ADXL35x Series of Accelerometers
Analog Devices' ADXL35x series of accelerometers are designed for applications like structural health monitoring, or SHM, and orientation and navigation. The series is comprised of the ADXL354, which has an analog output, and the ADXL355, which has a 20-bit ADC and a SPI interface.
Now, there are a lot of accelerometers on the market today. So what makes these noteworthy? For this series, it’s their noise performance as well as their stability over time and temperature.
If you look at the accelerometers used in typical applications, like your smartphone, they lack the high combination of high resolution and ultra-low noise that allow you to measure your very small amplitude signals. They lack the stability and tight offsets offered by the ADXL35x series and required by applications like SHM and tilt sensing. They also lack the industrial-rated ceramic package and industrial temperature range that you need when you deploy to these applications.
Functional block diagram of the ADXL354
With SHM, your measurements are typically below five hertz and below half a g, and most accelerometers perform very poorly in those ranges. There have been studies done to determine whether smartphones could be used for SHM, and what they found was that you have up to a 50% amplitude error, and that highlights one of the key benefits of the ADXL35x.
Its noise density is spec’d at 25 μg/√Hz, which is four to five times lower than what you’ll find with consumer grade accelerometers. Noise density is a factor that basically sets a floor on the signal amplitude you can measure. In fact, with the ADXL35x can you measure below 1 mg at its full bandwidth, and you can measure even lower as you decrease your measurement bandwidth.
Functional block diagram of the ADXL355
Another key aspect for these applications is stability over time and temperature. The ADXL35x has a low zero-g offset of ±25 mg, and a low zero-g drift of ±3.5 mg, rated for 10 years. It also has a temperature sensitivity rating of 0.1%/°C. This means that, over the entire -40°C to +105°C temperature range, there will be very minimal measurement variation. There’s also a temperature sensor output on the device so you can correct for variation.
The devices also offer very low-power operation and standby modes, which are critical for battery-powered applications like inclinometers or wireless sensor networks used in SHM.
For more info, components, and eval boards for the Analog Devices ADXL35x-series accelerometers, visit Mouser.com.
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