gate
regulator
large current pull-upIsub
DPI Source
LP-filter
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 107
Outline
AutomotiveIC design
EMC & Automotive transients
Cost & TTM Quality & Safety
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 108
Automotive transients
Standard test pulse 2Interruption of the current in an inductor in series with the device under test(ISO 7637, part1)
Standard test pulse 1Disconnection of a supply from an inductive load, while the device under test remains in parallel with the inductive load(ISO 7637, part1)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 109
Automotive transientsStandard test pulses 3a and 3bThese 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)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 110
Automotive transients
Standard test pulse 5LOAD DUMP: This happens when the battery is disconnected while it is being charged by the alternator.(ISO 7637, part1)
Standard test pulse 4BATTERY VOLTAGE DROP: During motor start, the battery is overloaded and the voltage drops, especially in cold weather. (ISO 7637, part1)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 111
Automotive transients
For alternators with autoprotection
Standard test pulses 5 : LOAD DUMP clampedLoad 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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 112
Automotive transients
.
Standard test pulse 7Simulates the decrease of the magnetic field of the alternator when the engine stops. (ISO 7637, part1)
Standard test pulse 6This disturbance occurs when the ignition current is interrupted.(ISO 7637, part1)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 113
Test pulses
(ISO 7637, part1) Test levels
(values agreed to between car manufacturer
and supplier)
Pulse type
Series resistance
Impulse duration
I II II IV
1 10 2 ms -25V -50V -75V -100V
2 10 50 s +25V +25V +75V +100V
3a
3b 50 0.1 s -40V
+25V
-75V
+50V
-110V
+75V
-150V
+100V
4
10 up to 20
sec 9V
(12V -3V)
7V
(12V-5V)
6V
(12V-6V)
5V
(12V-7V)
5 1
up to 400ms
+35V +50V +80V +120V
aaaaaaaaaaaaaaaaaaaa
Automotive transientsThe 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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 114
Transients – What happens Automotive transients (ISO-7637-1): electrical
transient conduction along the supply lines only. other IC pins indirectly connected to supply via load devices (outputs) or sensors (inputs)
ISO-7637-1 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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 115
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 116
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
D
Vbatt Vbat_filtered
Vcc
bandgap
regulator
Low-side Driver+/- 100V input range
NDMOS driver with negativevoltage diode
dynamic Schaffner
clampcontrol logic
(slope control)
clamp to preventsubstrate current
extraction
ONOFF
VccVbat_filtered
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 117
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.
Vbg
Vbatt
AGND
n : 1
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 118
AutomotiveIC design
EMC & Automotive transients
Cost & TTM Quality & Safety
High Voltage
High Temp.
Fully compliant AutomotiveIC design
Result
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 119
Result
Combination of Silicon and Design Technology
for Automotive Applications
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 120
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 121
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IEC 62132-4, “Integrated Circuits – Measurement of Electromagnetic Immunity – 150 kHz to 1 GHz, Part 4: Direct RF Power Injection Method”.
ISO 7637-1 , ISO 7637-2, 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.
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 122
References - 2 K. Ehlers, “The effect of the 3-litre car on the architecture of the automotive
electrical system“, 5.98, http://www.sci-worx.com → Partner → Forum Bordnetzarchitektur
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment slide: 123
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