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Sensing in Automotive -

Powertrain and Braking Systems

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Agenda

Brief Introduction

Automotive electronics & sensors

Capabilities available from ON Semiconductor

Powertrain Systems

Gasoline and diesel engines

Main powertrain sensors

Braking and Stability Control Systems

Basic systems: ABS, EBD, TCS, ESC

Sensors for dynamic braking

Examples of automotive sense interface ICs

Sensing interface IP from ON Semiconductor

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Automotive Electronics

Value added by ON Semiconductor APG

Proprietary High-Voltage Processes

Innovative Solutions: Sensor Interfaces,IVN, High-Voltage System-on-Chip

Harsh Environment Applications

Extensive Automotive Portfolio

Key Successes in sensing

Steering/Pedal Angle Sensor

Pressure sensors for Powertrain / Braking Position Sensors for Headlight Control

Gyro Sensors for Stability Control

Main drivers for new electronics

Safety Emissions

Fuel consumption

Regulation plays a key role

focus area for green electronics

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Modern Automotive Sensors

External sensing element or MEMS

Built-in protections (shorts, EMI, ESD)

Diagnostic modes / redundancy

Accuracy / linearity reaching ~0.1% to 1%

NVM for trimming and calibration

Nonlinear temperature compensation

TJ at IC: from 40o

C up to +125~200o

C Target failure rate: zero ppm

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Automotive Technologies Portfolio

I3T50

I3T80

C035

ABX

VoltageVoltage

Gate CountGate Count1K 5K 100K 500K

100 V

80 V

50 V

25 V

5 V3.3 V1.8 V

HBIMOSI2T100

C3,C035U

C07

FeaturesFeatures(OTP, EEPROM, etc.)(OTP, EEPROM, etc.)

C018

I3T25

>1.5 u 0.7 u 0.6 u 0.35 u 0.18 u Geometry(drawn poly)

D3C5X

I4TI2T30(E)

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Non-volatile Memory (NVM) IP

EEPROM

Long experience, started with C5 NASTEE release in 1999

Non-added-steps EEPROMS available today for C5 / C3 / I3T50

I3T50 EEPROM is capable of 175 oC operation (reading)

EE being released for I3T25U (Q4 2009)

Development for 0.18 u ongoing

OTP OTP is Zener diode zap

Available in I2T100, I3T25, I3T50, I3T80

Flash

Requires 5 added process steps

Special technology developed only for I3T80

Technology is qualified to 150 oC read (50 oC for write)

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I3T Example

S/H

Diag-nostics

DAC

ADCPGAAMUX

EEPROM

OTP

Temp senseHV

BUF

Logic ControlBlock

RAM

ROM orFlash

JTAG

Timer

PWM

GPIO

Comm.Control

UnitHV

LINTransceiver

LINBSD

RS-232Drivers :

MotorRelayLampHeat

Sensor Int. :

HV / LVInductiveCapacitiveResistive

Temperature

Analog Controland Signal Processing :

Voltage regulatorsAmpl if iers, comparatorsADC, DACFilters (SC, GMC, RC)

Vbat 5 VRegulator

ARM7R8051P

eripheralExtension

PeripheralExtension

Digital Signal Processingand Control :

State Machine oruController based

Vdc < 65V/36V/18V

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Gasoline Engine System Concept

Source: Continental

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Diesel Engine

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The Internal Combustion Engine

Nikolaus Otto Rudolf Diesel

HeatOHy

xCOOy

xHC yx +

+

++ 222 24

Chemical equation forstoichiometric hydrocarbon burning

Partial combustion

Fuel evaporation

Nitrogen from air

Sulfur from fuel

HC Hydrocarbons (unburned)

CO Carbon monoxide

NO, NO2 Nitrogen oxides (NOx)

SO2 Sulfur dioxide

Diesel particulate matter (DPM)

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Electronic Fuel Injection (EFI)

Stringent emission regulations

obsoleted the carburetor (~80s)

Advantages of EFI

Precise and accurate fuel measurement Improved cylinder-to-cylinder fuel

distribution (MPFI, GDI, DDI)

