MEMS to be used in pressure sensing applications

Applying its proprietary Micro-Electro-Mechanical System (MEMS) technology to an area that had not been previously adequately served by a fully integrated sensor solution means that major system design benefits can now be derived.

Available as a bare die, the MLX90819 runs off a standard 5V supply. It can be employed to accurately determine fluid pressure levels in wide variety of automotive and industrial focused applications. These include the monitoring of engine oil, transmission oil, engine coolant, vehicle fuel lines, air conditioning refrigerant and truck air brake pressures, just to mention a few. The IC delivers a relative pressure value. It has a 1ms response time, plus ±2.5% over life accuracy and ±0.2% linearity across its entire operational pressure range.

By using a more advanced process technology, the MLX90819 is unique in being able to leverage a microcontroller based architecture. This allows a much higher degree of sophistication to be incorporated onto the semiconductor die - with all digital processing, data conversion, temperature offset, gain compensation and filtering tasks being taken care of directly. A 16-bit analog-to-digital converter (ADC), 12-bit digital-to-analog (DAC) and high performance 16-bit processor core are embedded directly into each sensor IC. The cost and complexity implications of discrete MEMS solutions, as well as the space utilisation and sealing wear-and-tear issues that blight traditional non-MEMS solutions, can thereby be avoided. The IC can deliver either an analogue signal or a Single Edge Nibble Transmission (SENT) output for applications requiring a digital output.

This robust IC is highly suited to both heavy duty industrial and automotive deployment, with full AECQ100 compliance and a specified temperature range of -40 to 150°C. An automotive over-voltage protection mechanism is included in order to ensure ongoing reliability. An array of diagnostic features further support its long term operational integrity. These include analogue output clamping level and broken track detection, plus numerous distinctive diagnostic messages passed via the SENT protocol (such as internal temperature or pressure errors, external over-voltage/under-voltage conditions, etc.) The MLX90819 sensor ICs will be shipped in a die-on-foil format.

“This new approach to mid-range pressure measurement will clearly be appealing to engineering teams, as it presents them with the sensor technology they need to reduce test/assembly effort, lower component counts and save valuable space,” commented Laurent Otte, Product Line Manager for Pressure Sensors at Melexis. “The streamlined nature of the MLX90819 greatly facilitates the sensor system’s mechanical integration into customers’ modules, as only a PCB with a limited number of external components will be required. There is thus considerable potential to scale down the dimensions of the module into which it is housed.”