TPMS Presentation - NXP...

Sr.Auto FAE

Alan Yang (杨涛）

April 1 2014

TPMS Presentation

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F r e e s c a l e C o n f i d e n t i a l P r o p r i e t a r y

Alan Yang (杨涛）

TPMS 7*7 package Agenda

• Marketing trend

• How does TPMS module work in car

• Detailed specification of MPX87xx

• TPMS road map and comparison with the other supplier

• Our enablement resources

• Q&A

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• Q&A

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he Energy Efficient Solutions logo, mobileGT, PowerQUICC, QorIQ, StarCore and Symphony

are trademarks of Freescale Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack,

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of Freescale Semiconductor, Inc. All other product or service names are the property

of their respective owners. © 2011 Freescale Semiconductor, Inc.

Tire Pressure motivated by Auto mega trends

Mobility for everyone• TPMS is available for all type of

vehicles including truck and busses

• Scalable solutions• Multiple pressure ranges• Multiple rotation axis• Multiple RF frequencies

Cleaner world for everyone• TPMS allows optimum tire

inflation and thus fuel consumption and CO2 emission reduction

• Maximizes tire life• European and Korean legislation

driven by CO2 reduction

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Safety for everyone• Prevent roadside breakdown and

risk of road congestion• US tread act to prevent roll over

accidents• Future possibilities to link tire

information with chassis and ADAS system

Always Connected• Provides accurate tire data to the

driver• Filling assistant app on smart

phones• Fleets & Truck: enables better tire

management

TPMS legislation around the world

Region Requirements

USA Regulation from 2005: FMVSS138 mandates TPMS for new vehicles starting from October 1st 2005

European Union Regulation from 2012: EC661-2009 mandates TPMS starting Nov 2012 for new type approved vehicles and for all new vehicles starting from Nov 2014:TPMS will be tested as part of the new EU standardized plan for vehicle periodical inspection

S. Korea / Japan Regulation from 2013: TPMS vehicles to be installed on passenger cars from

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S. Korea / Japan Regulation from 2013: TPMS vehicles to be installed on passenger cars from January 2013 for new model and January 2015 for existing model

Russia, Kazakhstan, Belarus (Eurasia)

Valid from 2015 onwards & replaces nation legislation

Indonesia, Israel, Malaysia, Philippines, Turkey

Require European whole vehicle type approval for vehicles imported from Europe. As a consequence TPMS will be required for all new vehicles in November 2014

China Recommended specificationEnforcement Standard in Preparation

TPMS potential market size

• 100 Million new cars sold per year by the end of the decade

− 4 wheel per car + spare tires + winter tires

− Module Replacement market

• 1 billion cars on the road worldwide

− Great aftermarket opportunity

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Great aftermarket opportunity

− Great potential for tire mounted solutions

• Heavy trucks, busses, motorcycles

• Market outside of transportation requiring battery operated wireless pressure sensing

MPXY8700 Packaging

PcellGcell

MCU + RF

QFN 9 x 9 mmCavity Package(Cross Section)

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PcellGcell

Gel

Gel

Plastic flagLeadframe

Metal cap

Plastic housing

Plastic housing

Not to scale. For illustration purposes only.

Selective encapsualtion

(Cross Section)

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Tire Performance Issues

Aquaplaning (water depth >2 mm)Worsening until around 1.5 ba, then improvement due to bell formation of tread

centre inwards (at rated load)

General durability Reduced with lower pressures

Test Stand durabilityA reduction by 0.5 bar results in a worsening of 15 km/h in endurance (e.g.

Failure at 185 km/h instead of 200 km/h)

Resistance to curb impactA reduction by 0.5 bar results in damage sustained at 20% lower speed (e.g. at

40 km/h instead of 50 km/h)

Bead unseating from rimThe limit value for unseating of bead from rim lies between the operating

pressure and 1 to 1.2 bar. For safety reasons, this should never be lower

Wear A tire with 20% lower pressure has a running life around 30% less

Rolling Resistance A reduction by 0.5 bar results in an increase in rolling resistance of around 15%

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Rolling Resistance A reduction by 0.5 bar results in an increase in rolling resistance of around 15%

Tread NoiseA deviation of 1 bar from normal pressure (2 to 2.5 bar) worsens the noise level

by 2 dbA (66%).

