The most accurate automotive pressure sensor currently available

23-11-2022 | Melexis | Semiconductors

Melexis has released a new series of PCB-less pressure sensor ICs that provide the highest degree of accuracy over a lifetime. Thanks to this excellent performance, the last generation of ICEs will become greener in all cases.

This new series of integrated pressure sensors are targeting usage in automotive engine management. The MLX90824 determines the absolute pressure and then provides a digital output signal using the SENT protocol, whereas the brother product MLX90822 supplies an analog output voltage. These factory-calibrated devices measure pressure spans from 1 bar to 4 bar.

Laurent Otte, senior product line manager, explains why these sensors help Melexis customers: “An accuracy of +/-0.5%FS (full scale) is maintained over the course of the sensor’s working lifespan. This accuracy is not impacted by the sensor integration thanks to the PCB-less packaging“. Very accurate and stable pressure measurements allow optimal engine management to guarantee fuel savings and emission reductions.

The devices comprise a sensor readout circuit, digital hardware, voltage regulators and SENT or analog output drivers, and all the necessary passive components. A pre-calibrated NTC thermistor input is provided for the MLX90824 (SENT output). This enables customers to interface their NTC via the pressure sensor without end-calibration. Superior overvoltage (+40V) and reverse voltage (-40V) protection mechanisms are included. Thanks to this protection range, trucks benefit from this technology to become greener. These pressure sensors provide an operating temperature range from -40C to 160C. They can even be exposed to 170C temperatures for a short period, supporting downsized engine architectures.

The MEMS sensing element of the devices comprise a micro-machined diaphragm. It is bonded around a cavity etched into a silicon substrate and includes a reference vacuum. The diaphragm responds to any change in the ambient absolute pressure. Piezo-resistive elements implanted into the diaphragm are configured to produce a Wheatstone bridge that creates a signal. The accompanying front-end electronics subsequently amplify the signal and convert it into a digital format. The 16-bit DSP undertakes temperature compensation. Finally, the result is delivered through a SENT or analog output.

They have been developed as a SEooC in accordance with ISO 26262. It support ASIL B system integration for the MLX90824 and ASIL A for the MLX90822.

“Access to stable and accurate data on pressure as well as temperature enable long-term engine management across the full lifetime of vehicles. This positively influences fuel saving and emission reductions,” states Karel Claesen, product manager pressure sensors. “The MLX90824 and MLX90822 are optimised for the latest engine designs and their new operating conditions.”

For motorcycles or any equipment with small engines, including chainsaws, lawn mowers, amongst others, it is crucial to have a very fast update rate and step response sensor. The MLX90822 meets that demand with an output step response three times faster than any other pressure sensor made by the company.