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XYZ-axis accelerometers roll for mobile CE apps

Posted: 11 Jan 2007 ?? ?Print Version ?Bookmark and Share

Keywords:sensors? accelerometers? motion sensor? Freescale? MEMS?

Freescale Semiconductor has unveiled three highly sensitive XYZ-axis accelerometers for smart mobile devices. The MMA7360L, MMA7340L and MMA7330L triple-axis accelerometers provide motion-sensing solutions for CE devices that require fast response times, low current consumption, low-voltage operation and sleep mode in small-profile packages.

The MMA73x0L family features sensitivity from 1.5g to 12g with two g-select options of 1.5g and 16g. The MEMS sensors are designed to enable selectable sensitivity of 1.5g/6g for the MMA7360L, 3g/12g for the MMA7340L and 4g/16g for the MMA7330L. Freescale says the capability to select various heightened multi-axis sensitivities is essential to detect fall, tilt, motion, position, shock and vibration for multiple portable applications and functions.

However, the company has found that customers don't need all four g-select options that were introduced in previous products. "Customers basically only use twovery low g with high sensitivity and high-g with lower sensitivity. In this way they can get very accurate tilt readings but also have shock readings where none of the shock data is lost when getting the shock information. It allows them to have one g-select pin and set it at either high or low sensitivity through the MCU," explained Michelle Kelsey, marketing for accelerometers at Freescale.

Smaller packages
The MMA73x0L analog output sensors are housed in a 3-by-5-by-1mm LGA package that is 71 percent smaller in volume than the QFN package. "Because a lot of the products are thinner, they need a lower height so instead of using the stacked die configuration, we've gone back to the side-by-side to achieve the 1mm height," Kelsey said. Watch for lower profiles in next-generation introductions that target smaller consumer devices.

The MMA73x0L sensors feature low current consumption of 400?A, sleep mode at 3?A for extended battery life, and low-voltage operation at 2.2-3.6V. They also offer a fast power-up response time at 1ms and enable a response time of 0.5ms.

The low-g triple-axis accelerometer applications are suitable for mobile and 3D-gaming product user interfaces particularly with sensitivity to small changes in motion and tilt.

The heightened multi-axis sensitivity and full range of motion of the MMA73x0L sensors allow mobile and game users to make very small movements that are reflected in accurate responses when scrolling, flying, driving and executing other quick responses, said the company.

Damage protection
In addition, portable electronics products are protected against disk drive damage caused by accidentally dropping with the zero-g detection capability, which provides a logic interrupt signal when all three axes are at zero-g. The advanced motion sensing from these three-axis accelerometers detects when a device is falling and takes steps to prevent damage to sensitive electronics components.

The MMA73x0L sensors also provide enabling technology for anti-theft applications in laptop computers. An accelerometer within a laptop security system can be used to detect improper motion and trigger an audible alarm.

The low-g accelerometers currently are available with analog output, enabling a high degree of linearity for motion sensing applications. Digital output accelerometers are planned for introduction later in 2007. The sensors are RoHS-compliant.

Accelerometers from Freescale

The MMA7360L, MMA7340L and MMA7330L sensors are available now in sample quantities, with general availability expected Q2 2007. The suggested resale price in quantities of 10,000 starts at $3.66 for the MMA7360L, $3.59 for the MMA7340L and $3.53 for the MMA7330L. Suggested consumer product pricing is less than $2 in high volume.

Evaluation kits also are available for the MMA7360L, MMA7340L and MMA7330L sensors. The small circuit boards can be used to evaluate the devices to quickly develop prototypes. An external MCU, such as Freescale's 8-bit MC9S08QG8CDTE MCU, can be used in the end design. The kits (KIT3376MMA7360LE, KIT3376MMA7340LE and KIT3376MMA7330LE) are available at a suggested resale price of $35 each.

- Gina Roos
eeProductCenter




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