Handling on dry and wet surfacesOn a mid-class car, an air pressure deviation of 0.2 bar from one axle is

noticeable.

(Source: Michelin Tires)

Tire Performance Issues

140

130

120

110

108

106

104

102

100

80

60

40

20

Serv

ice L

ife (

%)

Fuel U

se (

%)

Rolli

ng R

esis

tance (

%)

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1001012.0 1.7 1.4 1.1

0120 110 100 90 80 70 60 50 40 30

Tire Pressure (% of Specified) Tire Pressure (bars)

Decreased Tire Life withLower Pressure

Increased Fuel Use andRolling Resistance with

Lower Pressure

(Source: Continental Tires)

Pressure Accuracy

• Measurement accuracy target varies with OEM− Typical accuracies better than 8-10 kPa (1.2 – 1.4 psi)

− Typical resolutions of 1 to 2 kPa (0.15 – 0.30 psi)

• Accuracy over temperature, supply voltage and life of the tire/system

• Must warn based on the correct Cold Inflation Pressure (CIP)

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• Must warn based on the correct Cold Inflation Pressure (CIP) specified for the vehicle

• CIP limits usually set in the chassis receiver for a specific vehicle

Pressure Accuracy

• Effects of absolute vs. gauge pressure at altitude− In tire sensors measure absolute pressure

− Typical tire gages measure differential (gauge) pressurerelative to the atmosphere

• CIP is defined as the pressure of the tires afterthe has been stopped for at least 1 hour

• The “corrected” pressure using the Ideal Gas Lawis not used

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is not used− It is not the mass of air present setting tire performance

− It is pressure of the air that defines the load carrying capability and performance of the tire

• Generally accepted to use absolute pressure with a fixed atmospheric offset (approx 100 kPa = 14.5 psi)

TPMS System Solutions

• Direct (Measure Pressure in the Tire)− Use absolute pressure sensor inside the tire volume

− Communication via LF and/or RF links

− Mounted inside the tire/wheel

� On the wheel (valve stem or drop center)

� On the tire (side wall, bead area or tread belt)

− Powered by energy source

� Internal battery

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� Internal battery

� Source other than battery (battery-less)

• Indirect (Measuring Some Other Parameter)− Infer under-inflation by using parameter other than pressure sensing

� Wheel speed variations

� Ride height variations

� Tire vibration variations

− No power source required on the wheel/tire

Tire Pressure Monitor Systems: Indirect Measuring

• Implemented through ABS wheel speed sensors

• ABS system is able to measure individual wheel speed and compare it against other wheels

• If a wheel is moving faster, it is very likely it is under-inflated

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very likely it is under-inflated

http://www.aa1car.com/library/diagnosing_abs_wheels_speed_sensors.htm

≠

Tire Pressure Monitor Systems: Direct vs. Indirect

Direct Indirect

Precision ☺ �

Reaction time ☺ �

Detection of multiplefaults

☺ �

Position-dependantpressure warning

☺ �

Robustness under ☺ �

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Robustness under different driving conditions

☺ �

Number of additional components

� ☺

System cost � ☺

Required driver interaction

☺ �

Additional comfort features

☺ �

Tire Pressure Monitor Systems: Indirect Measuring

LikeLike

• Hardware reuse (ABS system)

• Cheap

Don’t likeDon’t like

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• Measurement relative to other tires

• Can only sense

• One under-inflated tire

• Three tires are under-inflated

• Two diagonally-positioned tires are under-inflated

• Will not work with under-inflated tires

• 2 on the same axle

• 2 on the same car side

• All 4

Direct TPMS Mounting Methods

Tire Wall Tire Tread Mount

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Drop Well MountValve Stem Mount

• Other Direct TPMS system features in the marketplace

−Display actual individual tire pressures

− “Tire Localization”determine location of tire on car

− “Auto-Learn”determine tire IDs on the car

TPMS Architectures

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determine tire IDs on the car

− “Initiation” triggering a pressure reading on demand

−Motion detection to change monitoring rates

−Motion detection to save battery power when parked

−Diagnostics for manufacturing and field service

Sensor Package Comparison

Freescale

MPXY87XX Competitor Freescale

MPXY85XX

/MPXY86XX

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• QFN 9x9x2.3mm

• PG-DSOSP-14-6• 9.24 X 11.09 X 3.9 mm

�MPXY85xx/86xx smaller in size will help on module’s size, weight and cost.

