Automotive Electronics From Herman Casier

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Transcript of Automotive Electronics From Herman Casier

Automotive Electronics 2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Electronic Circuits
in an
Automotive Environment
Herman Casier
herman_casier@amis.com
1
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Outline 1
Automotive Electronics Challenges
Quality and Safety
DFMEA
2
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Outline 2
Why switching over to 42V PowerNet
Specifications of car-batteries
Example: lamp-failure detector
Example: high-side driver
High Temperature requirements
Temperature range specification
Example: SC-circuit
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Outline 3
EMC general
Example: CANH differential output
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Outline 4
EMS compliance levels
EMS what happens?
Example: rectification of single ended signal
Example: rectification of differential signal
Example: substrate currents in ESD diodes
Types of substrate currents
Example: jumper detection
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Outline 5
Acknowledgments
References
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Trends in automotive
+ 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
+ nanotechnology optimized no driving skills
CAR Technology TRAFFIC DRIVER SKILLS
> 1891 mechanical system very low very high technical skills
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Automotive Electronics
in non-critical applications
Low intelligence electronic systems
Minor communication between systems
No impact on driving & driver skills
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Automotive Electronics
Engine optimization:
Active and Passive Safety
Driver information and entertainment
Comfort, convenience and security:
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Automotive Electronics
Full Engine control
Active and Passive Safety
Driver information and entertainment
Comfort and convenience
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Automotive Electronics
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Automotive Drivers
Safety (FMEA)
Increasing Complexity
the car system more transparant for the driver
Increasing Accuracy
Low cost and Time-To-Market (of course)
Legislation
Safety
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)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Automotive IC’s
HBIMOS (2.0µm) I2T (0.7µm) I3T (0.35µm)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Technology Evolution
2000
2010
1990
1980
0.1
1.0
10
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 …
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Introduction
(top 14 manufacturers account for 87% of worldwide production)
Source: Automotive News Datacenter - 2001
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Introduction
CAGR = 6.6% (2002–2006)
Source : Dataquest December 2002
Automotive semiconductor consumption forecast
CAGR = 13.2% (2002–2006)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Introduction
Total semiconductor market (US$B)
Source : Dataquest November 2002
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Introduction
Interior Light System
Auto toll Payment
Gearbox: Position control
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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
Safety & reliability very important
Communication speed and reliability
Trend: higher speed, lower/fixed latency, higher reliability and accident proof communications
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Automotive Electronics Challenges
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Outline
Automotive
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Quality and Safety
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 safety reasons and long lifetime (failure rate).
Implications
test at different temperatures
Packaging : high reliability
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Quality and Safety
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
DFMEA (Design Failure Mode and Effect Analysis)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
DFMEA
Functional block
Identification number
Actual state of the circuit (I)
Potential failure mode
Potential effect of failure
[S] Severity of the failure: rank 1 … 10
e.g. 8 : critical failure: product inoperable
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
DFMEA
Potential cause of failure
e.g. Metal 1 crack
e.g. 5 : medium number of failures likely
Preventive and Detection methods
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
DFMEA
Corrective action
Responsible Area or Person and Completion Date
e.g. test engineer NN, wk 0324
Corrected state of the circuit
Corrective action taken
[D] : Revised Detection rank
[RPN] : Revised Risk Priority Number e.g. 40
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
 DFMEA example
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
DFMEA example
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Outline
Automotive
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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:
nominal operating voltage of a 12Volt battery is 14 Volt
183.bin
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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 …
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
The car-battery
to the overall vehicle production in Europe
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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
……
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
The car-battery
Heating, ventilation and air conditioning
Engine cooling (eliminates belts)
Incandescent ligtbulbs
Existing high-volume modules because of redesign, qualification and production costs
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
The car-battery
Specification of the 42V battery
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
The car-battery
Other specifications
- 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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
The car-battery
Example specification
of the current 12V battery
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
The car-battery
into an 80V Technology requirement
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Example
Lamp-failure
detector
Sense inputs can be above or below VDDA
V(Rsense) detection Accuracy < 10mV
Output: low voltage CMOS levels
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Example
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Example
D
D
D
D
D
D
D
D
D
D
Vcc
Vbatt
Ain
Aout
ON / OFF level shifters
with slew rate control
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Example
Simple Dixon charge pump
External tank capacitor
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Outline
Automotive
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
High Temperature
Typical specification: - 50degC … - 40degC
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
High Temperature Requirements
SAE J1211 (5…10% of 7000…12000 hours lifetime)
Source: A.Blessing, AEC Workshop Nashville 2004
Mounting zone
Module description
Temperature zones and % of total operation time in each temperature zone
T1 (5%)
T2 (20%)
T3 (65%)
T4 (10%)
Engine Compartiment
- 40 °C
25 °C
95 °C
150 °C
- 40 °C
25 °C
120 °C
205 °C
- 40 °C
25 °C
90 °C
120 °C
- 40 °C
25 °C
90 °C
115 °C
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
High temperature limitations
(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
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
High temperature limitations
(most important limitations only)
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
use selected epoxies
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
High temperature limitations
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)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
High temperature limitations
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 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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
Diode Leakage current
Leakage current mechanisms
Moderate temperatures: Drift current ~ ni
leakage current dominated by thermal…