Cables and Connectors Drive Innovations in Tomorrow’s Connected Cars

There is a tremendous transformation underway in the automotive industry as consumers demand greater functionality from their vehicles. According to a November 2020 survey commissioned by Molex on “The Future of Automotive,” standard car features in 2030 will be driven primarily by technology innovation and customer demand.

For example, growing interest in advanced driver assistance system (ADAS) or autonomous driving (AD) applications places greater emphasis on intelligent in-vehicle networking (IVN) and wiring systems. While often overlooked in importance, cables and connectors form a car’s critical nervous system and must deliver fast, uninterrupted signal transmissions within the vehicle.

Each new functional signal delivered by an ADAS/AD application demands cabling and connectors that can support the associated latency, frequency and bandwidth requirements. These essential components also must seamlessly address the rising number of devices and electronic control units (ECUs) across the IVN to ensure the highest levels of performance and functionality.

Single-Ended or Differential?

There’s much debate and discussion about whether single-ended or differential cabling/connector solutions are best positioned to address system architecture and performance needs. I led a deep-dive discussion on this topic at the Automotive SerDes conference in October, offering insights and perspectives.

Making the choice between single-ended (i.e., coax cables are terminated with coax connectors on both ends of the cable) or differential (i.e., shielded twisted pair or shielded parallel pair with fully shielded differential connectors on both ends of the cable) strictly depends on the application. The challenge in picking the best approach is complicated by the growing number of applications with different protocols, which increases wiring, complexity and weight.

A general distinction between single-ended and differential cables is that the latter sends a signal over two cable conductors while the single-ended uses one. The pair of conductors enables opposite polarity to cancel interfering signals from the environment. There also are several types of differential cables. Shielded twisted pair (STP) helps suppress noise with the twisted conductors’ construction while shielded parallel pair (SPP) refers to two conductors that are parallel to each other for the most part, which enables better IL performance due to physical length benefits resulting from the reduction in twisting.

Shielded twisted pair (STP) helps equalize and suppress noise while shielded parallel pair (SPP) means the two cable strands are straight.

There are variants for the cable shielding too, and the material from which the cables are made is also relevant. The subsequent placement within the vehicle also should help determine the material. For example, if a cable is installed in a door that frequently is opened and closed, it must be flexible. For example, if a cable is located in the engine compartment, the temperature rating of the cable assembly must be updated to 125 degrees Celsius. In general, while differential cables are better at suppressing background noises, they are more expensive and heavier than single-ended alternatives.

To better understand where people stand on this topic, I posed a question to the SerDes conference attendees about which approach was poised to win in the long run. Interestingly, the majority chose differential cabling for the biggest growth potential in the future.

Standardization and Collaboration are Key

As long-time members of the Automotive SerDes Alliance (ASA), Molex is committed to supporting the standardization of asymmetric SerDes technology. Clearly, we need collaboration among cable/connector solutions providers, IVN suppliers and automotive OEMs to address potential strengths and limitations of different approaches while ensuring designs are aligned with OEM strategies.

Another important alignment is with chipset manufacturers. Strategic cooperation with chip developers will ensure that cable/connector solutions deliver the highest quality solutions at the best cost structure to the OEM. Increased regulation also will continue to drive the need for high-speed connectors indirectly, mostly as a result of broader safety initiatives.

Requirements are Changing

IVN and ADAD/AD are drastically changing cabling requirements, as more and more vehicles require higher connectivity and increased signal transmissions. Next-generation capabilities necessitate an increasing need for uninterruptible backup, so the entire system must accommodate reliable failover.

Meanwhile, higher data rates represent another important wiring challenge, as they demand higher quality cables. Constant quality adjustments and improvements regarding signal transmission are one of the main challenges for wiring of connected vehicles. Additionally, cables must protect against ambient noise, electromagnetic interference (EM) and other interfering signals. This requires regular, early testing of cable connections along with rapid troubleshooting of fault occurrences.

Cables and connectors will continue to have an increased profile as the presence of connected cars becomes more and more of a reality every year. In 2021, watch for the increasing roster of applications and protocols to bring standardization to the forefront, so everyone involved can reach their desired destinations.

Signal Integrity Engineering Supervisor at Molex