5/28/2018 Automotive_Electronics_from_Herman_Casier.ppt - slidepdf.com
El ec t r o n i c C ir c u i ts
i n an
A u t o m o t iv e En v ir o n m en t
Herman Casier
AMI Semiconductor Belgium
[email protected]
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 2
O u t l i n e 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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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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O ut l i ne 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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 4
O ut l i ne 3
EMC general
Definition of EMC
Compliance and pre-compliance tests
EMC standards
EMC standards in IC-design
EME
–
Electro Magnetic Emission
1
W
/150
W
test method
EME what happens?
EME how to cope with?
Example: digital circuit current peaks
Example: CANH differential output
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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O ut l i ne 4
EMS
DPI
–
Electro Magnetic Susceptibility
–
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 6
O ut l i ne 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
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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Tr en d s in au t o m o t i v e
> 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
CAR Technology
TRAFFIC
DRIVER SKILLS
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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A u t o m o t i v e El ec t r o n i c s
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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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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A u t o m o t i v e El ec t r o n i c s
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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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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A u t o m o t i v e El ec t r o n i c s
Phase 3: Electronics control critical applications
Full Engine control
e.g. start/stop cycles, hybrid vehicles …
Active and Passive Safety
e.g. X by wire, anti-collision radar, dead-
angle radar …
Driver information and entertainment
e.g. traffic congestion warning, weather and road conditions …
Comfort and convenience
Very intelligent and robust electronics
Communication between internal and external systems
Information exchange
with traffic network
Full control of engine performance
Control of driving and (decreasing) driving skills
Proactive
prevention of dangerous situations inside
and around the car
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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A u t o m o t i v e El ec t r o n i c s
Phase 4: Fully Automatic Driver
(1
st
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)
A D A M : A u t o m a ti c Dr i v er fo r A u t o -M o b i l e
or EVA : Elegan t Vehicle Au tom at
Driver has become the Passenger for the complete
or at least for most of the journey
Driver might still be necessary if
A D A M b e c o m e s an A n a rc h i s t i c D r i v er A n d M ad m an
o r E VA b e c o m e s a n E n r a g e d Ve h i c l e A n a r c h i s t
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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A u t o m o t i v e D r iv e r s
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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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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Automotive IC’s
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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Tec h n o l o g y Ev o l u t io n
Feature size trend versus year of market introduction
for mainstream CMOS and for 80-100V automotive technologies
2000
2010
1990
1980
0.1
1.0
10
Technology Node
(µm)
BIMOS-7µm
SBIMOS-3µm
HBIMOS-2µm
I
2
T-0.7µm
I
3
T-0.35µm
CMOS
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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I n t r o d u c t i o n
Top automotive vehicle manufacturers (2000)
(top 14 manufacturers account for 87% of worldwide production)
Source: Automotive News Datacenter - 2001
Suzuki
3,0%
Mitsubishi
2,8%
BMW
1,7%
Others
13,5%
Renault
4,1%
Honda
4,2%
Fiat
4,6%
Nissan
4,4%
Hyundai
4,2%
PSA group
4,7%
GM
14,2%
Ford
12,4%
Toyota
9,9%
VW group
8,6%
Daimler-Chrysler
7,8%
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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I n t r o d u c t i o n
Automotive 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 2006
B
$
Automotive semiconductor
consumption forecast
CAGR = 13.2% (2002
–
2006)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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I n t r o d u c t i o n
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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I n t r o d u c t i o n
Interior Light System
Auto toll Payment
Rain sensor
Dashboard controller
Automated
Cruise Control
Light failure control
Information
Navigation
Entertainment
Head 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 transponder
Door module
Keyless entry
Central locking
Throttle control
Valve Control
E-gas
Suspension control
LED brake light
Compass
Stability Sensing
Power Window Sensor
Backup Sensing
Gearbox: Position control
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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I n t r o d u c t i o n
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
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I n t r o d u c t i o n
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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I n t r o d u c t i o n
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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I n t r o d u c t i o n
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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Automotive
IC design
A u t o m o t i v e El ec t r o n i c s C h a l len g es
EMC &
Automotive
transients
Cost & TTM
Quality
& Safety
High Voltage
High Temp.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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C o s t & Ti m e To M a r k e t
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
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O utl i ne
Automotive
IC 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: 26
Q ual i ty and S afety
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 27
Q ual i ty and S afety
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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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 mode
e.g. no hysteresis or hysteresis in one direction only
Potential effect of failure
e.g. oscillation of clock signal
[S] Severity of the failure: rank 1 … 10
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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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]
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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O utl i ne
Automotive
IC design
EMC &
Automotive
transients
Cost & TTM
Quality
& Safety
High Voltage
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 36
Hi gh V ol tage : the car-b attery
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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The car-b attery
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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The car-b attery
Ex am p l e of a dual v ol tage po w er s y s tem 14V/42V
The system can be equipped with two batteries or with one
main battery (14V or 42V) and a smaller backup battery for
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 39
The car-b attery
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 40
The car-b attery
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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The car-b attery
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
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The car-b attery
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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The car-b attery
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 44
The car-b attery
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.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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The car-b attery
Example specification
of the current 12V battery
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 46
The car-b attery
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 47
E x a m p l e
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 48
E x a m p l e
Lamp
Switch
Rsense
Fuse
Vbatt
ESD
prot.
Schaffner
protection
Comp.
Level
shifter
V
generator
CMOS
logic
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 49
E x a m p l e
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 (BV
CES
> 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 I
b
xR
poly
<< 1mV
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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High-Side Driver for external NDMOS
D D D D D D D D D D
Vcc
Vbatt
Ain
Aout
full swing inverter
D D D D D D D D
D
OSC.
