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Technical Report: BCM89890 Multigigabit Automotive Ethernet PHY
Future-Proofing: 1000BASE-T1 and Beyond
While the BCM89890 is a 100Mbps device, it is often deployed in mixed-speed networks. Many next-generation designs pair it with a 1000BASE-T1 (1 Gbps) PHY for backbone links while keeping the BCM89890 for leaf nodes (door handles, window lifters, seat controllers). This provides a graceful upgrade path: the central switch can support both speeds, and the BCM89890 remains viable for low-bandwidth, cost-sensitive endpoints well into the 2030s. bcm89890
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, meeting stringent automotive requirements for electromagnetic compatibility (EMC) and extreme temperature operation. Primary Applications The chip is a critical component for Software-Defined Vehicles (SDVs) , where high-speed backbone communication is essential for: Autonomous Driving (ADAS): Grab the reader's attention Provide a brief overview
Verdict: The Broadcom BCM89890 is a highly capable and robust automotive Ethernet PHY transceiver. While it is often overshadowed in marketing materials by its more famous siblings—the BCM89881 and the newer BCM89811 (the world’s first 10G auto Ethernet PHY)—the BCM89890 remains a workhorse for modern vehicle networking, offering excellent EMI performance and reliability for 100Mbps and 1Gbps architectures. which provides detailed specifications
In the high-stakes world of automotive engineering, a new hero was born: the BCM89890. This wasn't just any silicon chip; it was the world’s first IEEE 802.3ch compliant multigigabit Ethernet transceiver, a marvel of modern connectivity designed to be the central nervous system of the next generation of vehicles. The Birth of a Speedster
BCM89890 vs. Other Automotive PHYs
| Feature | BCM89890 (100BASE-T1) | Traditional CAN FD | Traditional 100BASE-TX | | :--- | :--- | :--- | :--- | | Speed | 100 Mbps | 2-5 Mbps | 100 Mbps | | Cable Pairs | 1 (UTP) | 1 (CAN_H/L) | 2 (4 wires) | | Max Length | 15m (auto) / 40m (lab) | 40m | 100m (not used in auto) | | EMI Performance | Very Low (Shaped spectrum) | Moderate | High (Unshaped) | | Wake-up Support | Yes (Sleep/Wake) | Yes | No (Always on) | | Cost per Node | Medium | Low | High (connectors cost) |
- Broadcom Datasheet: The official datasheet for the BCM89890, which provides detailed specifications, features, and functional descriptions.
- Broadcom Website: Broadcom's website offers a wealth of information on their products, including documentation, software, and technical support resources.
- Design Guides: Look for design guides and application notes from Broadcom or other sources, which can provide valuable insights into designing with the BCM89890.
1. Magnetics and Common Mode Chokes
Unlike traditional Ethernet, 100BASE-T1 does not require isolation magnetics in the same way. However, the BCM89890 still requires a Common Mode Choke (CMC) on the MDI (Media Dependent Interface) lines to suppress EMI. Broadcom’s reference designs typically specify a specific CMC part number from TDK or Murata.
