Airbag Electronics: from Single Building Blocks to Integrated Solutions

Abstract

Airbag electronic systems measure various sensor signals and control several different actuators in an effort to prevent passenger injuries in case of accidents. This paper describes the electronics needed in such an application (acceleration sensors, bus interfaces, uC, power supply, squib drivers etc.) and the development of airbag systems as well as their increase of complexity over time. Acceleration information is delivered via PAS, PSI5 or DSI busses by high g acceleration sensors installed on vehicle corners and pressure sensors installed inside the doors. This information is validated by the microcontroller vs. centrally located inertial sensors. Precisely sampled acceleration values are used to identify a crash situation, in which case the firing circuit is enabled and a firing signal is sent to deploy the airbags. Building blocks like voltage regulator/power supplies and squib drivers have to provide the energy at the right time to ignite the airbag balloons mounted in the front and sides of the vehicle and tighten seat belts. Over time, new features have been added to the system - including rollover protection with airbag curtains, rear crash protection (whiplash prevention), and superior advanced crash detection algorithms to fire multi-stage airbags. All this functionality needs to be addressed by effective, safe, reliable, cost-effective electronics. Integration of the functions in a few application specific ICs and the fact that all function blocks and necessary semiconductor processes are available in one company makes the creation of synergies and the implementation of cost-effective silicon strategies possible.