Condition-based monitoring (CbM) is a form of predictive maintenance that uses sensors to assess the status of equipment overtime while the equipment is operating. The collected sensor data can establish baseline trends, diagnose, or even predict failure. Utilizing CbM, maintenance is performed when needed as opposed to the conventional periodic preventive maintenance model, saving both time and money.

Vibration monitoring is a common type of CbM measurement because changes in vibration trends are potentially indicative of wear or other failure modes. To measure vibration data, high bandwidth (10kHz and more), ultralow noise (100µg/√Hz or lower) piezoelectric sensors were historically used to satisfy these requirements. The established sensor interface for piezo sensors is Integrated Electronics Piezo-Electric (IEPE), as a result, IEPE has become a de facto interface in the CbM vibration ecosystem.

With recent advancements in the microtechnology processes and fabrication techniques, MEMS accelerometers have caught up with piezoelectric sensors' low noise levels and supersede in other many specifications, such as DC to low-frequency response, thermal stability, shock resistance and recovery, and cost. The output of MEMS sensors, however, are either conventional 3-wire analog (ground, power, and signal) or digital if integrated with an ADC. Neither output is directly compatible with IEPE, the preferred CbM industry sensor interface.

This reference design enables a direct piezoelectric sensor IEPE replacement with benefits of high bandwidth, ultralow noise MEMS accelerometers. This circuit allows customers to easily evaluate the use of a MEMS accelerometer for CbM applications.