Interface IC simplifies thermocouple temperature sensing

November 12, 2016 // By Graham Prophet
Melexis' MLX90342 is a high-performance quadruple thermocouple interface that provides rapid response and very high levels of accuracy when measuring extreme temperatures. Melexis says it is responding to requirements, notably from the automotive sector, to simplify the use of thermocouple sensors with a multi-channel device.

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 linearization, plus factory calibration, guarantee an intrinsic accuracy of ±5°C (at 1100°C). This effectively means the sensor is twice as accurate as other currently available devices. The sensor interface is housed in a miniature, 26-pin 6mm x 4mm QFN package and has a rapid refresh rate of 50Hz that aligns with manufacturer expectations for high-speed response.

The part 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.

Temperature data can be transmitted via a SENT Revision 3 digital interface, while 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.