Integrated signal conditioning for a single-axis sensor was a remarkable achievement just a decade ago. Today, the level of signal conditioning has increased for multiple-axis sensing, and the packaging is even smaller. Three recently introduced products
for triaxial measurements demonstrate the improved capability for acceleration and angular-position sensors.
Analog Devices ADXL330 AccelerometerPrice: Less than $2.00 ea for high-volume consumer applicationshttp://rbi.ims.ca/4912-516 Within a mere 4 × 4-mm footprint (1.45 mm thick) in a 16-lead Leadframe Chip Scale Package (LFCSP), the ADXL330 houses a monolithic 3-axis accelerometer and the signal conditioning. The low power (200 µA at 2V) unit measures acceleration with a minimum full-scale range of ±2g. The accelerometer has a shock rating of 10,000g and features stable zero g bias, accurate sensitivity, and bandwidth adjustment with a single capacitor. Using the static acceleration of gravity, the accelerometer provides tilt sensing for motion detection in handheld products. Other measurement capabilities include dynamic acceleration resulting from motion, shock, or vibration. Target applications include mobile phones, media players, video games, cameras, and computers.
Melexis MLX90316 Hall Sensor Price: $2.57 ea for 5,000 (2,600 pieces per reel standard)http://rbi.ims.ca/4912-517 Using two pairs of planar Hall effect sensors with an integrated planar magnet, Melexis' MLX90316 can sense in three axes, however, the most common application is accurate measurement in two axes. The magnet provides a flux concentrator and shifts the input from perpendicular to planar for detection by the Hall sensors. A microcontroller (MCU) with a Digital Signal Processing (DSP) core computes high accuracy angular information from the sine and cosine signals from the Hall sensing elements and controls self-diagnostic and on-chip monitoring functions. The unit provides ratiometric and PWM analog outputs as well as a digital serial protocol output. An SOIC-8 houses a single die sensor or a fully-redundant design uses two isolated dies in a TSSOP-16 package. Target automotive applications include accelerator, brake pedal, throttle, and steering wheel position sensing.
Kionix KXP74 Tri-Axis AccelerometerPrice: $5.31 ea in quantities of 1,000http://rbi.ims.ca/4912-518 Measuring only 1.2 mm thick, the KXP74's 5 × 5-mm footprint dual-flat-no-lead (DFN) package contains a triaxial sensing element and separate application-specific integrated circuit. The sensor element has a hermetically sealed silicon cap applied at the wafer level to protect the mechanical structure. The digital accelerometer has user-definable sensor bandwidth and a Serial Peripheral Interface (SPI) for communicating with a host MCU or DSP. A noise specification as low as 70 µg per =Hz enables precision compass-tilt correction with minimal heading error. Factory-programmable sensitivity allows customization for applications in the ±1.5 to ±6.0g range. Target applications include consumer products, such as cell phones, MP3 players, PDAs, and micro hard drives.
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