Accelerometer carries built-in noise filtering

Rohm Group company Kionix recently announced the availability of an accelerometer ideal for high accuracy, low power motion sensing applications in the industrial equipment and consumer wearable markets.

In recent years, as factories have begun to save labor costs and increase efficiency, the concept of predictive maintenance for detecting abnormalities before equipment malfunctions has gained broad acceptance. This has increased the need for machine health monitoring along using sensors to detect equipment conditions (i.e. motor vibration).

The KX134-1211 is a 3-axis accelerometer optimized for machine condition monitoring. Advanced Data Path (ADP) technology allows noise filtering and sensor signal processing normally carried out by the MCU to be performed by the accelerometer. They contribute to reducing MCU load and power consumption together with improved application performance.

In addition, to meet industrial requirements, the sensing frequency and acceleration detection ranges have been increased to 8,500Hz and ±64g, respectively, while supporting operating temperatures up to 105°C. At the same time, the sensor itself consumes less than half the current (0.67μA in low power mode) compared to conventional products. Additional features include Wake Up and Back to Sleep functions that contribute to lower power consumption, enabling sensing operation in battery-equipped wearable devices.

ADP is Kionix’s new function that replaces the filtering function of conventional MCUs. Specifically, multiple customizable frequency filters built into the sensor eliminate unnecessary noise signals by employing a versatile configuration that extracts only the necessary signals. Each filter can be switched ON and OFF, providing flexible operation. Frequency filtering and signal power calculation (root mean square calculation) conventionally carried out by a host MCU can now be performed on sensor side, reducing MCU load and associated power consumption.

The KX132-1211 features a max. frequency band of 4,200Hz and acceleration detection range from ±2g to ±16g, while the high-grade KX134-1211 expands the frequency band to 8,500Hz and acceleration range from ±8g to ±64g. In addition, unlike conventional products that can only operate up to 85°C, both models provide stable operation up to 105°C. The higher operating temperature supports a wider range of frequency and acceleration detection, making them ideal for machine condition monitoring such as motor vibration analysis in industrial equipment.

The KX134-1211 consumes 63% lower current than the current consumption of other conventional products (0.67μA in low power mode). In addition, a high resolution Wake Up function reports when acceleration exceeds an user-defined value. A Back to Sleep function prompts the MCU to switch back to an energy saving mode when acceleration is not detected for a certain amount of time. Reducing power consumption of not only the accelerometer but the MCU as well while the signal of interest is absent improves the power efficiency of the entire application, contributing to longer battery life in portable devices such as wearable and automotive smart keys.