Top Level TPMS Model

Pressure

MotionSensor

3VBatt

LFReceiver

RFEnergy

Coil

LFSignal

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PressureSensor

TempSensor

Controller RFTransmitter

Ant Energy

Tire Pressure Monitoring Body Receiver

Antenna

RF

Stand along TPMS displayClusterInfotainment

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Stand along TPMS receiverOr RKE SystemOr PKE System

MCU &Control

RFReceiver LF

24 psi

MILBasicSystems

GeneralSystems

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• Microcontroller• S08 core, 0.25um SGF technology

• 16 kB SGF flash (8kB firmware, 8kB customer), 512B RAM, 64 parameter registers

• 10 bit ADC, temperature sensor and thermal restart

• 1-channel LF detector and decoder

• 8 MHz clock, 2-ch timer, 1 kHz LFO

• Integrated RF transmitter

• Frac-N PLL based transmitter, 315/434 MHz

• FSK/ASK modulation

• Manchester or bi-phase encoding

-1dBm to +8 dBm output power

512b

RAMRAM

LFRDetect and Decode16K FlashFlash

TPM2-ch

Register64 Bytes

10-bit ADCADC

BDM

LVD BG

Wakeup Timer

OSC 8 MHz

LFO 1 kHz

Temp Sensor

Temp Restart

UHF TX315 / 434 MHz C to V

Pressure Cell XZ-axis Accel

S08 Core

FXTH87xxxx6T1 Tire Pressure Monitoring System

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• -1dBm to +8 dBm output power

• Pressure Sensor• CMOS capacitive p-cell w/o signal conditioning

• Acceleration Sensor• Single XZ die

• Package• FAM 7x7mm QFN w/ gel fill

• Design Considerations:• RF Tx (7mA @ 5 dBm)

• LF Rx (4uA, snif)

• Process Technology – 0.25um

• Core Type – S08

• Voltage Supplies – 1.8V to 3.6V (transmit)

• Voltage Supplies – 2.3V to 3.6V (measure)

• Packaging Requirements – Media protection

Pressure Cell XZ-axis Accel

FXTH87xxxx6T1 Tire Pressure Monitoring System

Integrated Tire Pressure Monitoring System (TPMS) with smallest footprint (7mmx7mm) Integrated Tire Pressure Monitoring System (TPMS) with smallest footprint (7mmx7mm) lowest power consumption, largest customer memory size (8kB flash, 512byte RAM) lowest power consumption, largest customer memory size (8kB flash, 512byte RAM)

and unique dualand unique dual--axis accelerometer architectureaxis accelerometer architecture

• The compact 7 x 7 mm industry-leading package enables smallest module design for lighter weight

• Including an XZ-axis accelerometer offers customers motion detection and tire

• Robust package design with encapsulated inter-chip bond wires

Smallest Package Size Integrated XZ-Accelerometer Robustness / Power

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module design for lighter weight applications

• Same height as QFN 9x9 for smooth transition to QFN 7x7 solutions

• Highest degree of functional integration:

• Dual-axis accel, LF, RF, Pressure, MCU in one package

motion detection and tire localization capabilities

encapsulated inter-chip bond wires

• Storage temp: -50C / +150C

• Smallest RF transmit battery consumption

• 8kB of customer flash memory gives more application flexibility. Possible interface with external memory if required

• 512byte RAM

Troubleshooting: Typical Currents at ambient temperature

Normal OperationNormal OperationRF Behavior (To be

added to normal operation)

RF Behavior (To be added to normal

operation)RESETRESET BKGDBKGD

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RUN Mode2 mA

RUN Mode2 mA

STOP473 uA

STOP473 uA

STOP10.5uA

STOP10.5uA

RF ON Adder 77 uA

RF ON Adder 77 uA

RF Transmission

6mA

RF Transmission

6mA 1.2 mA1.2 mA 1.2 – 1.5 mA1.2 – 1.5 mA

Competitive Positioning & Value Proposition

• Customers cost benefit

− Smaller in size: 7mmx7mmx2.2mm

− Saving on board size , potting and housing materials.

