Pressure sensors withstand harshest environmental conditions

December 11, 2014 // By Christoph Hammerschmidt
Measuring oil or hydaulics pressure in environments like a transmission or an internal combustion engine demands high thermal resilience and robustness. For exactly this kind of applications chipmaker Melexis has developed two pressure sensors. Besides the required thermal resilience they feature high sensitivity and strong linearity. Both exceed the automotive AEC-Q-100 requirements.

The MLX90815 and MLX90816 are implemented as  discrete micro-electro-mechanical (MEMS) devices for measuring absolute pressure in demanding operational environments. The MLX90815 is designed for optimal performance when determining pressures from 0 to 30 bar absolute, while the MLX90816 covers full scale pressures ranging from 30 bar to 50 bar absolute. Both have a maximum deviation in their linearity of just 0.2% FS. Typical sensitivity for the MLX90815 is 1.5mV/V/bar; for the MLX90816 it is 0.5mV/V/bar.

The sensor element incorporated into these MEMS devices consists of a piezo-resistive Wheatstone bridge connected to a micro-machined silicon pressure membrane, fabricated using Melexis' proprietary process technology. As pressure is applied to the membrane, a differential voltage change occurs across the outputs of the Wheatstone bridge while a bias voltage is applied to the bridge inputs.

The MLX90815 and MLX90816 pressure sensors can be supported by the company’s sensor interface chips (such as the MLX90320) in order to carry out output signal conditioning. These sensors are highly suited to a variety of automotive pressure monitoring applications, as well as industrial process controls, domestic appliances, medical equipment and consumer electronics gadgetry. Operating temperature range for both products is -40°C to +150°C.

These devices can be employed directly in conventional non-corrosive/non-aggressive media or incorporated into oil-filled sensor modules to further increase their robustness.

More information: www.melexis.com