Predictable exhaust composition

Enables use of optimized catalytic

converters Net benefits

#1: Lower emissions

#2: Higher efficiency

#3: Increased power

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The ECU Control Loop

Throttle position

Intake air temperature

Manifold air pressure

Mass air flow (MAF)

Fuel pressure

In-cylinder pressure Coolant temperature

Crankshaft position

Camshaft position

Engine speed

Engine knocking

Exhaust gas oxygen

Fuel injection Idle speed control Ignition timing Multispark timing

Dwell angle

Valve timing (VVT) Camless valve actuation Exhaust gas recirc. (EGR) Turbo boost

Transmission control

PROCESS

CONTROL LOOPSSENSORS ACTUATORS

Engine Control Unit

(ECU)

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Mass Air Flow (MAF) Sensors

Source:

Air Flow Sensor - Key Device of A/F ratio control Engine

Engine Technology No.48 (February, 2007)

Sankaido Publishing Co., Ltd, Japan

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Environmental Effects

Source: NOAA

Global concentrations of major greenhouse gases

smog

internal combustion enginescontribute to CO2 and NOx

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Engine Management - Market Drivers

Source: CAS

0.00

0.10

0.20

0.30

0.40

EPA(US)

('83)

TLEV

(~'99)

LEV

(~'00)

ULEV

(~'04)

SULEV

(~'07)

HC (g/mile)

NOx (g/mile)

Source: Hitachi, Ltd., Automotive Systems Group

SULEV*Super Ultra Low Emiss ion Vehicle

Californ ia Air Resources Board (CARB) Ratings

US NHTSA Corporate Average Fuel Economy (CAFE)

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Reducing NOx in Lean-burn Engines

NOx adsorption Urea selective catalytic

(SCR) reduction

Source: Honda Motor

AdBlue is a regis tered trademark by Verband derAutomobi li ndustr ie (VDA) for AUS32 (Aqueous Urea Solution 32%)

Source: VDA

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Urea SCR needs strict control

Electronics used to:

Sense urea solution level in tank

Check quality and concentration

Inject known amount of ureaLow urea level warning

Engine shut-off

Source: Mitsui

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The ABS Principle

During emergency braking, ABS automatically cycles

tire slip around point of maximum braking efficiency

( ) ( )%100

_

__

speedVehicle

speedWheelspeedVehicle

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First ABS-like Automotive System

Sure-Brake System supplied by Bendix

for the 1971 Chrysler Imperial

First ABS supplied by Bosch for 1978 S-class Mercedes and BMW 7

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Two Generations of ABS

Source: Robert Bosch GmbH

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Electronic Brake-Force Distribution (EBD)

Braking causes a dynamic weight transfer to the frontwheels depending on: Vehicle construction / geometry

Deceleration

Consequence: rear wheels tend to lock first

EBD reduces rear pressure to avoid rear wheel locking Similar to mechanical brake proportioning valves

EBD bases rear wheel control on slip rather than pressure

Wheel control kicks in before ABS in the low-G region EBD events occur frequently and are transparent to the driver

ABS and EBD usually share the same hardware Brake proportioning valve is eliminated

Better braking performance independent of vehicle loading

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Traction Control Systems (TCS)

Limits torque applied to wheels to prevent spinning

Also known as Anti-Slip Regulation (ASR)

Usually shares the electro-hydraulic brake actuator andthe wheel speed sensors with the ABS

Methods to achieve traction control:

Brake one or more wheels

Retard or suppress spark to one or more cylinders

Reduce fuel supply to one or more cylinders

Close throttle (with drive-by-wire throttle) or sub-throttle

Actuate boost control solenoid in turbocharged engines Brake-only systems are simpler, but less functional

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A Complete ABS/TCS System

Source: LEXUS Technical Training Manual

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Electronic Stability Control (ESC)

Enhances stability through

asymmetric braking (yaw)

ESC may be required during

ABS, DRP or TCS events

Sensors collect information

Individual wheel speeds

Steering angle

Yaw rate

Lateral acceleration ECU runs algorithms to detect

and correct ESC events

Mercedes W-140 S-Class had

first complete ESC in 1995

Key precursors (no yaw rate):