− Saving on module weight (car OEM requirement)

− Boot Loader design allow uploading SW through LF – reduce cost of car OEMs call back cost by uploading SW at site.

− Auto-localization by using dual axis accelerometers.

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• Longer battery life

− 35% RF transmitting power consumption. <7mA at 5dBm

• Lower business risk

− Flash 8k space, 512 bytes RAM for customers

− 33% more space enabling a module suitable for more car models. (inventory/operation/ production management benefit).

− Improve cash flow for aftermarket tire shop by dual axis universal module and bigger memory size.

Lausitz: Significant Requirements - General

Characteristic Description

Data InterfacesLow Frequency Receiver

FrequencyModulationCarrier Sensitivity RangesData Sensitivity Ranges

RF TransmitterFrequencyModulationTransmit Power

125 kHzASK70 / 10, 14 / 2, & 3 / 0.5 mV ( Det / No Det

14 / 2 & 2.5 / 0.25 mV ( Det / No Det )

315 , 434 MHzASK, FSK5 dBm, 8dBm

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Package 7 x 7 mm 24 –Pin QFN

Physical Architecture – MCU HSC08 - SZK16 dedicated MCU

Physical Architecture – Pressure Transducer Capacitive cell with 100 up to 900 kPa range

Temperature sensor ∆VB sensor with -40 to +125°C range

Voltage Sensor Internal bandgap voltage reference

Physical Architecture – Z-Axis TransducerX-Axis Transducer

Teeter Totter ElementX-lateral Element

Lausitz and Nogaro Portfolio Under Development

Logical part number Device name (QFN 7x7)Operating Temp

range

P-cell range

(kPa)

Axis of

accelX-range Z-range

Nogaro FXTH8705026T1 -40C / + 125 C 100-450 Z NA -270g /+ 350g range with 40g sens

Nogaro FXTH870502DT1 -40C / + 125 C 100-450 Z NA -270g /+ 350g range with 40g sens

Lausitz FXTH8705116T1 -40C / + 125 C 100-450 XZ -70g/+80g range with 10g sens -210g/+240g range with 60g sens

Lausitz FXTH870511DT1 -40C / + 125 C 100-450 XZ -70g/+80g range with 10g sens -210g/+240g range with 60g sens

Nogaro FXTH8709026T1 -40C / + 125 C 100-900 Z NA -270g /+ 350g range with 40g sens

Nogaro FXTH870902DT1 -40C / + 125 C 100-900 Z NA -270g /+ 350g range with 40g sens

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Lausitz FXTH8709116T1 -40C / + 125 C 100-900 XZ -70g/+80g range with 10g sens -210g/+240g range with 60g sens

Lausitz FXTH870911DT1 -40C / + 125 C 100-900 XZ -70g/+80g range with 10g sens -210g/+240g range with 60g sens

Lausitz FXTH8709126T1 -40C / + 125 C 100-900 XZ -70g/+80g range with 10g sens -270g /+ 350g range with 40g sens

Lausitz FXTH870912DT1 -40C / + 125 C 100-900 XZ -70g/+80g range with 10g sens -270g /+ 350g range with 40g sens

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TPMS Roadmap

Tire Pressure Monitoring

MPXY85xx - Z-axis450/900 kPa

0.25uSGF, 2-Poly, 9x9 Cav QFN C90FGUHV IP Blocks

UMEMS Phs 4P C90FGUHV, UMEMS 4P, 5x5 FAM or CSP

U-TPMS XZ-axis450/900/1500 kPa

C90FGUHV, UMEMS-4P, 5x5 FAM or CSP

Nogaro Z axis450/900 kPa

0.25uSGF, 2 Poly, 7x7 FAM

Nogaro Z-axis450/900 kPa

0.25uSGF, 2-Poly, 7x7 FAM

Lausitz axis450/900 kPa

Lausitz XZ-axis450/900 kPa

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Lausitz axisUp kPa

0.25uSGF, 2 Poly, 7x7 FAM

Lausitz XZ-axisUp tp 1500 kPa

0.25uSGF, 2-Poly, 7x7 FAM

MPXY86xx - XZ-axis450/900 kPa

0.25uSGF, 2-Poly, 9x9 Cav QFN

Left Edge :

