Melexis Triphibian revolutionises MEMS pressure sensors

The factory-calibrated device measures the absolute pressure and delivers a proportional analogue output signal. The MLX90830 makes the module cost-effective by simplifying the system integration into the latest electric vehicles (EVs) thermal management systems.

Core to the MLX90830 is the Melexis' ground-breaking Triphibian technology, which not only allows the MEMS (Micro-Electro-Mechanical System) sensor to provide accurate measurements considerably above 5 bar but also 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 MLX90830. The sensing mechanism contains a suspended cantilever inside of an SO16 package with the diaphragm at its tip.

The suspended cantilever design of the sensor provides 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 fulfill the demands of a distinct EV thermal management system, including low/high-pressure refrigeration loops. The MLX90830'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 MLX90830 to survive in such conditions, a first for MEMS pressure sensors.

Compared to existing non-MEMS-based designs, the MLX90830 provides elevated accuracy and robust design, helping to optimise the efficiency of the vehicle's thermal management systems, allowing for a longer range. Furthermore, its compact embedded packaging shrinks the sensor volume against standalone sensor modules.

The MLX90830 includes a sensor readout circuit, digital hardware, voltage regulators, and analogue 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 Digital Signal Processing (DSP) to apply temperature compensation before providing the result as an analogue output.

The sensor is equipped with advanced protective mechanisms against overvoltage (above +40 V) and reverse voltage (below -40 V). This makes it usable for truck applications. The MLX90830 has been developed as a Safety Element out of Context (SEooC) under ISO 26262, enabling up to ASIL B system integration ensuring it meets 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."