Melexis integrated MEMs sensors handle more than just pressure

July 15, 2011 // By Christoph Hammerschmidt
The MLX90807 and MLX90808 fully integrated, relative and absolute pressure sensor die are realized with CMOS technology combined with MEMS bulk micromachining. These monolithic solutions are both fully automotive qualified. Each consists of a silicon membrane with piezoresistors to transform the stress induced by pressure into an electrical signal. An analog signal chain interacting with a digital core, including programmable memory, allows full calibration on chip in order to achieve an optimized transfer function over the desired working pressure and temperature range.

The Melexis integrated pressure sensor die cover many pressure ranges from a span of 100mbar to several bars. Their use is straightforward when the media to be measured is relatively benign like dry air found in barometric sensing or engine intake manifolds, brake boosters or even stronger media like fuel vapor. For harsher media applications like oils, liquids and engine exhaust gas, the Melexis chips must include special, secondary protection for the die.

The sensors are proven performers in demanding automotive applications. According to the vendor, the devices meet and exceed typical automotive industry quality standards. They are fully programmable through the connector with built in protection against all typical overvoltage automotive conditions. The integrated sensors include circuitry meet all automotive diagnostic requirements including broken membrane detection and short and open circuit conditions.

The applications and capabilities of these devices address several deficiencies found in competitive, integrated pressure sensors. Product Marketing Manager Laurent Otte indicates that “experimental data from stress testing shows the MLX 90807 and 90808 are capable of having the MEMs diaphragm cycled many times in excess of the standard test limits without failures”. Such results provide designers with a confidence level to allow use of the pressure sensors in high reliability applications knowing the chips can take the pressure. Secure too in the knowledge that in the unlikely event of failure the chip can communicate via diagnostics to allow for safe error handling.

For more information, contact brv@melexis.com.