Mitsubishi Diamante/Sigma 1990

BMW all model line in 1992

Source:II

HS

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Importance of ESC

High visibility after moose test by a Swedish car magazine in 1997

Today considered the most important safety feature since the seat belt,

studies show ESC reduces fatal car accidents by about 35%

National Highway Traffic Safety Administration (NHTSA) will require

ESC on all new light passenger vehicles in US by 2012

ABS will not be mandatory but usually comes for free with ESC

ChooseESC! educational campaign across Europe

United Nations working group for adopting ESC as a Global Technical

Regulation (GTR)

What ESC cannot do:

Improve tire traction characteristics (-slip curve)

Increase vehicle lateral acceleration capacity

Change any of the Laws of Physics

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ESC Systems Keep Evolving

Source: Continental Teves, Inc.

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Sensors and Actuators in ESC Control

Pressure

sensor

(wheels x4)

Wheel speed

sensor (x4)

Lateral

acceleration

sensor

Yaw Gyro

Sensor

Interface

ASIC

(PS)

Interface

ASIC

(LAS)

Interface

ASIC

(GS)

Sensor interface

ASIC

LDO

regulator

+- 150 mA

MCU

16 or 32-bit

+

software

Pressure sensor

(master cylinder)

Central

Braking fluid

Motor Driver

(FET)

DC

Motor

Solenoid

valve driver

(FET)

2/2

Valve

Steering

Wheel

Sensor

Interface

ASIC

(SWS)

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Advanced Braking Systems

Active Rollover Protection (ARP)

Extra gyroscopic sensor to monitor roll motion

AdvanceTrac with Roll Stability ControlTM (Ford)

Adaptive Cruise Control (ACC)

Sensors based on radar or LIDAR (laser) to measure distance

Brake Assist (BA or BAS)

Sensors to detect panic braking or that a collision is likely Possible actions: warn driver, pre-charge brakes with maximum

pressure, apply full braking automatically

Brake-by-wire

Eliminates traditional mechanical and hydraulic control systems

Uses sensors, electromechanical actuators and human-machine

interfaces, such as pedal and steering feel emulators

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A brake-by-wire system

Source: Reza Hoseinnezhad

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Sensors & SensorInterface

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Converting for Signal Processing

Signals to sense

Temperature

Force / PressureTorque

Rotation / Position

Level

Speed / AccelerationFlow

Acoustic

Magnetic field

RF

Light / Radiation

Chemical

Available electrical signals

Voltage

CurrentCharge

Resistance

Capacitance

Inductance

Impedance

Domains for processing

Analog

Digital

Mixed signal

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Sensing ASICs Requested by our Customers

voltageelectrochemicalO2 concentration

chargeMEMS tuning forkOrientation (gyro)

currentbiochemicalBlood glucose

voltageultrasonicDistance

resistancethermistorUrea concentration

currentultrasonicGas flow

charge

CsI scintillator +

photodetectorX-ray radiation

currentphotodiodeLight

capacitanceMEMS capacitorsAcceleration

inductance, resistancemagneticAngle / position

resistancethermistorAir flow

voltagepiezoresistive bridgePressure

Electr ical signalSensorPhysical quantity

Au

tomotive

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Process depends on Application

I3T50

I3T80

C035

ABX

VoltageVoltage

Gate CountGate Count1K 5K 100K 500K

100 V

80 V

50 V

25 V

5 V3.3 V1.8 V

HBIMOSI2T100

C3,C035UC07

FeaturesFeatures(OTP, EEPROM, etc.)(OTP, EEPROM, etc.)

