What is Automotive Ethernet?

In recent years, the amount of data transmitted in vehicle interiors has been on the rise, and there is a demand for faster communication speeds to accommodate this increase in data volume.
As a result, it has become difficult to cover this with existing data communication standards such as CAN, LIN, and Flexlay.
Automotive Ethernet was introduced to meet the demand for faster in-vehicle communications.

The difference between commonly used Ethernet and in-vehicle Ethernet is shown in the diagram below. *100BASE refers to 100Mbps, and 1000BASE refers to 1000Mbps.
The in-vehicle Ethernet standard is called the "T1 standard" and is based on Broadcom's BroadR-Reach.

• 100BASE-T1: IEEE802.3bw
• 1000BASE-T1: IEEE802.3bp

It is standardized as.
The biggest feature of the T1 standard is that the number of communication pairs is one.

There are two types of CABLES: UTP (Unshielded Twist Cable) and STP (Shielded Twist Cable), and CABLES requirements are defined by TC (Tech Committees) 9 of the OPEN ALLIANCE, which is run for the purpose of standardizing automotive networks.

The main characteristics of CABLES and STP CABLES are as shown in the diagram below.
As the names suggest, UTP CABLES have no shielding, while STP CABLES have a shield that covers the twisted wires.

The typical CABLES requirements (CABLES length and connection configuration) defined in TC9 are shown in the figure below.
For both STP and UTP, the maximum CABLES length is defined as 15m, and the maximum number of relay CONNECTORS is four.