INTRODUCTION

Since the airbag was introduced its reliability and safeness has been improved continuously. A very important role comes up to the microcontroller that determines when to fire the airbag(s) based on sensor data.

COMPONENTS

Infineons 16-bit microcontroller C164CL/CG suits this application perfectly in combination with a micromachined acceleration sensor. The sensor provides measurement in two dimensions and including sensing, signal conditioning, system interface, and self-test capability.

Highly integrated power devices that reduce board space and pin count are dedicated to airbag applications. Application Specific ICs (ASICs) to fire and test the squibs are good examples. A power supply with step-down and step-up converters is fully integrated, too. This integration is possible due to Infineons smart power technologies combining bipolar, CMOS, and DMOS, on one chip. Infineon has already shipped more than 53 million System IC devices for airbag applications.

SCHEMATIC DIAGRAM of an airbag Electronic Control Unit (ECU):





SMD Pressure Sensor IC for Side Airbag Application
Specifically designed for Side Airbag Application, the KP100 is mounted in the doors of a car. It detects the pressure puls (compresed air volume in the door), created in the case of a crash.
The KP100 is fully calibrated and offset. It provides a Delta p/p Signal via a digital SPI Interface. Based on a capacitive measurement principle, this surface micromachined absolute pressure sensor communicates directly with a microcontroller, which also activates the sensors self-diagnosis function. Assembled in a 8-pin SMD package, cost effective automatic mounting on PCBs is guaranteed.
Features:

Digital output
Serial Peripheral Interface (SPI)
Offset calibrated
CMOS compatible surface micromachining
Diagnostic modes
Low cost
SMD housing