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Dual-axis accelerometers deliver improved sensitivity for ESC systems

Austin, Tex. — Freescale Semiconductor has unveiled its advanced low-gravity (low-g) MMA6700/1EG accelerometers at this week's (Sept. 10) Freescale Technology Forum Japan. These dual-axis inertial sensors for electronic stability control (ESC) systems are designed to deliver more intelligence to automotive safety systems.

Key specs for the MMA6700 series include XY-axis of sensitivity in one device, 10- or 11-bit digital data output, and +/- 3.5 g or +/- 5 g full-scale range per axis. The series consists of the +/- 3.5 g MMA6700EG (11-bit data sensitivity = 3.43 mg/digit typical at 25°C) and the +/-5 g MMA6701EG (11-bit data sensitivity = 4.91 mg/digit typical at 25°C).

Leveraging Freescale's next-generation high aspect ratio micro-electromechanical systems (HARMEMS) technology, which features an advanced transducer design that delivers an over-damped mechanical response and a better signal-to-noise ratio, the MMA6700 devices deliver a much wider dynamic range and better sensitivity. Since the ESC system is installed either in the vehicle cabin or under the hood, over-damped HARMEMS technology enables a high degree of immunity to high-frequency, high-amplitude parasitic vibrations.

This means with the MMA6700/1EG accelerometers' wide dynamic range it enables ESC designers to filter out extraneous signals such as parasitic vibrations that could potentially interfere with the vehicle's lateral acceleration measurement, Freescale said. In addition, the accelerometers' integrated digital signal processor (DSP) provides higher accuracy and improves signal integrity for ESC applications.

For ESC applications, the higher signal-to-noise ratio combined with Freescale's DSP-based signal chain is designed to provide both a wide range and high sensitivity with less than one least significant bit (LSB) noise, Freescale said.

Operating from a 3.3-V or 5-V single supply, the MMA6700 devices provide a selection of integrated signal conditioning low-pass filters, support for signed or unsigned output data, and five customer-assigned, one-time-programmable (OTP) bytes. Other features include a SPI-compatible serial interface, a ratiometric analog voltage output and capture/hold input for system-wide synchronization support. It also supplies a bidirectional internal self-test and an on-chip temperature sensor and voltage regulator. The operating temperature range is -40°C to 125°C.

The low-g accelerometers, housed in a 20-pin SOIC wide-body RoHS-compliant package, can also be used in a variety of embedded applications that require measurement of small forces such as those resulting from shock, vibration, tilt, movement or acceleration. Applications include washing machines, sports medicine equipment, video game pads, seismic detectors and security systems.

Pricing: The suggested resale price starts at $7.67 for the MMA6700EG and the MMA6701EG in quantities of 10,000.
Availability: Samples of the MMA6700/1EG devices are available now to automotive customers. Volume production will begin in April 2009.
Product information: MMA6700 and low-g accelerometers

Freescale Semiconductor , www.freescale.com

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