First Sample Date

Execution

Proposal

Planning

Production

Right Edge :

Product Qualification

Not resourced

2013 2014 20152Q 3Q 4Q1Q 2Q 3Q 4Q1Q 2Q 3Q 4Q1Q 2Q 3Q 4Q1Q

2016

450/900 kPa0.25uSGF, 2 Poly, 7x7 FAM

450/900 kPa0.25uSGF, 2-Poly, 7x7 FAM

Preliminary schedule. To be updated by August 31, 2013

Tire Pressure Monitor Sensor Roadmap Change-points

Gen2 Gen3 Gen4 Gen5

Package SOIC-20Bottom-side cavity;4-die

IntroduceQFN 9x9, Open top-side cavity;3-die

Introduce Film-Assist Mold QFN 7x73-die

Eliminate Die-to-Die Bond wires;2-die

ASIC Node

ASIC Design

TSMC 250nm SGF

Dedicated pressure & inertia interfaces( A/D & C/V )

TSMC 250nm SGF

Muxed C-V signal chains w/ Σ∆ ADC, digital filters;Up-integrate RF Tx

TSMC 250nm SGF

Muxed C-V signal chains w/ Σ∆ ADC, digital filters;Optimized LF/RF

Introduce 90nm TFS

Battery-less powerSystem ID, extended BIST, & selectable sensitivities

MEMS Nodes 2-poly inertia, 2-poly inertia & p-cell 2-poly inertia & p-cell Introduce eHARMEMS

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MEMS Nodes

MEMS Design

2-poly inertia,PIDR73 pressure

X-lat & teeter-totter;Redundant p-chip w/Integrated C-V

2-poly inertia & p-cell

X-lat & teeter-totter;Redundant p-cell

2-poly inertia & p-cell

X-lat & teeter-totter;Redundant p-cell

Introduce eHARMEMSfor pressure,eHARMEMS inertia

Combined Self Test + Sense

Test Physical @ probe & final

Physical @ probe & final

Physical / Electrostatic @ probe & final

Electrostatic @ probe & final

Certification &/orAssessment

AEC-Q100 AEC-Q100 AEC-Q100 AEC-Q100ASIL-QM, B target

Competitive Positioning & Value Proposition

• Smaller in size:

− Saving on board size (customer cost benefit)

− Saving on potting material (customer cost benefit)

− Saving on module weight (car OEM requirement)

• Flash 8k space for customers

− 33% more space enabling a module suitable for more car models. (inventory/operation/ production management benefit).

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production management benefit).

• Unique with dual-axis accelerometer

− enabling tire location determination without the need for user intervention and/or the use of LF initiator(s).

• Lower RF transmitting power consumption

− <7mA at 5dBm

• g-cells based on technology used in airbags we shipped close to1 billion unit level.

Power Consumption Comparison

CompetitorFreescale

MPXY8XXX

Operating Voltage

MCU, RF Transmitter1.9V to 3.6V 1.8V to 3.6V

Operating Voltage

Measurement 2.1V to 3.6V 2.3V to 3.6V

Stop Idd@ 25 °°°°C 0.7 uA 0.7 uA

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RF Output 5dBm @315MHz 3V 10 mA <7 mA

RF Output 5dBm @434MHz 3V 10 mA <7.6 mA

�MPXY85xx/86xx have lower RF transmitting power consumption will help on battery life and cost.

MCU Core Comparison

CompetitorFreescale

MPXY8XXX

MCU Core 8051 9S08

Flash for Customer 6K 8K

RAM 256 Byte 512 Byte

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�MPXY85xx/86xx with 8k flash for customers will allow one module for more car models by offering 33% more space for customers’ software.

�Benefit for customers’ inventory/production/operation management.

