The KP201 is a pressure sensor especially qualified for high temperatures up to 125°C, as they can occur in and around the engine compartment of a car in Pedestrian Protection Systems. In such a system, the pressure sensor is connected to a tube which is placed inside the front bumper of the car. When the tube is compressed by an object hit by the car, the KP201 provides a signal pulse which is proportional to the pressure change inside the tube (Δp/p0 ). The height of signal pulse is independent of the ambient pressure but is dependent on the relative pressure change. This is achieved by dividing the absolute pressure change by the ambient pressure. The division is performed on-chip.
The ambient pressure is calculated with a low pass filter from the absolute pressure. The sensor provides the relative pressure as a digital Manchester encoded output signal. This cost optimized configuration allows autonomous operation of the sensor without any further logic ICs in the pressure satellite. KP201 is also suitable for the detection of side impacts in passenger cars. In this application, the pressure sensor is assembled in a door module located within the car’s side door. During the normal operation mode there is a continuous internal range check