Vcc
Vbatt
OFF
ON
external
NDMOS
Cext
LOAD
charge pump with
full swing invertor
ON / OFF level shifters
with slew rate control
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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E x a m p l e
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 52
Automotive
IC 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: 53
H i g h T em p e r at u r e
Temperature Range Specifications
Low temperatures :
Environment e.g. Nordic countries, Alaska …
Typical specification: -
50degC …
- 40degC
High temperatures :
Engine compartiment, brakes, lamps …
e.g. engine switch-off stops cooling and engine
heat distributes. Engine restart however must
work correctly
Typical specifications for Automotive ICs today :
125 … 150degC ambient with short peaks up to
170 … 200degC. (power devices go higher)
Requirements are increasing.
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 54
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
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H i g h t em p e r at u r e li m i t at i o n s
Functionality of on-chip components ?
Bulk silicon can be used up to ~ 200 … 250degC.
(with appropriate design techniques)
Below the intrinsic temperature of the lowest doped
regions (~200degC for 100V, ~250degC for 5V techno).
The MOS transistor remains a transistor,
but with decreasing Vt and decreasing mobility
increasing sub-threshold leakage
increasing area
Diffusion and poly-resistors remain resistors
Thin oxide capacitors remain capacitors
Junction diodes remain diodes but the leakage
current goes up drastically.
SOI can be used up to ~ 250 … 300degC
GaAs can be used up to ~ 500degC
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 56
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 57
H i g h t em p e r at u r e li m i t at i o n s
Reliability of components and package (II)
Wire bonding: the dominant failure mechanism
Chemical: inter-metallic growth and void-formation
increases the bondpad/bondwire contact resistance
Very dependent on the type of plastic and the ionic
contamination of the plastic.
Thermo-mechanical: delamination of bondpad and
bondwire due to stress.
Very dependent on the stress characteristics of
plastic, the type of package and the size of chip.
Plastic encapsulation: depolymerization of the
epoxy is closely linked to wire bond failure.
New (green) packages are improved
Low stress (delamination)
Low ion impurity and ion catching (voids)
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 58
Conclusions
Reliability decreases according to the
Arrhenius-law
reliability typically decreases by 2 for every 10degC
Wire bonding in a plastic package is the
limiting factor for high temperature operation
current limit in production ~ 150degC for 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
kT
E
Ae
R
T
R
0
)
(
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 59
D i o d e L eak a g e c u r r en t
Leakage current mechanisms
Moderate temperatures: Drift current ~ n
i
leakage current dominated by thermal generation
of electron-hole pairs in the depletion region
High temperatures : Diffusion current ~ n
i
2
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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 60
Junction area 4 X 20
m
m
Epi doping: NA=10e15/cm3
Nwell doping: ND=4x10e16/cm3
(P. de Jong - JSSC-vol 33, dec 1998)
Nwell, 1.2
m
m CMOS technology
junction areas shown in the figure
(I. Finvers - JSSC-vol 30, Feb 1995)
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slide: 61
Ex a m p l e : b a n d g ap c i r c u i t
NPN collector-substrate diode:
bad N+/EPI diode, large area :
leakage ~ 50 nA @ 150degC/unit.
E.g. for n=8 & 3.5
m
A/ 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
2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 62
Leakage currents:
OpAmp inputs:
Gate Tunneling
Switches:
Sub-threshold leakage
Drain/Bulk junction
leakage
Gate/Drain tunneling
Impact Ionisation
GIDL
Capacitor plate leakage
e.g. C2=2pF, 1nA leakage,
500
m
V/
m
sec CM droop
Switched Capacitor
Circuit: the leakage
sensitive points are
the OpAmp input
nodes in Hold mode.
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slide: 63
O utl i ne
Automotive
IC design
EMC
&
Automotive
transients
Cost & TTM
Quality
& Safety
High
Voltage
High Temp.
C
f
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 64
Definition (UK Defense Standard 59-41)
“
Electro Magnetic Compatibility is the ability of
electrical and electronic equipments, subsystems and
systems to share the electromagnetic spectrum and
perform their desired functions without unacceptable
degradation from or to the specified electromagnetic
environment.
”
In other words:
The Electro Magnetic Emission (EME) must be low
enough, not to disturb the environment
The Electro Magnetic Susceptibility (EMS) must be
low enough, not to be disturbed by the environment
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 65
E M C : Exam p l es
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 … :
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 66
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)
……..
E M C
P
C
l i
t
t
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 67
E M C : P re-Com p l i an ce 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.
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 68
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)
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 69
EME st and ard : 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
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 70
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)
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 71
Tran s ients s tand ard: 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.
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 72
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
EM C
t
d
d
i
d
i
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 73
EM C s t an d ar d s i n d es i g n
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.
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 74
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
W
/ 150
W
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
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 75
EM C s t an d ar d s i n d es i g n
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)
O utl i ne
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 76
Automotive
IC design
EME
& EMS
&
Automotive
transients
Cost & TTM
Quality
& Safety
High
Voltage
High Temp.
EME 1
/ 150
test
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 77
EME 1
/ 150
test
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 78
1
W
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
W
method measures the RF voltage at a
single or at multiple output pins, which are
connected to long PCB traces or wiring
harness
. (150
W
is the characteristic impedance of
wiring harnesses in a vehicle).
Various measurement configurations are used
for different types of outputs.
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 79
S tan d ard E M -fi el d g raph
emission limit
example:
H-12-n-O
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 80
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,
m
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.
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 81
EM E h o w t o c o p e w i t h
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.
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 82
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
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 83
EM E h o w t o c o p e w i t h
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
W
/ 150
W
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
W
/ 150
W
method.
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2004 11 29 AID-EMC / HC / Electronic Circuits in an Automotive Environment
slide: 84
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
W
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
