MEMS & Sensors

As people rely increasingly on technology to manage resources, control costs, protect the environment and enhance quality of life, this month’s Application Spotlight focusses on sensors as the vital link with the physical world.

Advances in sensor technologies are delivering savings in size, response time and cost, while also improving aspects such as reliability and noise immunity. The latest MEMS, Anisotropic Magnetoresistive (AMR) and CMOS-based sensors, for example, deliver chipsized devices such as the Freescale MMA7660FC three-axis MEMS accelerometer, Melexis MLX90609-N2 MEMS gyroscope, Murata AS-M15xx-R magnetic switches and National Semiconductor’s LM26LV combined temperature sensor and temperature-activated switch. The austriamicrosystems AS5145 magnetic sensor for noisy environments also joins Future’s selection of robust devices for motion, temperature, orientation, position and proximity detection.

There are three Design Notes offering valuable how-to information about MEMS and magnetic sensors. Engineers from austriamicrosystems and NXP Semiconductors explain magnetic sensing on pages 8 and 10 whilst, on page 13, Freescale Semiconductor describes how MEMS accelerometers combine with vibration analysis in new types of diagnostic systems.

Emerging optical and infrared sensors can be used to enhance comfort and convenience. The Vishay TEMD6200FX01 ambient-light sensor, in an 0805 case, is the closest yet to the human eye in terms of wavelength response, allowing engineers to fine-tune display or keypad backlights for optimum intensity under all ambient-lighting conditions. Touch-sensing innovations include a software-based touch controller from Freescale Semiconductor delivering dramatic savings in hardware costs. There are also several touch-based offers for members of the Future Electronics Board Club (www.my-boardclub.com), including a touch-controller board and a touch-sensitive LED-dimming demonstrator from Future Lighting Solutions.

Future Electronics' Sensors Solutions Guide

We are pleased to announce the release of our Sensors Solutions Guide, the first and most comprehensive sensors catalogue in the industry. To make component selection easier, the catalogue is organised by sensing technologies with introductory overviews, comprehensive product parametric tables and specific product highlights to showcase the most advanced and innovative products from our partners. To view online, or order a printed copy please visit:

www.my-boardclub.com/sensorcat.htm

Digital accelerometer supports adaptive, low-power motion-detection designs

With extra integrated functions, the Freescale MMA7660FC three-axis MEMS accelerometer allows designers to implement advanced user-interface features with minimal impact on power and size.

The MMA7660FC is a low-g digital capacitive sensor with a user-configurable output datarate, enabling easier system integration and power-saving design. Drawing only 47µA at 1sample/s, the device allows features such as orientation detection for handheld devices with minimal impact on battery life. The MMA7660FC also has configurable powersaving modes, which reduce current to 0.4µA in off mode or 2µA in standby mode, and include functions such as autowake/ sleep for precision power management.

Other intelligent features combine with the device’s external Interrupt pin to support adaptive gesture-based features such as tap- or shake-actuated commands. These can be used to control start/stop, scrolling, mute or other functions. The MMA7660FC also implements an I²C interface, which supports flexible communications and enables direct interfacing of sensor data to the main system processor.

With small dimensions of 3mm x 3mm x 0.9mm, the MMA7660FC enables engineers to build highly-featured user interfaces with negligible impact on PCB size. The accelerometer can also be used for image stabilisation, free-fall detection, anti-theft features, and auto-wake/auto-sleep triggering for ultra-energy-efficient products.

FEATURES


±1.5g full-scale range 120sample/s maximum output data-rate Supply-voltage range: 2.4V to 3.6V Digital I/O voltage range: 1.71V to 3.6V

APPLICATIONS


Cameras and security systems Handheld devices Rugged PCs Position controls

The MMA7660FC enables automatic features based on
orientation and motion, including portrait/landscape control.

Freescale / MMA7660FC