Advanced sensor technology for next-generation temperature measurement

By combining high resolution and the ability to operate reliably in harsh environments, the MLX90640 infrared (IR) sensor array offers a cost-effective alternative to more expensive high-end thermal cameras.

This 32x24 pixel device is suited to safety and convenience applications that include fire prevention systems, smart buildings, intelligent lighting, IP/surveillance cameras, HVAC equipment and vehicle seat occupancy detection. It has a -40°C to 85°C operational temperature range and can measure object temperatures between -40°C and 300°C.

Also maintaining high levels of precision across its full measurement scale, the device delivers a typical target object temperature accuracy of 1°C. It exhibits superior noise performance, with a Noise Equivalent Temperature Difference (NETD) of just 0.1K RMS at a 1Hz refresh rate.

Unlike microbolometer alternatives, the sensor does not need frequent re-calibration, thus ensuring continuous monitoring and lowering system cost. Field-of-view (FoV) options comprise the standard 55x35° version and a 110x75° wide-angle version. The MLX90640 is supplied in a compact, 4-pin TO39 package incorporating the requisite optics. An I2C-compatible digital interface simplifies integration.

The MLX90342, simultaneously being announced by Melexis, is a quadruple thermocouple interface that provides rapid response with accuracy when measuring extreme temperatures. It has been specifically designed to allow automotive designers to address the need for more stringent engine and exhaust thermal management and control.

This need is being driven by the higher temperatures associated with new, smaller, more efficient engine designs. Target applications include turbo charger temperature control, Exhaust Gas Recirculation (EGR), Selective Catalytic Reduction (SCR), Diesel Oxidation Catalyst (DOC) and diesel/gasoline particle filtering systems.

The MLX90342 supports a -40°C to 1300°C thermocouple temperature range and has an operating temperature specification spanning -40°C to 155°C. Sophisticated on-board cold junction compensation and linearisation, plus factory calibration, guarantee an intrinsic accuracy of 5°C (at 1,100°C).

The sensor interface is housed in a miniature, 26-pin 6x4mm QFN package and has a rapid refresh rate of 50Hz that aligns with manufacturer expectations for high-speed response. Temperature data can be transmitted via a SENT Revision 3 digital interface, while extensive diagnostic capabilities monitor the health of the sensor and interface, identifying operational problems without the need for additional components. As a result, signal path integrity of data between the sensor and the engine management software is completely assured. Comprehensive integrated fault detection mechanisms also help sensor designs to conform to the latest vehicle exhaust regulations.

Sensor Business Unit Manager at Melexis, Damien Macq said: “As well as reinforcing our leadership position in temperature sensing, these two new devices provide further evidence of how inspired engineering can deliver real-world benefits to future applications that support safety, comfort and efficiency.”

Macq added: “As these new technologies illustrate, we have solutions that can address the broadest possible range of temperature sensing requirements, from the demanding performance and reliability needs of harsh, high-temperature automotive environments to the challenges associated with applications that require high-performance, high-quality sensing at competitive price points.”