With New PHY Transceivers, Microchip Progresses Automotive Ethernet

To support new automotive functionality while keeping system complexity low, OEMs are moving away from domain-based solutions and toward zonal architectures. Many of these new architectures rely on the widespread rollout of Ethernet in vehicles, and the recently-released 10BASE-T1S Ethernet standard has been a game changer in expanding and unifying this network. This week, Microchip announced the release of its first automotive-qualified 10BASE-T1S PHY transceivers.

 

Microchip’s new 10BASE-T1S devices aim to simplify automotive zonal architectures. Image used courtesy of Microchip

 

In this piece, we’ll discuss why the 10BASE-T1S standard has long been considered the missing link to automotive communication and how the new PHYs from Microchip are capitalizing on the benefits of this new IEEE Ethernet standard. 

 

Ethernet: An Important Key in the Switch to Zonal Architectures

Unlike domain architectures, where devices are grouped by function, zonal architectures group devices by physical location. The switch to a zonal architecture significantly decreases system complexity. By spatially grouping devices, OEMs can reduce the number of electronic control units (ECUs) in the vehicle and the amount of harness cabling.

 

Automotive zonal architecture. Image used courtesy of Analog Devices

 

Ethernet is key to the success of these new zonal architectures. As a proven transmission media, Ethernet supports scalability, multiple speed grades, and a service-based architecture. It also offers fully-developed safety and security building blocks. Additionally, Ethernet has a clearly-defined and well-understood open system interconnect (OSI) model, making it easier to manage complexity within the automotive network.

 

What Is the 10BASE-T1S Ethernet Standard? 

Within the realm of Ethernet, the 10BASE-T1S Ethernet standard is a significant improvement over previous standards.

The primary aim of this technology is to facilitate collision-free and deterministic transmission on a multi-drop network. To this end, one of the key features of 10BASE-T1S is the implementation of physical layer collision avoidance (PLCA). This means the entire 10 Mbps bandwidth can be used without the risk of data collision, leading to more efficient network operations.

 

10BASE-T1S bus topology. Image used courtesy of Analog Devices

 

The 10BASE-T1S supports an arbitration scheme that ensures each node has deterministic access to the network media within a specific timeframe. This feature guarantees that every node in the network can access the media, thereby ensuring smooth and efficient network communication.

In an automotive context, the 10BASE-T1S Ethernet standard enables the network edges to use Ethernet and internet protocol (IP) to communicate effectively with the rest of the network infrastructure. This integration simplifies the network architecture and makes communication within the network more straightforward and efficient. 

 

Microchip Extends Support for 10BASE-T1S

To support the future of 10BASE-T1S systems, Microchip Technology recently announced the launch of a series of new automotive-qualified 10BASE-T1S devices. The company's new portfolio of 10BASE-T1S devices includes the LAN8670, LAN8671, and LAN8672 PHYs.

With support for 10BASE-T1S, the LAN8670/1/2 devices (datasheet linked) can transmit and receive data at a rate of 10 Mbit/s over a single balanced pair of conductors. This capability enables efficient data transmission, even in environments where space and resources are limited. The devices can also connect multiple PHYs to a common mixing segment. This not only reduces weight and implementation costs by requiring fewer connectors, individual cables, and switch ports but also simplifies the implementation of automotive applications.

 

Internal block diagram of the LAN8670/1/2. Image used courtesy of Microchip

 

These devices are said to feature enhanced EMC/EMI performance to help meet the stringent standards for automotive environments. Other features include support for time-sensitive networking (TSN) and qualification to AEC-Q1000 Grade 1.

Microchip hopes this new series will help simplify the design of far-reaching Ethernet networks that are common to zonal architectures.