Pressure sensors to revolutionise the world of MEMS

Melexis has launched the MLX90830, its first product to offer the new patented Triphibian technology. This exceptional miniaturised MEMS pressure sensor handles gas and liquid media measurement from 2 to 70 bar robustly. The factory-calibrated device measures the absolute pressure and supplies a proportional analog output signal. The device makes the module cost-effective by simplifying the system integration into the latest EV thermal management systems.

The company's ground-breaking Triphibian technology is core to the device, which allows the MEMS sensor to provide accurate measurements considerably above 5 bar and while in contact with liquid. This innovative combination of high-pressure sensing, while compatible with gas and liquid, is achieved by the unique construction of the device. The sensing mechanism comprises a suspended cantilever inside an SO16 package with the diaphragm at its tip.

The suspended cantilever design of the sensor supplies pressure spike immunity up to 2000 bar/msec and static burst level up to 210 bar. The two available calibrated ranges (10 or 35 bar) are each tailored to fulfil the demands of a distinct EV thermal management system, including low/high-pressure refrigeration loops. The device’s design is inherently more robust than rear-side exposed solutions, which still experience a pressure differential between the glass pedestal side and the wire bonding side. The pressure equalisation principle is also valid for frozen media, allowing the device to survive in such conditions, a first for MEMS pressure sensors.

Compared to existing non-MEMS-based designs, the device offers elevated accuracy and robust design, helping to optimise the efficiency of the vehicle’s thermal management systems, providing for a longer range. Also, its compact embedded packaging shrinks the sensor volume against standalone sensor modules.

The device includes a sensor readout circuit, digital hardware, voltage regulators, and analog output drivers. Piezo-resistive elements implanted into the membrane create a Wheatstone bridge to generate an output signal. This signal is amplified and converted into a digital format, allowing the 16-bit DSP to apply temperature compensation before providing the result as an analog output.

The sensor has advanced protective mechanisms against overvoltage (above +40V) and reverse voltage (below -40V). This makes it usable for truck applications. It has been developed as a SEooC under ISO 26262, enabling up to ASIL B system integration, ensuring it fulfils the latest EV safety demands.

"Access to miniaturised and accurate factory calibrated MEMS pressure sensors based on the Triphibian technology enable centralisation of thermal management systems in EVs, reducing the size and increasing the reliability of the system," states Karel Claesen, product manager Pressure Sensors. "The MLX90830 can easily be integrated by customers as a standalone device or embedded within the system."

"With the Triphibian technology, MEMS sensors can increase the pressure levels they measure while also expanding the type of media they face," explains Laurent Otte, senior product line manager. "Determining pressures of liquid media opens the door to applications both within the automotive industry and beyond, which historically could not be addressed by MEMS technologies."