Sensor Performance Comparison

CompetitorFreescale

MPXY8XXX

Low Pressure Range

100-450 kPa

Maximum error

± 7 kPa0 ℃ to 50 ℃

± 7 kPa0 ℃ to 70 ℃

± 9 kPa0℃ to 70 ℃

± 10.5 kPa-20 ℃ to 85 ℃

± 17.5 kPa-40 ℃ to 125 ℃

± 16.8 kPa-40 ℃ to125 ℃

Medium Pressure Range

±10 kPa0 ℃ to 70 ℃

℃ ℃

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Medium Pressure Range

100-900 kPa

Maximum error

± 15 kPa-20 ℃ to 85 ℃

±24 kPa-40 ℃ to 125 ℃

Accelerometer Only Z-axis

Z-axisXZ-axis

No Accel

�MPXY85xx/MPXY86xx offer better temp performance enable better system accuracy.

Sensor Performance Comparison (continued)

CompetitorFreescale

MPXY8XXX

Max Operating Temperature -40 ℃ to 125 ℃ -40 ℃ to 125 ℃

Temperature Error

±3 ℃(-20 ℃ to 70 ℃)

±3 ℃(-35 ℃ to 70 ℃)

±5 ℃℃ ℃

±5 ℃℃ ℃

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±5 ℃(-40 ℃ to 125 ℃)

±5 ℃( -40 ℃ to 125 ℃)

Voltage Range 1.9V to 3.6V 1.8V to 3.6V

Voltage Error±100 mV

(-40 ℃ to 125 ℃)±75 mV

(-40 ℃ to 125 ℃)

Sensor Package Comparison

Freescale

MPXY87XX Competitor Freescale

MPXY85XX

/MPXY86XX

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• QFN 9x9x2.3mm

• PG-DSOSP-14-6• 9.24 X 11.09 X 3.9 mm

�MPXY85xx/86xx smaller in size will help on module’s size, weight and cost.

RF Basics�The transmitter generates a radio frequency (RF) signal

− OOK : The signal is canceled during low level

− FSK : The frequency of the wave varies with the value of the modulating signal

�The transmitter matching network optimize the transfer of power until the antenna

�The transmitter antenna transforms this RF signal to an electromagnetic wave

�The wave propagates to the receiver’s antenna

�The receiver antenna collects the wave at RF frequency

�The receiver matching network optimizes the transfer of power until the receiver input

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input

�The receiver processes the signal

TransmitterTransmitter ReceiverReceiver

Or FSKmodulation

Either OOKmodulation

TransmitMatchingNetwork

ReceiveMatchingNetwork

RF of TPMSWhat is impact RF receiving rate?

� RF Receiver design (RF antenna gain, device sensitivity, RF antenna matching, position & direction on car )

� RF emitter design (RF antenna gain, RF power, RF antenna matching, direction)

� RF protocol (FSK or ASK? Repeat times?)

RF Receiving Rate Power consumption Comment

FSK ☺ � FSK is less susceptible to interference

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interference

OOK � ☺ Lower cost for RF Receiver side and emitter side(Shrader)

Lower Baud Rate ☺ � It need to repeat the RF frame when the receiving rate can’t meet the target.Higher Baud Rate � ☺

Shorter Length of Protocol

☺ ☺

Higher RF power ☺ � It need to repeat the RF frame when the receiving rate can’t meet the target.

RF of TPMS

RF Frame Format

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RF Data Encoding�Manchester encoding (most customer)

� Customize encoding (S&T, TTE and etc.) NRZ encoding to resolve it!

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�Bi-phase encoding

Inter-Frame Spacing of RF

To avoid frame collisions between data from multiple sensors

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TPMS MCU power modes

Variable RUN STOP4 STOP1

Active clocks HFO,MFO,LFO

MFO,LFO

LFO

RAM (512 bytes) Active Stand-by Off

PARAM (64 bytes)

Active Active Active

RF Transmitter Optionally On Optionally On Optionally On

LF Receiver Optionally On Optionally On Optionally On

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LF Receiver Optionally On Optionally On Optionally On

Sensors Optionally On Optionally On Off

MCU On and clocking Stand-by, not clocking

Off

PWU ON ON ON

GPIOs ON Levels maintained

Hi-Z

Interrupts Optionally ON Optionally ON Some On, Someoff, will start code from main()

