Design of automotive Single Pair Ethernet switch with Power over Data Line

Nowadays, in the automotive sector, there is a need to transfer a large amount of data in the shortest possible time to ensure the functioning of systems such as ADAS or Infotainment and there’s also the necessity to reduce the weight and complexity of wiring especially when considering a zonal architecture. To satisfy these requests, it’s developed a single-pair Ethernet switch with Power over Data Line that exploits the 100Base-T1 protocol described by the IEEE 803.2 standard. This implies that data and power share the same twisted pair, not necessarily shielded, with the possibility of exploiting all the upper layers, already widely developed as regards the transmission of packets, which are based on Ethernet. The project is developed in collaboration with Bylogix, a company that provides OEM’s and Tier 1’s electrical and electronic engineering services and solutions for the automotive industry. Clearly being an automotive system, each component selected has the automotive grade certification, and the design is thought to satisfy the test provided by the ISO 16750 standard. The development starts by first studying the potential solutions, then moving on to a simulation phase, which focuses on crucial aspects of this system, including the coupling network and all the control circuits required for the PoDL. As regards the PCB design, a floor planning phase is carried out first, and then the layout and routing ones are completed using software such as Altium. There are many side benefits in adopting this device as a partial replacement of the Power Distribution Unit and an increase in transmission security, as it is possible, in future developments, to implement encrypted communication, for example via TLS thanks to the use of the ISO-OSI stack, thus reducing the possibility of data theft and sniffing.