Electronic Design

MEMS Inclinometer Spawns Wide Application Range

When Analog Devices introduced its ADIS16209 dual-axis MEMS inclinometer and accelerometer as part of its iMEMS family late last year for industrial applications (“Tiny Dual-Axis MEMS Inclinometer Simplifies Industrial Measurements,” Nov. 15, 2007, p. 34; ED Online 17442), it became an instant hit. In fact, our readers called it the Best Leapfrog of the year. The ADIS16209 also won the Gold Best of Sensors Expo Award at Sensors Expo 2008, held in June in Rosemont, Ill.

Thanks to its intelligence, simplicity, and low cost, the sensor has spawned new products for many more industrial and medical applications, culminating with the four-degree-of-freedom ADIS16300 and six-degree-of-freedom ADIS16405 inertial management units (IMUs), unveiled last month at electronica 2008 in Munich, Germany.

“This part has been tremendously received and used in the industrial electronics arena and has formed the basis for a number of other iMEMS sensors that have penetrated not only industrial, but medical applications as well,” said Bob Scannell, business development manager for Analog Devices. “The distinguishing distinguishing feature in the ADIS16209 and other iMEMS sensors is their very ease of use, leading to a better and simpler user interface.”

The highly integrated ADIS16209 has broken new ground in price, performance, size, and ease of use. The dualmode inclinometer features dual-axis horizontal operation of ±90° and singleaxis vertical operation of ±180°. It operates from a 3.3-V power supply and provides a serial-peripheral interface (SPI) that enables simple integration into most industrial system designs (Fig. 1).

According to Analog Devices, it is the most accurate and easy-to-use tilt sensor on the market. It also is 100 times smaller than other available products at a price tag that’s one-tenth that of functionally equivalent competitive units. Its dimensions are a mere 9.2 by 9.2 by 3.9 mm, housed in a 16-terminal laminate-based land-grid array package. And, it operates from –40°C to 125°C.

Just how accurate is this sensor? It offers a fully compensated direct digital output with less than 0.1° of linear inclination error. It also features 14-bit digital inclination and acceleration data, with respective resolutions of 0.025° and 0.244 mg. Furthermore, it spans an acceleration measurement range of ±1.7 g. It provides a 12-bit digital temperature sensor output as well (see the table).

“We’re beginning to see a lot of medical applications for products like the ADIS16209 in ultrasound, mammography, and X-ray equipment to more precisely and accurately align the scanning procedure,” Scannell said. “We are also witnessing uses in hip and knee surgical procedures where accuracy is critical.”

The new IMU modules make it simple and affordable to implement sophisticated motion control and navigation control in a broader range of applications, including medical instrumentation. The ADIS16405 combines high performance, simplicity, and a tri-axis magnetometer sensor for improved heading accuracy (Fig. 2). The ADIS16300 is offered at an industry breakthrough price that is up to 10 times less than other competitive products.

Both devices offer similar performance specifications, though the ADIS16405 provides two more degrees of freedom. They feature a digital 14-bit gyroscope with digital range scaling, ±75°/s, ±150°/s, and ±300°/s settings, a tri-axis, 14-bit, ±5-g digital accelerometer (±3 g for the ADS16300), and 180-ms response time.

Additionally, they provide factory-calibrated sensitivity, bias and axial alignment, digitally controlled bias calibration, and a digitally controlled sampling rate up to 819.2 samples/s. (An external clock allows sampling up to 1200 samples/s.) They also boast digitally controlled filtering, programming condition monitoring, an auxiliary digital I/O, digitally activated self-test, and programmable power management.

These devices feature an embedded temperature sensor, an SPI-compatible serial interface, an auxiliary 12-bit analog-todigital converter (ADC) input and a digital-to-analog converter (DAC) output, and single-supply 4.75- to 5.25-V operation. They can withstand 2000 gs of shock and operate from –40°C to 125°C. The ADIS16405 has a tri-axis,14-bit, ±2-Gauss digital magnetometer, while theADIS16300 features 13-bit pitch and roll incline calculations and a 350-Hz bandwidth.

The ADIS16405 is 23 by 23 by 23 mm. It provides a flexible connector interface, which enables multiple mounting operation options. The ADIS16300 measures 23 by 31 by 7.5 mm and offers a standard connector interface, which enables horizontal or vertical mounting.

The pin-out for both is compatible with Analog Devices’ ADIS1635x family, allowing them to be dropped into sockets that use the ADIS1635x. The ADIS16405 requires minor firmware changes to accommodate scale-factor adjustments to take advantage of higher-performance features.

The ADIS16405 costs $412 each in 1000-unit lots. It is compatible with evaluation tools used for the iMEMS family of motion sensors. However, no specific board model number has been released. The ADIS16300 costs $74.00 each in 1000-unit lots. An evaluation board, the ADIS16300CBZ, is available. No price has been set for it yet.

Volume production for both the ADIS16405 and ADIS16300 is expected soon. The ADIS16209 is still priced about the same as when it first announced, going for $34.81 each in 1000-unit quantities. The ADIS16209PCBZ evaluation board, though, has dropped in price by nearly half to $95.00.

AnAlog Devices


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