Freescale rolls with automotive safety

R Colin Johnson

November 8, 2010

R Colin Johnson

KYOTO, Japan—Freescale Semiconductor unveiled new automotive sensor chips to meet consumer demand for increased safety and growing government regulations for better electronic stability and collision avoidance at Monday (Nov. 8) at Electronica 2010 in Munich, Germany.

Freescale's new chips include the company's first low-g accelerometer for stability control, plus new matched transmitter and receiver chips for the 77 GHz radars used for collision avoidance, according to the company.

In Europe, Asia and the U.S., growing legislative trends are mandating electronic control systems that grab both the wheel and the brakes from errant drivers' hands and feet to prevent catastrophic user-errors. Mandates include scheduled roll-out of adaptive cruise control, pre-crash impact mitigation, blind-spot detection, lane-departure as well as avoidance of normal fender-benders.

"Our smart Xtrinsic accelerometers reduce the space and cost of implementing advanced electronic stability control systems that meet or exceed the requirements of emerging new safety standards," said Dave Monk, automotive MEMS sensor operations manager at Freescale (Austin, Texas).

Freescale's new Xtrinsic MMA690xQ dual-axis low-g micro-electro-mechanical system (MEMS) sensor includes smart self-testing capability, which are automatically performed at startup, or can be activated under program control. An on-chip temperature sensor and digital-signal processor (DSP) also allows algorithms to continually insure that the accelerometer is accurately monitoring the momentum of the vehicle for use by electronic stability control systems.

The overdamped high-aspect-ratio micro-electro-mechanical system (HARMEMS) architecture and 6-by-6 millimeter quad flat no-lead (QFN) package raises the accelerometers resonant frequency to nearly 100-kHz, to insure that parasitic vibrations do not affect readings, according to Freescale.

The new accelerometers were designed for automotive electronic stability applications, but, at Electronica, Freescale will demonstrate the new sensors being used in a motorcycle airbag application. The vest-like airbag is worn normally until an accident, when the low-g MEMS chip senses motion that exceeds the bounds of normal riding and triggers inflation before the rider impacts the ground, other vehicles or stationary objects.


Freescale also debuted new transmitters and receivers for the 77 GHz radar band that aims to prevent accidents before they happen. Unlike conventional gallium-arsenide radar chips, Freescale uses silicon-germanium substitutes that come in at a much lower price, according to Freescale.

Using its 180 nanometer RF-BiCMOS process, which the company claims can handle high-frequency signals from 50-to-300 GHz, the new Xtrinsic radar chipsets were designed for adaptive cruise control, headway alert, collision warning, accident mitigation, blind spot detection, pre-crash braking and stop-and-go applications.

At Electronica, Freescale will be demonstrating its new chips in a rescue helicopter that uses forward-looking synthetic aperture radar (SAR) with beam forming.