Application Note: Conducted Transients In Road Vehicles' Supply Lines

Over the last thirty years, the number of electrical/electronic modules used in road vehicles has increased dramatically. The modules are used in many diverse functions, including engine and transmission control, comfort and entertainment functions (radio, air conditioner and heater) and critical safety features (anti-lock brakes and air bag systems). All of the electrical and electronic systems must operate without interfering with each other and without reaction to outside interference signals. The road vehicle is subjected to radiated RF signals as well as onboard radiating signals of its own. In addition, the vehicles electrical system generates transients that are conducted via the power lines to the electrical/electronic modules connected to it. This note explains the transients that are conducted via the vehicle power system and the means by which the electrical/electronic modules are tested for immunity to the conducted transients.