This reference design shows the implementation of an Ethernet interface consisting of a single-pair Ethernet (SPE) PHY with the option for powering the design through Power over Data Lines (PoDL). PoDL is standardized in IEEE802.3bu for 100/1000Base-T1. The standard requires mechanisms like detection and classification of the connected device which does not address the automotive requirements of PoDL. In the automotive sector the car OEM defines which ECUs and sensor modules are used in the system and therefore a detection and classification is not required. This assumption is based on the fact that the network does not change over the lifetime of the vehicle. The boards are designed to fulfill the automotive requirements for a cost- and weight-efficient implementation. This PoDL design is not fully compliant to IEEE802.3bu to address the automotive requirements. In general, PoDL can be used in vehicles in all areas where SPE is already used to connect sensors or actuators. The use of PoDL is particularly recommended for supplying devices with low energy requirements, such as radar modules or remote camera modules which are already connected to a domain- or zone controller.

A PoDL system consists of a (power) source and a (power) sink, which are referred to as Power Sourcing Equipment (PSE) and Powered Device (PD). Regardless of the specific application, the implementation of PoDL requires only minor adjustments to both the source and the sink. The coupling decoupling network (CDN) functions as a frequency filter, with the low-frequency component, particularly the DC voltage, directed to the power tree, while the high-frequency components are treated as data transmitted to the PHY. Additional information on this topic is elaborated in Section 3.3. In this topology, the use of the classic fuse is no longer applicable, which is why the integration of a high-side switch (HSS) is strongly recommended to protect the PD from any damage.