Next-gen temperature measurement: Two examples from Melexis

November 10, 2016 // By Christoph Hammerschmidt
Measuring temperatures in applications with emphasis on safety, efficiency and convenience can become an easier task: Belgian fabless chip company Melexis has developed two new sensing technologies that promise to simplify the integration of temperature measurement into applications enhancing safety, efficiency and convenience.

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 32 x 24 pixel device is suited to safety and convenience applications including vehicle seat occupancy detection in cars, fire prevention systems, smart buildings, intelligent lighting, IP/surveillance cameras and HVAC equipment. It works under environmental temperatures between -40°C and 85°C and measures object temperatures between -40°C and 300°C. Maintaining high levels of precision across its full measurement scale, the device delivers a typical target object temperature accuracy of ±1°C. It also exhibits superior noise performance, with a noise equivalent temperature difference (NETD) of just 0.1K RMS at a 1Hz refresh rate. Unlike the conventional 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 55° x 35° version and a 110° x 75° 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.

Rapid response in temperature measurement:
The Melexis MLX90342

The other product also related to temperature measurement and announced simultaneously by the chipmaker, bears the type number MLX90342 and is a quadruple thermocouple interface that provides rapid response and very high levels of 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. Drawing on nearly three decades of automotive engineering experience, 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