C018

I2T30I3T25

>1.5 u 0.7 u 0.6 u 0.35 u 0.18 u Geometry(drawn poly)

D3C5X

I4T

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Automotive Protections

Overvoltage and reverse battery (OVRB) protections

Electrostatic discharge (HBM, MM, CDM)

Automotive transients:

AEC Q100 automotive standards

ISO 7637 pulses

Load dump

Schaffner pulses

Other local standards

Output shorted to battery or ground

Current sensing and limiting Over-temperature protection

less common insensor interface

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On-chip Overvoltage Protection

5 V supply with on-chip overvoltage / reverse batt protection

Solution covered by patents

At least 18 V protection allowed (process dependent)

Ext. +5V supply Int. ASIC supply

GND

Low voltage drop switch

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Passive Wheel Speed Sensors Wheel speed sinusoidal voltage

Both frequency and amplitude are

proportional to wheel speed

Noise-limited at low wheel speeds

NCV1124 (dual) and NCV7001(quad) generate square waveform

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Active Wheel Speed Sensors

Commonly based on Hall effect

Only frequency varies with speed

Can sense speed down to zero

Delivers a square current waveform

Sensitive to contamination by rust

or metal fillings

Other possible technologies:

Magnetoresistive (MR) and GiantMagnetoresistive (GMR)

Based on Eddy current

Optical sensing

Wiegand effect Sensor interface circuit depends on

the technology

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Wheel Speed Interface

Interface for Active and Passive Speed Sensors

Compact Digital/Analog tracking loop with ~1 MHz sampling

Programmable Hysteresis levels and filtering to increase noise robustness

Fast and slow tracking mode (1 DAC + 1 comparator per wheel)

=> Low cost and small size

Diagnostic for fail safe logic (short to battery or ground, open inputs)

Proven on silicon

Peak And Valley

Detection

[x] bits+

D

A

C

+/- [y] lsb

(Fast tracking)

Wheel SpeedOutput

Speed SensorOutputHysteresisvalue

Hysteresis

value

Delay Delay Delay Delay DelayAnalog/Digital interaction

for smallest size

Analog/Digital interaction

for smallest size

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Steering Angle Sensors

Different technologies are available

Optical

Potentiometric

Inductive Hall-effect

Magneto resistive

and others

Technologies and ICs may be usedin other angle or position applications

Pedal position

Throttle control

Headlamp control

Height/level regulation

Source: Bosch, Hella

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A MR Angle Sensor ASIC

Two magneto-resistive bridges are offset by 45o

90o signals (sine/cosine) are divided and arctangent gives the angle

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Longitudinal or Lateral Accelerometers

Not strictly required for ABS control

but increasingly present in more

recent ESC systems

Used as a sanity check for wheeland vehicle speed calculations

Lateral accelerometer used to

prevent artificially low speed

calculations Longitudinal accelerometer used in

4-wheel-drive vehicles where all

wheels can be mechanically coupled

Capacitive MEMS technologybecoming dominant

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Sensor Interface for Accelerometer

Analog

GND ref

Temperature

sensor

12b

D/A

PGA

Digital

filtersDSP

for TC

C/V

conv

PGAC/V

conv

MUX

Digital

filters

Buf

12b

D/A

Buf

Single module or IC can accommodate 1, 2, or 3-axis accelerometers

Each channel is calibrated for accuracy and temperature compensated

Outputs can be analog or digital

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Gyroscopic Sensors

Measures angular speed (rotation)

Initial automotive gyros derived from

military / aerospace products

Yaw rate (rotation around vertical axis)

is mandatory in ESC

Roll rate is a recent addition in some

rollover prevention systems

Pitch rate has no current automotiveapplication

Today MEMS-based solutions allow

compact and inexpensive gyros for

automotive applications

Source: Continental

ESC sensor cluster with gyro

and accelerometers

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Example: Systron Donner (BEI) GyroChip

Quartz Rate Sensor (QRS) proprietary technology

Coriolis effect: converts momentum of a vibrating object into a force Piezoelectric property of the quartz converts the Coriolis force into

electrical charge signals proportional to the angular rate

P S A t A li ti

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Pressure Sensor Auto Applications

MAP Manifold Absolute Pressure

TMAP Temperature Manifold Absolute Pressure

DMPS Differential Manifold Pressure Sensor

DPF Diesel Particulate Filter

DDI Diesel Direct Injection

GDI Gasoline Direct Injection

HCCI In-Cylinder Pressure (future)

