Melexis new PCB-free pressure sensor chip

Melexis, a global microelectronics engineering company, has released two relative pressure sensor chips with better robustness in harsh media. These two market-ready ultra-high-precision pressure sensor chips complete the Melexis PCB-free platform portfolio. With this series of pressure sensor chips, customers and OEMs will be able to make all their internal combustion engine management applications more environmentally friendly through a single modular technology. In order to further simplify the customer's production steps, this series of devices is factory calibrated, of course, customers can also recalibrate according to their needs.

MLX90823 (analog output) and MLX90825 (digital SENT output) are two relative pressure sensor chips that support gauge mode (corresponding to atmospheric pressure) or differential mode (with two variable pressure levels). Unlike absolute pressure sensor chips, they measure the pressure difference across the sensor chip. These factory calibrated devices are designed to measure pressure ranges ranging from 0.1 to 1.5 bar

These two new pressure sensor chips will bring the measurement accuracy of the automotive industry to a new level. Obtaining stable and accurate pressure and temperature data facilitates full life cycle management of the engine and can help OEMs reduce emissions from the last generation of internal combustion engine vehicles. The plug-and-play functionality supported by this family of pressure sensor chips from Melexis supports a wide range of internal combustion engine management applications. These include:

• Fuel Vapor and Crankcase Ventilation Applications: Ensures that fuel vapors in the fuel tank or gases leaking through the piston are brought back into the combustion chamber, preventing them from being vented into the atmosphere.
• EGR, GPF/DPF: Reduce nitrogen oxide emissions by sensing the amount of recirculated exhaust gas at the engine intake while trapping residual particulate matter in the exhaust filter.
• Secondary Air Injection (SAI): It allows rapid warm-up of the catalytic converter through "secondary air injection", so that vehicle emissions can be maintained within the limit value in various application scenarios (including cold engine start).
• (T)MAP: Monitors the air entering the engine and precisely adjusts the amount of fuel to reduce fuel consumption.

Both the MLX90823 and MLX90825 integrate sensors, signal processing circuits, digital hardware, voltage regulators, SENT or analog output drivers and all basic passive components. The MLX90825 supports pre-calibrated negative temperature coefficient (NTC) thermistor input (SENT output). Customers do not need to perform terminal calibration when connecting NTC through the pressure sensor chip. Excellent overvoltage (+40V) and reverse voltage (-40V) protection mechanisms are integrated in the chip. Thanks to the excellent coverage, this technology makes trucking more environmentally friendly. The operating temperature range of this series of pressure sensor chips is -40°C to 160°C, and can even withstand temperatures as high as 170°C for a short period of time, thereby supporting the trend of engine structure miniaturization.

The MEMS sensing element of the MLX90823 and MLX90825 consists of a micromechanical sensing membrane etched on a silicon substrate. The sensing membrane responds accordingly to pressure changes. Piezoresistive elements implanted in the sensing membrane are connected to form a Wheatstone bridge to generate the signal. The onboard front-end electronics then amplify the signal and convert it to digital. 16-bit digital signal processing (DSP) is responsible for temperature compensation. Finally, the result is provided via SENT output or analog output.

Both the MLX90823 and MLX90825 have been developed as a standalone Safety Element (SEooC) compliant with the ISO 26262 standard. MLX90825 (SENT output) can meet ASIL B level requirements, MLX90823 (analog output) can meet ASIL A level requirements.

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