Freescale Unveils Inertial Sensors with HARMEMS Tech for Auto Airbag Systems
November 24, 2008 // Published as a news service by IHS
Freescale Semiconductor introduced a family of inertial sensors targeted at enhancing the performance, sensitivity and reliability of next-generation automotive airbag systems.
The new medium- and high-acceleration (medium-g and high-g) accelerometers are engineered to detect a crash by measuring the abrupt deceleration of a vehicle and then triggering airbag deployment.
The Freescale MMA6222EG, MMA6255EG and MMA621010EG inertial sensors are based on next-generation high aspect ratio microelectromechanical systems (HARMEMS) technology.
MMA62xxEG product features include:
- XY-axis of sensitivity in one device.
- 10 b digital data output.
- ±20 g, ±50 g or ±100 g full-scale range per axis.
- Selection of integrated signal conditioning low-pass filters.
- First-order infinite impulse response (IIR) high-pass filter option.
- Serial peripheral interface (SPI) compatible serial interface.
- Bidirectional internal self-test.
- On-chip temperature sensor and voltage regulator.
- Support for signed or unsigned output data.
- Capture/hold input for systemwide synchronization support.
- 3.3 volt (V) or 5 V single supply operation.
- Ratiometric analog voltage output.
- Minimal external component requirements.
- Operating temperature range from -40 degrees Celsius to +105 degrees Celsius.
- 20-pin small-outline integrated circuit (SOIC) wide-body restriction of the use of certain hazardous substances (RoHS) compliant package
The company said the accelerometers' advanced transducer design enhances sensor offset performance and over-damping response, which improves system reliability and resistance to high-frequency and high-amplitude parasitic vibrations.
The devices are designed to distinguish airbag system conditions that might trigger a false deployment, such as a door slam or high vibrations during vehicle assembly.
The MMA62xxEG inertial sensors accommodate 3.3 V and 5 V supply voltage and offer developers the flexibility to use digital or analog outputs. The sensors also support bidirectional self-test and feature an SPI bus for enhanced monitoring capabilities.
Demand for airbag-related systems is driven by a combination of legislation, consumer influences and automotive growth in emerging markets, Freescale said.
"Safety system sensors follow powertrain as the second-largest sensor category in terms of market value, and safety sensor growth remains strong," said Mark Fitzgerald, an analyst at Strategy Analytics.
"Sensing for airbag systems is the largest application for automotive safety sensors in both unit volume and market value, and suppliers that offer competitively priced, reliable and high-performance inertial sensor solutions are well positioned in this market," he said.
Airbag distributed sensing systems can include two main engine control unit (ECU) inertial sensors and up to seven satellite sensor modules around the car perimeter for front and side impacts. The MMA62xxEG inertial sensors typically are included in the main ECU of the airbag application.
"As a leading automotive MEMS sensor supplier for more than 10 years, our design methodology integrates hardware and software by optimizing the partitioning between Freescale technology and our customers' intellectual property blocks for high-performance sensing solutions," said Demetre Kondylis, vice president and general manager of the Freescale sensor and actuator solutions division.
"Freescale's standard and customer-specific inertial sensors offer exceptional integration and system scalability as developers continue to cluster safety systems while maintaining a commitment to zero-defect quality," Kondylis said.
In addition to supporting automotive airbag applications, the MMA6222EG sensor can be used in applications that require measurement of small forces (±20 g) resulting from vibration or shock. Examples include:
- Preventive maintenance systems for industrial equipment in which an accelerometer monitors the frequency, amplitude and spectrum of the vibration signature to enable proactive machine health.
- Shock detection systems that assess a package's treatment during the shipping and handling process.
The following MMA62xxEG inertial sensors are available now:
- MMA6222AEG analog output trimmed, ±20 g.
- MMA6222EG digital output trimmed, ±20 g.
- MMA6255AEG analog output trimmed, ±50 g.
- MMA6255EG digital output trimmed, ±50 g.
- MMA621010AEG analog output trimmed, ±100 g.
- MMA621010EG digital output trimmed, ±100 g.
Source: Freescale Semiconductor Inc.