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Advanced pressure sensor technology for
pressure based side airbag systems
Infineon
January 2003
Sunderland, 16.10.2003
Dr. Christian Burrer Infineon Technologies AG
Never stop thinking.
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Overview

• Business Unit Sense Control- Motivation
  Market View- Pressure Sensor Technology-
  System aspects - Optimised Chipset for pressure
  based Side-Airbag Systems- Summary

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Automotive Industrial Business Units
Automotive Industrial
Memory Products
Wireline Communications
Secure Mobile Solutions
Micro- controllers
Power Management Supply
Power Conversioneupec
Sense Control
Automotive Power
Business Focus - The Control of Power Powerful
real-time micro controllers, intelligent sensors
and power semiconductors
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Motivation for Pressure Based Side-Airbag Systems
New requirements High Bumper (IIHS) Pole
Impact (FMVSS201)
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Motivation for Pressure Based Side-Airbag Systems
Technical advantages Good differentiation
between fire-crashes and no-fire or misuse
cases Realization of quick-acting side airbag
systems possible (p-sensor 4... 6ms)
(g-sensors 810ms) Assembly place
inside the door is very flexible The same
pressure satellite can be used for various
vehicle types
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Motivation for Pressure Based Side-Airbag Systems
Side-Airbag Market TAM world-wide
Side Impact Airbags in mio. pcs
?
Year
Source SA 2002 PM IFX
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Surface Micromachining process flow
Wafer
BiCMOS Process Surface Micromachining
Boss
Cavity
On-Wafer Pressure Calibration
SMD Packaging
Pressure Calibration (parameter stored on-chip)
Testing
TapeReel
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Surface MEMS Capacitive Pressure Sensor
polyslicon diaphragm
pressure
passivation
boss
well
C(p)
sealed cavity
field oxide
substrate
sensor cell
field oxide pillars
passivation
field oxide
well
sealed cavity
Ccell 150 fF Sensitivity 5fF/bar Resolution (1
mbar) 5aF
substrate
reference cell
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Functional principle of the pressure sensorfor
side crash detection (New Generation)
1.)
1.) Capacitive Sensor array deflected due to
pressure
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System aspects of pressure based side-airbag
systems
KP100
Actual System
ECU
µC
Fire / no fire
airbag
Door module
fire decision in door module
pressure pulse
KP10x
Dp/p
New Generation
ECU
Door module
Fire / no fire
airbag
fire decision at ECU
pressure pulse
signal conditioning
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Optimised chipset for pressure based Side-Airbag
Systems
Safety
Program
Smart Crash
Controller
Memory
Sensor
(optional)
KP 10x
(on Chip)
C505
Squib
Smart Crash
Squib Driver (opt.)
Sensor 1
Squib
2 Channel
KP 10x
TLE 6712
Squib
Smart Crash
Squib Driver (opt.)
Squib
Sensor 2
4 Channel
KP 10x
Controller
TLE 6714
Sensor Interface
4 Channel
TLE 7719
C164
Smart Crash
Squib Driver
Sensor 3
2 Channel
KP 10x
TLE 6712
Smart Crash
Sensor 4
Squib Driver
KP 10x
4 Channel
Controller Supply
TLE 6714
Buck
Supervision
Communication
Sensor
Power Buffer
Reset, Watchdog
CAN, LIN
Supply
and
TLE 6711
TLE 6250,
Buck
Distribution
TLE42xx
Network
TLE 6287/89
TLE 6365
12V Rail
HS-CAN-Bus
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Summary

• Since 1997 expertise in pressure sensors for
  side-airbag systems (to date close to 10 Mio
  pcs are in the field)- Development of sensors
  for the new generation focuses on higher
  integration of logic- An optimised chipset for
  pressure based side-airbag systems was
  presented

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Backup.
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Optimised chipset for pressure based Side-Airbag
Systems
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Integrated Surface Micromachined Pressure Sensor
- KP 100
1. Sigma Delta Converter 4. Digital
Circuitry 2. Reference and bias generation 5.
Fuse array 3. Pressure Sensor Array 6. Bond-
and testpads
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KP 100 Signal Processing and Interface
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TLE 7719 (SatRIC) (Satellite Receive IC)
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Definition of the Pins
VCC
DTA-RDY
DTA-IN
DTA-OUT
CLK-IN
CLKS
GND
CS
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Selftest Functions
Digital DecimationFilter
????? Modulator
Sensor Membranes
µC
SPI

• Parity - Bit
• Parity-fuse Bit
• Diagnosis mode 1
• Diagnosis mode 2
• Diagnosis mode 3

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Parity - Bit and Addressing of Diagnosis Modes

• 15 Bit Parity
• ODD normal
• EVEN Diagnosis
• DTA_IN

0
1
...........
1
LSB
12 MSBs
Clock frequency
Diagnosis modes
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Typical Transfer Function
Y(p)a b?pc
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Technical Data