Lowering the cost of single pair Ethernet implementation through insulation displacement (IDC) and press- fit technologies.
By Kevin McGonigle, Senior Sales Strategy Manager at Rutronik, Daniel West, Lead Technical Applications Engineer at KYOCERA AVX, and Julian T. Wilson, Market Research Engineer II at KYOCERA AVX.
In the early 90’s Geoffrey A. Moore, a Silicon Valley-based consultant, promoted the marketing concept of “Crossing the Chasm” in a best- selling book by the same title. The “chasm” describes the gap that exists between the initial smaller-size market, comprised of innovators and early adopters of technology products, and the larger-sized early majority/mainstream market where the new product technology takes hold and companies offering products based on the new innovation tend to flourish. Successfully crossing the chasm creates a new environment known as the tornado, and is characterized by rapid growth, intense competition, additional market disruptions, and significant growth opportunities for market leaders.
In a very real sense, it’s only recently that Single Pair Ethernet (SPE) technology and products have successfully crossed the chasm and are now entering the market tornado. While Ethernet technology turned 50 years old last year, the single-pair variants are relative newcomers. SPE describes the transmission of Ethernet over only one pair of twisted copper wires. In addition to data transmission via Ethernet, SPE also enables a simultaneous power supply of terminal devices via PoDL (Power over Data Line). Previously, this required two pairs for Fast Ethernet (100MB) and four pairs for Gigabit Ethernet. In addition to space and weight savings with less wire, SPE transmits 1GBit/s up to a distance of 40 meters.
Change comes quickly in the technological world. With SPE, standards are settling in, use cases are showing success, and the applications space is growing rapidly. Vendors are releasing compliant products ranging from physical layer components such as specific SPE PHY chips, magnetics, circuit protection components, cables, and interconnection systems, all the way up to Layer 3 switches with SPE ports.
As SPE begins to roll out, there will be a need for easy-to-implement, yet reliable wire-to-board interconnects. Purchasing finished cable and connector assemblies is not always economical or viable. However, it is also undesirable to work with time-consuming and difficult-to-process connectors. Insulation Displacement Connectors (IDC) and Press-Fit technology require no crimping or soldering processes and are easily converted to a streamlined process while maintaining the versatility of cable lengths and positioning. In addition to reliable retention forces and gas-tight seals afforded by the cold weld mechanism of IDC, signal integrity is preserved and performs beyond transmission standards set for SPE connectors.

Selecting passive components for circuit protection on Ethernet networks will also be challenging, but recent MLV (multilayer varistor) advancements like OPEN (One Pair Ether- Net) qualified devices will make this process easier. OPEN qualified devices meet strict size, weight, overvoltage suppression, and signal integrity standards for Ethernet networks set by the automotive industry.
It is important to consider OPEN qualified devices because the OPEN Alliance and the SPE group are organizations comprised of leading manufacturers and adopters of single pair Ethernet communications; OPEN is concerned with exclusively automotive applications and the SPE group focused primarily on industrial applications. Some of the overlap of transient suppression requirements and bit rates of automotive and industrial applications will ease circuit protection device selection.
MLVs are significant because silicon-based TVS (transient voltage suppression) diodes are commonly used to protect circuits, but shortages are expected to impact these devices along with IC (integrated circuit) shortages.

In summary, IDCs excel at wire-to-board assembly speed and simplicity due to their design requiring no wire preparation like clamping or soldering terminations on wires. Press-Fit connectors have excellent board placement versatility due to their short pin lengths that have high retention forces and no soldering requirements making it convenient for boards going through multiple reflows and prevents connectors from undergoing multiple temperature cycles.
MLVs provide a strong alternative to TVS diodes for circuit protection due to the ongoing silicon shortage, which is projected to impact the TVS diode industry. In addition to availability, MLVs can survive highly repetitive strikes, require no temperature derating, can be designed for low capacitance loading for high-frequency signal lines, and are extremely volumetrically efficient when compared to TVS diodes.
As SPE picks up steam, solderless process connectors and Ethernet- qualified MLVs will be able to support unique design constraints. As with any new technology, the main drivers behind market success are economic questions. Will adopting the new technology make us money, save us money, create new customers or new demand from existing customers, allow us to serve our customers better, etc.? Enter the tornado for SPE. Buckle up Toto, we’re not in Kansas anymore.