ABS Anti-Lock Braking Systems

ESC Electronic Stability Control

P S I t f (E l )

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Pressure Sensor Interface (Example)

Nonlinear temperature compensationfor gain and offset

NVM d N li it C ti

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NVM and Nonlinearity Compensation

All sensing elements have nonlinearities (NL)

Intrinsic nonlinearity over sensing range

Offset & sensitivity NL variations over temperature

Market requirements for sensors with higher

accuracy and extended range

Trimpots / manual methods not viable for mass production

Laser trimming: expensive, requires special technologies LUT not always can provide enough accuracy

Solution: embedded programmablecompensation with NV memory

Solution: embedded programmablecompensation with NV memory

Our Proprietary Solution for NL

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Our Proprietary Solution for NL

Methods and circuits based on Pade Approximants, the ratio

between two power series

Accuracy and cost advantages when compared to

Lookup table (LUT)

Piecewise linear approach

Polynomial approximation (Taylor expansion series) Patents granted and pending worldwide

L

LL xpxpxppxP ++++= L2

210)(

MMM xqxqxqxQ ++++= L

2211)(

1)(

)()(

1

1

+

+==

cx

bax

xQ

xPxy

a 1st order PadApproximanta 1st order PadApproximant

Mapping a NL Function into a Linear one

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Mapping a NL Function into a Linear one

x2

Vin

Nonlinear input from

sensing element

x1

x

VoutCalibrated and

compensated output

x

v2

x0

vi1

vi0

vi2

v0

v1

x0

mapping

x2x1

VoutVinc

bVina=

+

+

1

=+

=+=+

2222

1111

0000

vvvicbvia

vvvicbvia

vvvicbvia

By applying Pad to Vin and replacing values at calibration points x0, x1, x2a system with 3 linear equations and 3 variables (a, b, c) is generated

By applying Pad to Vin and replacing values at calibration points x0, x1, x2a system with 3 linear equations and 3 variables (a, b, c) is generated

Two Practical Circuit Implementations

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Two Practical Circuit Implementations

G

D/A

OFFSET

REGISTER

+

+Vout

D/A

FEEDBACK

REGISTER

D/A

GAIN

REGISTER

Vin

_

voffG

kvf

Input signal

signal

compensated

for nonlinearity

G

D/A

OFFSET

REGISTER

+

+Vout

D/A

FEEDBACK

REGISTER

D/A

GAIN

REGISTER

Vin

_

Gvoff

G

kvf

The following transfer functions are realizedThe following transfer functions are realized

voffVinVoutkvfGVout += )1(

Isolating Vout, we verify both functions to be Pad ApproximantsIsolating Vout, we verify both functions to be Pad Approximants

1+

+=

VinkvfG

voffVinGVout

1

)(

+

+=

VinkvfG

voffVinGVout

voffGVinVoutkvfGVout += )1(

Application in NL Temperature Compensation

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Application in NL Temperature Compensation

Temperature compensation is a basic

building block in sensor interface

A temperature reference is neededeither internal or external to the IC

Applies temperature dependent

nonlinear offset and gain to the signal

path to cancel out the sensor

temperature dependency

Many possible implementations can

be realized

OFFSET DAC

REGISTER

OFFSET TC

COEFFIC.

A/D

D/A

T (dig)

a,b,c

TEMP

SENSOR

T

ALUGAIN TC

COEFFIC.

GAIN DAC

REGISTER

D/A

G+

+/-

VinVout

a,b,c

Methods for Temperature Compensation

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Methods for Temperature Compensation Error plot shows PWL has

greatest error

Pad and 4th order Taylor

series about the same error

But when implemented using

integer math (for RTL), the

Pad benefit is evident

Communication Embedded IVN

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Communication Embedded IVN

Integrate high voltage communication transceiver on chip LIN-Spec. 2.1 (SAEJ2602)

CAN-HS

CAN-LS K-Line (ISO9141)

SENT Single Edge Nibble Transmission

ON solution: excellent EMI performance, small area (patent pending)