RSM RSM

TPMS RF Receiver

Direct TPMS Architecture (单向单向单向单向)

RSM

SPARE

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RSM: Remote Sensing Module

RSM RSM

Direct TPMS Architecture (双向双向双向双向)

RSM RSM

CA

N

TPMS RF Receiver

LFLF

LF LF

RSM

SPARE

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RSM: Remote Sensing ModuleLF: LF Initiator

RSM RSMC

AN LFLF

LF in TPMS SystemLF emitter in car OEM production line LF emitter in aftermarket

Automatic

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Automatic product line

Handheld tool

Handheld tool

Difference of LF Tool

LF on car (Dual way) Automatic product Line

Handheld LF emitter LF in bootloader

Trigger TPMS moduleSwitch the state (stationary, rolling, localization)

•Diagnostic (pressure, accel, battery, state) and record (ID, car module, date)

•Car model matching, tire position•Diagnostic (pressure, accel,

• Programming for different car model•Upgrade code

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localization) module, date) (pressure, accel, battery, state) and record (ID, car module, date)

•Upgrade code

40 – 90 cm ? 10 - 50 cm About 10 cm

Above 150 cm is not allowed




LF Receiver

• Amplitude• frequency• duration

Carrier Mode

Data Mode

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• Carrier Mode + Datagram in Manchester format

• Data Mode with no Manchester decoding• Used in rare cases

Direct Mode

LF Protocol�Standard LF telegram Manchester code (New TPMS system)

SYNC patterns

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� Special LF telegram (TPMS for replacement)

200 +/- 20 ms

20 +/- 2 ms 10 +/- 1 ms

Typical TPM Operational Parameters

Parameter Value Units

Data Measurement Interval

Motion

Parked

3

15

sec

minute

Data Transmission Interval

Motion

Parked

60

60

sec

minute

RF Transmission Protocol

Bit Rate 9600 bits/sec

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Bit Rate

Bits/Frame

Frames/Datagram

Pressure Change Alert

9600

90

4

256

bits/sec

bits

frames

frames

Diagnostic Modes 6 modes

Pressure Change Alert 15 kPa

Pressure Measure Range 100 to 900 kPa

Temperature Measure Range -40 to +125 °C

Example TPM Operational Profile

Moving (3650 hrs)

10 Years (87600 hrs)

25000 km/yrdecaying 1500 km/yr

Total Distance182500 km

4%

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Assume ConstantTemperature and Voltage

Parked (83950 hrs)

Average Speed of50 km/hr

Total Time Moving3650 hrs

96%

35%

10%

18%

Battery life and Power Consumption

Standby

Self Discharge

Reserve

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21%16%

ProcessingTransmit

Assume 250 mA-hr Battery205 mA-hr used (including self-discharge)

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Element Used for… Provided by MPXY8XXX

Absolute Pressure Sensor Acquiring tire pressure

Acceleration Sensor(s) Determining if the vehicle is moving deciding which wheel it is (MPXY86XX)

Battery Providing power to thesystem

Timer Deciding when to transmit

MPXY87XX/86XX/85XX

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Timer Deciding when to transmit

Control Unit (MCU) Gluing all actions together

RF Transmitter Sending data to the vehicle

LF Receiver Getting instructions from the outside world

Plastic/Metal housing Holding everything together

“Putting” Isolating electronic components from tire “goo”

Algorithm Perform actions systematically

Literature

• Data Sheet

− Describes Silicon

− FXTH87xxxx_rev0 3.pdf

• User Guide

− Describes Firmware

− FXTH87xx11_ug_213.pdf (2-axes

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− FXTH87xx11_ug_213.pdf (2-axes products)

− ngo_ug_294.pdf (1-axis products)

• Reference Manual/Application notes

− AN4277: Interfacing to firmware

− AN4391: LF design considerations

MPXY87XX/86XX/85XX : Freescale Firmware

• Physically, one 16Kbyte Flash block

• First half is empty

− 8kbyte for user

• Second half contains Freescale firmware

− Low-level drivers

− Math functions

Individual Trim/compensation

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− Individual Trim/compensation

− UniqueID

− CRC

− Interrupt vectors

MPXY87XX/86XX/85XX : Calling Freescale Firmware (1)

