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DSI Airbag System

The central component of an airbag system is a control unit that combines a 16- or 32-bit MCU with a set of local acceleration sensors. Depending on the complexity of the system, additional satellite sensors provide supplementary crash information via a standardized sensor bus, such as the Distributed System Interface (DSI). Processed sensor data is used to fire front, side and curtain airbags with specialized multi-channel squib driver circuits.

As an additional safety factor, highly-efficient switched-mode power supply components allow the system to keep operating for several hundred milliseconds if the battery connection is lost during an accident.

Target Applications

Airbag System
Front Crash Detection
Rollover Sensing
Side Crash Detection

Featured Reference Designs

Airbag Reference Platform

Freescale DSI Airbag System block diagram

Recommended Solutions

Products	Features
Microcontrollers (MCU)
MPC560xP: Qorivva 32-bit MCU for Chassis and Safety Applications	Main MCU for sensor data processing, 32-bit MCU
S12GC: 16-Bit Microcontroller	Main MCU for sensor data processing
S12XE: 16-Bit Automotive Microcontroller	Main MCU for sensor data processing, 16-bit MCU
Watchdog Microcontrollers (MCU)
S12XF: 16-Bit Automotive Microcontroller	Safing MCU, 16-Bit MCU with up to 512K Flash for redundancy and watchdog functions
S12XS: 16-Bit Automotive Microcontroller	Safing MCU, 16-Bit MCU with up to 256K Flash for redundancy and watchdog functions
S12P: 16-Bit Microcontroller	Safing MCU, 16-bit MCU with 128K Flash for redundancy and watchdog functions
S08SG: 8-bit Small Package SG MCUs	Safing MCU, 8-bit MCU with up to 32K Flash for redundancy and watchdog functions
S08SL: 8-bit EEPROM with LIN S08EL and S08SL MCUs	Safing MCU, 8-bit MCU with up to 16K Flash for redundancy and watchdog functions
DSI Satellite Sensor Interface
MC33780: Dual DBUS Master with Differential Drive and Frequency Spreading	DSI 2-Channel Bus Master with Differential Drive
MC33781: Quad DSI 2.02 Master with Differential Drive and Frequency Spreading	DSI 4-Channel Bus Master with Differential Drive
MC33784: DSI 2.02 Sensor Interface	DSI Slave Device for remote sensing
MC33790: Two Channel DSI Physical Interface for Bus Masters	2-Channel DSI Physical Interface for Bus Masters
MC33793: DSI Slave for Remote Sensing	DSI Slave Device for remote sensing
CAN Interface
MC33897: Single-Wire Can Transceiver	Single-Wire CAN Physical Interface
MC33660: ISO K Line Serial Link Interface	ISO K Line Serial Link Interface
LIN / K Line Interface
MC33661: LIN Enhanced Physical Interface	LIN Physical Interface
MC33662: LIN 2.1 / SAEJ2602-2, LIN Physical Layer	LIN 2.1/SAEJ2605-2, LIN Physical Interface
Local Sensors
MMA2201: Acceleration Sensor	Main ECU Analog Low g Accelerometers, X-Axis
MMA3201: Acceleration Sensor	Main ECU Analog Accelerometers, XY-Axis
MMA62xx: Digital or Analog 2-Axis Micromachined Accelerometer	Main ECU Digital or Analog XY-Axis Acceleromters, SPI compatible
MMA65xx: Xtrinsic Dual Axis SPI Inertial Sensor	Main ECU X- and XY-Axis Inertial Sensors with arming functions for each axis, SPI compatible
MMA68xxKW: Dual Axis SPI Xtrinsic Airbag Sensor	Main ECU Dual Axis Inertial Sensors with arming pin, SPI compatible
Rollover Sensors
MMA1250EG: Acceleration Sensor	Analog Low g Accelerometers, Z-Axis
Squib Driver Four Channels
MC33797: Four Channel Squib Driver IC	4-Channel Squib Driver IC with complete squib diagnostic and deployment interface
Crash Satellite Sensor
MMA1250EG: Acceleration Sensor	Analog Inertial Satellite Sensors, X-Axis sensitivity
MMA2301: Acceleration Sensor	Analog Inertial Satellite Sensors, Z-Axis sensitivity
MMA16xx: Xtrinsic DSI Inertial Sensor	Xtrinsic Inertial Satellite Sensors, Z-Axis overdamped, DSI 2.5
MMA26xx: Xtrinsic DSI Inertial Sensor	Xtrinsic Inertial Satellite Sensors, X-Axis overdamped, DSI 2.5
MMA8XXXEG: Digital X-Axis or Z-Axis Accelerometer	Xtrinsic Satellite Acceleration Sensors, Digital X-Axis or Z-Axis, DSI 2.02

Advantages

Complete chipset targeted at airbag systems that are based on DSI standard delivers cost savings, scalability, and decreased time to market
Innovative MEMS-based satellite sensors and interial sensors designed for use as main crash sensor or safing sensor allow for improved performance and reduced overhead
Scalable Qorivva 32-bit MCU family for safety applications, up to 512 KB Flash, separate Data Flash, all with Error Correction Code (ECC)
Intelligent sensing technologies for front and side crash detection
Xtrinsic X- and Z-axis over-damped inertial satellite sensors housed in a QFN package provide a smaller footprint and more flexibility for module orientation in vehicles
Over-damped MEMS transducer and high resonance frequency package provide better immunity to overload conditions induced by high magnitude and frequency shocks
Improved system reliability against parasitc vibrations due to Freescale's overdamped MEMS transducer
Our Xtrinsic MMA16xx and MMA26xx satellite sensors, and the Qorivva MPC560xP MCUs are SafeAssure functional safety solutions
Broad portoflio of 8- and 16-bit MCU for redundancy and safing functions
Freescale product longevity program offers up to 15-year availability for selected product