Other standards (2-wire SENT, PSI5, etc)

BUS Phys.Layer ECU

BUS Phys.Layer

Upper

layer

SPIInterrupt

ECU

ASICASIC

Flexibility Higher integration

Released ProductsTransceivers

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Transceivers

ISO11898-3

CAN LS Transceiver (3.3V)AMIS41683CANN1RGAMIS-41683

Dual CAN HS TransceiverAMIS42700WCGA4RHAMIS-42700

LIN Transceiver with 3.3V VReg.NCV7420D23R2GNCV7420

LIN Transceiver with 5V VReg.NCV7420D25R2G

SW CANSee One PagerNCV7356

CAN LS Transceiver (5V)AMIS41682CANM1RGAMIS-41682

HS LP CAN Transceiver with Error DetectionNCV7341D21R2G

Improved HS LP CAN Transceiver

with Error Detection (>6KV)

NCV7341D20R2GNCV7341

HS LP CAN Transceiver

(Edge WakeUp - Matte Sn)

AMIS42665TJAA6RG

HS LP CAN Transceiver(Level WakeUp - NiPdAu)

AMIS42665TJAA3RL

ISO11898-5HS LP CAN Transceiver

(Level WakeUp - Matte Sn)

AMIS42665TJAA1RGAMIS-42665

CAN HS Transceiver (3.3V)AMIS30663CANG2RGAMIS-30663ISO11898-2CAN HS Transceiver (5V)AMIS30660CANH2RGAMIS-30660

Stand-alone LIN TransceiverNCV7321D10R2GNCV7321

LINv1.3/v2.1J2602

LIN TransceiverAMIS30600LINI1RGAMIS-30600StandardDescriptionOPN (T&R)WPN

Failsafe Logic Functions

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Failsafe Logic Functions

1. Between MCU and ASIC Checks that MCU and ASIC are not disconnected (watchdog)

Checks that software inside MCU is following proper sequence and issuing proper flags (no code

jumps)

Generate references for MCU (clock, voltage etc )

Monitor SPI activity from MCU2. ASIC related

Undervoltage / Overvoltage

Start-up check for proper working of failsafe logic

Monitor of critical functions (solenoid and motor)

Possibility to only connect supply for solenoid

and motor when MCU and ASIC agree

Failsafe logic: System FMEA

In case something goes wrong then disableABS functionsbut normal braking can still be performed by driver.

Micro-Controller

Reference

Generation

FSFlag

Watchdog

Critical function

monitor

ECU monitor

Under/over

voltage

Disable ABS

functions

ASIC

Failsafe logic

enable

Sensor Interface: Partial Redundant System

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Sensor Interface: Partial Redundant System

Two independent measurement channels on one die

Synchronicity check performed also inside the ASIC

Full Redundant Application

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Full Redundant Application

Safety is guaranteed by redundancy two ASICs can beused

Synchronicity between outputs is checked by ECU

LC

oscillator

InputMux

Analog

meas.

path

Digitalprocessing

Supporting

blocks

Analog

Driver

Failure

detections

Excitation

coil

Receiving

coils

ASIC A

Output A

LC

oscillator

Input

Mux

Analog

meas.

path

Digital

processing

Supporting

blocks

Analog

Driver

Failure

detections

Excitation

coil

Receiving

Rotor

Sensor

coils

ASIC B

Output B

Excitation

driver

Excitation

driver

Sensor

Sensor

Opportunities for Cost Reduction

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Opportunities for Cost Reduction

Advantage of digital communication using SENT protocol

One driver is sufficient to transmit data from both sensors

Several checks are performed to validate the received SENT frame Use of two external set of sensors with different output

signals

One measurement path inside the ASIC

Failure detections / calibrations / self tests

Final Diagram

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g

New proposed architecture uses one measurement path

Satisfying very high safety requirements

Highly cost effective

For More Information

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View the extensive portfolio of power management products from ON

Semiconductor at www.onsemi.com

View reference designs, design notes, and other material supporting

automotive applications at www.onsemi.com/automotive