Engine management and pneumatic seat system air pressure sensors

Infineon Technologies AG has introduced two new XENSIV barometric air pressure (BAP) sensors: the KP464 and KP466, targeted at automotive applications. While the KP464 is mainly intended for engine control management, the KP466 BAP sensor is designed for seat comfort functions.

The KP464 BAP sensor measures atmospheric pressure, which depends on altitude and weather conditions. The engine management system employs the sensor's measurement data to calculate the air density and provides the optimum air-fuel mixture. This is the key function for enhancing fuel efficiency and decreasing power consumption. With the lowered energy losses, emissions of CO2 and other pollutants can be minimised. The BAP sensor integrates density measurement with further diagnostics, such as manifold air pressure monitoring. Lower power consumption and extra package miniaturisation increase device productivity.

With the next generation of the KP466 BAP sensor, the company enables seat manufacturers to discover innovative pneumatic seat systems with many extra functions that are especially comfortable and deliver clear technical advantages. For example, the multi-contour seat function permits vehicle occupants to adapt the seat's contour to their personal needs. Air cells integrated into the lumbar support and seat cushion enable the seat to adapt to the body. Massage functions further improve passenger comfort on long journeys by alternately inflating and deflating the air cells. The driving dynamics function automatically alters the seat's side bolsters to the current driving situation, providing optimum stability for occupants, even when cornering.

The optimised solution consumes significantly less power and features a miniaturised five-hole housing. The system constantly monitors the pressure status and adjusts the pressure in the cushions according to the current requirements. It does this by using multiple absolute pressure sensors to monitor pressure throughout the system. The sensors are SPI enabled, enabling the system to communicate efficiently.

These sensors are high-performance, high-precision, miniaturised digital absolute pressure sensors based on the capacitive measurement principle. The sensors are qualified to the AEC-Q103-002 standard to meet automotive industry requirements. As a result, the devices decrease the effort and risk of errors during module and system qualification. They are micromachined on the surface and feature a monolithic integrated signal conditioning circuit. The devices convert a physical pressure into a 10-, 12- or 14-bit digital value and transmit the information via the SPI interface.

Also, these sensors can be integrated in a so-called daisy chain, which minimises the number of connection pins of the communicating microcontroller with any number of pressure sensors used. This is also feasible in combination with other of the company's system components.

Furthermore, a temperature sensor is integrated on the chips. Based on the received SPI command, the 10-, 12- or 14-bit temperature information is also transmitted via the SPI interface. The devices have a special power-down mode that lets the user reduce the power consumption of the sensors further. Also, the sensors integrate a diagnostic function that can be employed to test both the sensor cells and the signal path, improving the reliability of the devices. This diagnosis can be done automatically at sensor start and wake-up or triggered directly via an SPI command.