• MPXY87XX/86XX/85XX User Guide contains documentation for all in-flash firmware routines

• All routines can be called through an absolute-address pointer

Absolute Address Return Type Function

$E000 Void TPMS_RESET

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$E000 Void TPMS_RESET

$E003 UINT8 TPMS_READ_VOLTAGE

$E006 UINT8 TPMS_COMP_VOLTAGE

$E009 UINT8 TPMS_READ_TEMP

$E00C UINT8 TPMS_COMP_TEMP

… … Refer to User Guide for complete list


• The User Guide also contains a function definition

− For example, � UINT8 TPMS_READ_VOLTAGE(UINT16 *u16UUMA)

• Pointers to absolute addresses casted as pointers to functions can be declared for each firmware function

− For example,− #define TPMS_READ_VOLTAGE ((uint8_t(*)(uint16_t*))((uint16_t)0xE003))

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• Each pointer can then be treated as a regular C function

− For example,� u8Status = TPMS_READ_VOLTAGE(gau16UUMA);


• Interrupts are passed to the user directly unless owned by Freescale− ISRs owned by Freescale:� ADC

− ISRs flagged by Freescale before being passed to the user:� RFM

� KBI

� RTI

� PWU

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� PWU

� LVD

• User must declare pseudo-vectors and handle each interrupt as if it were its own

MPXY87XX/86XX/85XX : Other firmware functions

• Math− Checksum, CRC8, CRC16, 16-bit multiply,

− Square Root, Weighted average

• Measurements− Read analog voltage on PTA0, Read analog voltage on PTA1, Read

acceleration with dynamic offset loading

• RF− Calculate power dynamically, Read RF buffer, Reset RF configuration,

• Timing compensation

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• Timing compensation− Low-frequency clock compensation, Medium frequency clock compensation,

• Simulated SPI− Read, write

• LF Reception− Enable LF, decode data

• Flash− Write to flash, Erase flash page, Read UniqueID

Hardware: Schematic Example

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LF Receiver125 kHz

XTAL26 MHz

Matching (RF Emitter)315/434MHz

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Power-saving strategies

• Periodically call TPMS_READ_* routines, but only call TPMS_COMP_* routines if raw values have shifted significantly or if a long period of time has elapsed.

• When calling TPMS_COMP_PRESSURE or TPMS_COMP_ACCELERATION, reutilize existing voltage and temperature data instead of requesting new data

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temperature data instead of requesting new data

Measurement Uses

• Battery Voltage:

− Transmitted to car

− Helps unit determine EOL

• Temperature:

− Used to determine if device is Out Of Operation Range

• Pressure:

Transmitted to car

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− Transmitted to car

− Main function of the device – determine if tires are correctly inflated

• Accelerometer(s):

− Customer IP goes into different functionalities

Uses for acceleration

• Determine operation mode (parking/running)

• Determine wheel location

• Determine wheel position

• Determine thread’s wear

• ??

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TPMS_READ_ACCEL functionality

Zra

w (

counts

)

Threshold

Park Mode

Moving

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• TPMS_READ_ACCEL and TPMS_COMP_ACCEL are useful when trying to determine whether a vehicle is moving or is stopped

• i.e. Set a threshold, determine if the threshold has been passed – Car is moving

Time (s)

TPMS_READ_ACCEL functionality

Zra

w (

counts

)

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• TPMS_READ_ACCEL can also be used to determine position in the tire

• i.e. Each local maximum indicates top-most position in the tire, each local minimum indicates bottom-most position in the tire

Time (s)

TPMS_READ_ACCEL limitations

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• Assume 17-inch rim (diameter = 43.18 cm; radius = 21.59 cm)• Using centrifugal force formula

• Range, is +/- 33.9 km/h

Hardware: Layout (Silk Top)

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Hardware: Layout (Top Layer)

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Hardware: Layout (L2 GND)

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Hardware: Layout (L3 Power)

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Hardware: Layout (Bottom Layer)

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Hardware: Layout (Silk bottom)

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© 2014 Freescale Semiconductor, Inc.

www.Freescale.com

Date post:	06-Feb-2018
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