Single Pair Ethernet for Industrial Applications


Starting in the early 1980s as a communication protocol for computer networks, Ethernet and its associated standards has become the most used protocol in industry communication. Copper cables with 2-pairs for Fast Ethernet and 4-pairs cables for Gigabit Ethernet are the core elements in enterprise and industrial networks. With the new Single Pair Ethernet (SPE) technology driven from the car industry, many new use cases are possible to replace analog sensor applications or industrial bus systems.

In 2019 about 59 % of all industrial communication protocols were based on LAN. Still, a high percentage of field bus systems like Profibus or

CC-Link (Control and Communication) are in use as well. Many sensors or actuators inside production facilities don’t have a requirement for a high data rate. But as the distance between these devices and the field switches often is more than 200 m, Ethernet with a maximum cable length of 100 m comes to its limits.

Besides cable length, the (cable)weight, mechanical connector stability and PCB size reduction were the drivers to create a new standard beyond the RJ45 based multi-pair Ethernet. Single Pair Ethernet (SPE) was developed to fulfil these market requirements and enable borderless IP based communication from the cloud to any sensor or actuator.

This Application Note describes the components needed for Single Pair Ethernet from the cable to the PHY chip. The focus will be set for the right EMI filter design for 10BASE-T1L and 100BASE-T1 and to fulfil communication safety requirements according to IEC 62368-1. This will be demonstrated in a PCB to characterize the effectiveness of the component.

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