Date: 22/10/2010

Inertial satellite sensors from Freescale for airbag safety systems

Freescale Semiconductor has added new members to its Xtrinsic line of intelligent sensing solutions specifically designed for enhanced automotive passenger safety. Freescale developed the MMA16xxW and MMA26xxW for airbag safety systems that use the widely adopted Distributed Systems Interface (DSI) 2.5 standard to connect remotely placed pressure, acceleration, occupant and buckle sensors to the main airbag electronic control unit (ECU). The DSI protocol supports point-to-point, parallel and daisy-chain networks. Pioneered by Freescale, Denso and TRW, the DSI protocol has been adopted by the world's leading manufacturers of supplemental restraint system (SRS) airbags.

"As advancements are made in vehicle safety design, the importance of sensors in the vehicle is growing," said Demetre Kondylis, vice president and general manager of Freescale's Sensor & Actuator Solutions Division. "By incorporating sensors into their designs, our automotive customers continue to bring to market vehicles with leading-edge safety features. Adding support for the DSI 2.5 protocol to our Xtrinsic line of sensors is one more way we're providing the automotive solutions our customers need."

Freescale says it is one of the only suppliers with both X- and Z-axis over-damped inertial satellite sensors housed in a quad flat no-lead (QFN) package, which provide a smaller footprint and more flexibility for module orientation in vehicles.

The Xtrinsic MMA16xxW and MMA26xxW sensors enable a 2 kHz or higher output data rate and up to four sensors on the same bus. The MMA26xxW also supports a bus switch, which enables the airbag system to reconfigure in case of satellite module failure to help ensure an always-connected safety environment.

Feature Summary:
±50 g to ±312.5 g, nominal full-scale range, X-axis, or Z-axis
Selectable 180 Hz, two pole, 400 Hz, four pole, or 800 Hz, four pole low-pass filter
DSI 2.5 compliant, with full support of mandatory commands
16 us internal sample rate, with interpolation to 1 us
-40 degrees C to +125 degrees C operating temperature range
QFN 6x6 mm 16-pin package
Qualified AEC-Q100, Revision G, Grade 1 (-40 degrees C to +125 degrees C)

Price and availability: Now starting at a starting price of $2.99 in 10,000-piece quantities.

Targeting automotive domain Freescale Semiconductor has also rolled out new SiP solutions that combine separate MCU and analog mixed-signal chips, fabricated in two separate processes, in a single package for automotive car body networks.

"With the availability of our S12-based SiP devices and the announcement of our new LL18 UHV technology, we're providing a powerful roadmap for our customers' automotive car body networks," said Ray Cornyn, director of Automotive Microcontroller Products for Freescale. "This new process technology will definitely push the limits of how we think about automotive body microcontrollers."

The MM912F634 family - the latest devices in Freescale's cost-effective S12-based intelligent distributed control (IDC) family of products, its features are:
Freescale's 16-bit S12 CPU with 32kb flash memory and 2k RAM;
An internal RC oscillator, two autonomous window watchdogs with dedicated oscillators and a real-time interrupt module;
Cascaded low-drop-out voltage regulators (5V and 2.5V) with fault detection and low-voltage reset (LVR) circuitry;
LIN 2.1 physical layer interface;
Two protected low-side outputs to drive inductive loads, two protected high-side outputs, six high-voltage inputs (shared digital and analog inputs, with wake-up capability);
Battery voltage sense with low-battery warning, reverse battery protection, configurable cyclic sense and a forced wake-up feature;
Current sense module with selectable gain;
Chip temperature sensor (readable via ADC channel);
Hall sensor supply implemented as switchable 18V voltage regulator;
Six digital (5V) general purpose input/output shared with SPI, three 5V digital/2.5V analog I/Os shared with 16-bit Timer, 2-channel PWM, 10-bit ADC and SCI with selectable pull-up resistor per terminal.

Price:
MM912F634 family: Suggested resale price of US$4.07 for 10K pieces

Availability:
MM912F634 family: Sampling now
LL18UHV: Expected to sample in early 2011, production quantities planned for mid-2012.