High speed real-time Ethernet communication is becoming increasingly important for time sensitive applications in industrial automation and automotive systems. Traditional multi pair Ethernet often falls short in meeting the requirements of such applications due to its uncertain performance, bulky cable harnesses, and high power consumption.
A more effective solution relies on the Single Pair Ethernet (SPE) standard, which can provide a simplified physical layer (PHY), but may pose performance challenges in terms of long cable transmission distance and functional safety readiness, as well as implementation challenges related to obtaining effective design resources. Engineers need a comprehensive solution that can meet the strict performance requirements of real-time SPE networks while accelerating implementation speed.
This article outlines the networking requirements and related issues faced by designers of critical, time sensitive applications, particularly in the industrial and automotive fields. Then, Microchip Technology's SPE solution was introduced, including Ethernet PHY transceivers, evaluation boards, and related design resources, which can help designers address new challenges encountered in implementing standard compliant SPE network systems.
How key application requirements drive the need for real-time Ethernet
Real time Ethernet is playing an increasingly important role in many critical industrial and automotive applications. In the Industrial Internet of Things (IIoT) and industrial control systems, high-precision coordination between sensors, controllers, and actuators requires protocols such as IEEE 1588 Precision Time Protocol (PTP) to support deterministic communication networks. In automotive applications, including advanced driver assistance systems (ADAS), infotainment, and remote information processing subsystems, reliable real-time data exchange requires the ability to withstand extreme conditions in the vehicle environment.
Whether in the factory workshop or in the car, time sensitive networks must ensure low and bounded latency, high fault tolerance, and minimal jitter. The ability to maintain cross device synchronization is crucial, especially in environments where millisecond response time is critical for system operation and security. At the same time, network solutions must adapt to the limited space of network subsystems in manufacturing units or vehicle chassis.
How to meet the requirements of time sensitive and space limited applications for networks
According to the IEEE 802.3bw (100BASE-T1) and IEEE 802.3bp (1000BASE-T1) standards, SPE is suitable for Gigabit Ethernet (GbE) in industrial and automotive applications and has become a simplified physical layer alternative to traditional Ethernet. SPE supports strict requirements for time sensitive applications while reducing cable complexity and system costs. However, despite these advantages, SPE based network designers still face challenges in integrating appropriate devices and ensuring their functional security readiness.
Microchip Technology's LAN8872 1000BASE-T1 SPE PHY transceiver (Figure 1) and related design resources can help developers address these emerging challenges when implementing standard compliant SPE networks. LAN8872 integrates a complete PHY subsystem, including physical coding sublayer (PCS), finite state machine (FSM), analog front-end (AFE), low dropout (LDO) regulator, voltage monitoring, on-chip termination, and integrated filtering.
Schematic diagram of Microchip LAN8872 integrated 1000BASE-T1 PHY transceiver (click to enlarge)
Figure 1: LAN8872 provides an integrated 1000BASE-T1 PHY transceiver, including PCS, LDO regulator, voltage monitoring AFE、FSM、 Complete functions such as on-chip terminals and integrated filtering. (Image source: Microchip Technology)
LAN8872 has built-in support for IEEE 1588-2019 and IEEE 802.1AS-2020 precision clock synchronization protocol standards, and is fully compatible with real-time Ethernet audio and video bridging (AVB) and IEEE 802.1 time sensitive network (TSN) standards. The deterministic timing function of LAN8872 can help developers maintain tight synchronization between multiple systems, and its energy management function can meet people's demand for robust low-power connections even in harsh environments.
Simplify low-power SPE network design
LAN8872 adopts Microchip's EtherGREEN energy-saving technology, which enables the device to achieve a typical consumption of only 15 microamperes (μ A) in ultra-low power sleep mode. This device supports the remote sleep and wake-up mechanism of OPEN Alliance Technical Committee 10 (TC10) standard, and can recognize sleep requests and respond to WAKE-IN pulse wake-up. Its INH output allows the device to enable or disable the electronic control unit (ECU) power supply. LAN8872 is equipped with Microchip's FlexPWR power management technology, which further saves energy through variable I/O and core power supply voltage.
The high integration of LAN8872 further simplifies the design. In addition to its extensive integration functions, the combination of on-chip terminal resistors and integrated transmission filtering capabilities makes the solution compact in size and low in electromagnetic interference (EMI). For system level integration, LAN8872 has a reference clock output and a standard serial gigabit media independent interface (SGMII), simplifying the interface with Ethernet media access controllers (MAC) or devices with MAC functionality, including system on chip (SoC), microcontroller (MCU), and field programmable gate array (FPGA) (Figure 2).
Microchip ATA8520D Sigfox transceiver schematic diagram
Figure 2: Developers only need a few additional components to integrate the LAN8872 PHY transceiver into their SPE network solution. (Image source: Microchip Technology)
LAN8872 complies with the IEEE 802.3bp-2016 standard and is designed to provide gigabit performance through a single pair of wires while supporting troubleshooting in critical industrial and automotive networks. This device is helpful for network diagnosis, and its features include short circuit or open circuit cable defect detection, receiver signal quality indicator (SQI), overheat protection, undervoltage protection, full state interrupt support, and various loopback and test modes.