Modeling of Automotive Bus Transceivers and ESD Protection Circuits for Immunity Simulations of Extended Networks

To establish a stable communication between electronic control units in vehicles special bus systems were developed. CAN and FlexRay are safe data buses with high immunity against electromagnetic disturbances. To ensure the safety, the systems should be qualified with special RF immunity tests, e.g. BCI, within the development process. EMC simulations can help to calculate the effect of electromagnetic disturbances coupled to the bus system cable network. To protect the transceiver on PCB level against ESD, additional overvoltage protection elements are often used. However, the non linear ESD protection circuits and high disturbance levels can change the shape of the bus signal and the transceivers may not be able to detect the bus information. For simulation based EMC investigations using large BCI setups exact models of the wires, the ESD protection elements, the behavior of the transceivers, and the BCI injection clamp are necessary. These models were developed and verified with measurements. The simulation results are in good agreement with measurements.