Selecting a Gigabit Ethernet Controller IC

If you’ve used Google or Amazon services, then you’ve taken advantage of one or more data centers. The products we purchase daily rely on connectivity between manufacturing assets, and the computers in your office would not connect to each other without WiFi, fiber, and copper. Ethernet is the backbone of modern LANs and is not going away anytime soon. Designers working on Ethernet-capable products will need to navigate the landscape of component options.

If you’re designing products to operate at gigabit speeds, you’ll need to compare plenty of component options that support networking equipment. Your PHY layer is responsible for interfacing with fiber or copper, but the component that runs the show is a gigabit Ethernet controller IC. This critical component provides the interface between a central processor and your physical layer, and you’ll need to select the right IC for your next application.

Gigabit Ethernet Controller IC Specifications

If you’re working at these intermediate speeds, such as 1 GbE or 10 GbE, you’ll need to select a gigabit Ethernet controller IC that can interface with the PHY and upstream processor. There is a wide range of available processors on the market, and not all of these contain an integrated Ethernet subsystem. Some high-value FPGAs will include an integrated Ethernet subsystem that can run at 100 Gbit/s or faster on a single chip, albeit at a cost of thousands of dollars. These types of controllers are normally used in rack-mount or backplane units for Ethernet over fiber. Fiber optic cables are the critical media for these ultra-high speed applications.

If you’re designing an intermediate range solution, you can still transfer data over twisted-pair copper. Note that copper is still appropriate for 10 GbE over limited distances, although channel pre-compensation and equalization are usually required in longer links (e.g., SerDes channels). The location of a controller IC within an Ethernet-capable product is similar to that shown below:

Ethernet controller and subsystem architecture.

Here, the controller provides the interface between all upstream components, the PHY layer, and any peripherals. Magnetic termination may be included at the controller output when the controller has an integrated PHY layer interface. When you’re weighing your component options, pay attention to the following specifications:

• Available data rates: If you look at data sheets, you’ll see multiple data rates. GbE specs are somewhat backward compatible, i.e., they support lower speeds when necessary.
• Number of interfaces: Your controller can only support so many interfaces. Typical, moderately-priced controllers can support 2-6 PHY layers or SerDes channels.
• Integrated components: Different controller ICs will provide different levels of integration. Some ICs will integrate magnetics, one or more PHY/SerDes interfaces, MAC, or other components/functions.
• Access to peripherals: The controller normally connects to some upstream processor or subsystem via a high-speed interface (e.g., PCIe), but there are other connectivity options. I2C, GPIO, and SPI interfaces are common in gigabit Ethernet controller ICs.

1 GbE and 10 GbE Controller ICs with Integrated PHY

The components shown below are only a portion of the larger ecosystem in an Ethernet-capable device. As costs increase, so will the available features, interfaces, and maximum data rate.

Microchip, KSZ9893RNXI

The KSZ9893RNXI gigabit Ethernet switch IC from Microchip includes two ports with integrated 10/100/1000BASE-T PHYs, and one port with a 10/100/1000 Ethernet MAC. This particular IC is ideal for a range of applications, including standalone Ethernet switches, WiFi access points, industrial control, and broadband modems. Integrated control registers are accessible via I2C, SPI, or MIIM. The on-chip termination resistors and internal biasing for differential pairs reduce component count and power consumption.

For the power-conscious designer, this IC includes power management features, where the clock is switched off and the switch can enter sleep mode. If you’re designing a switch or router for a gigabit Ethernet network, then this component is an excellent choice. The integration of PHY interfaces into this component also saves board space for other features and components.

Block diagram of the KSZ9893RNXI Ethernet switch. From the KSZ9893RNXI datasheet.

Intel, NHI350AM4 S LJ3Z

The NHI350AM4 S LJ3Z gigabit Ethernet controller from Intel provides 1 GbE at a higher price point, but it includes four integrated 1 GbE PHYs and four integrated 1 GbE SerDes channels for long-range links. This component receives data via PCIe 2.0 (5 Gbps) and a 1000BASE-KX interface for blade server backplane connections. This component is specifically designed to provide 1 GbE over copper with lower power consumption in an office, industrial, or data center environment.

NHI350AM4 S LJ3Z gigabit Ethernet controller IC.

Intel, 82599

At the high end of the cost spectrum, the 82599 family of gigabit Ethernet controllers from Intel moves away from the typical router/switch application and into the rack-mount application space. The 82599 family of 10 GbE controllers encompasses three versions:

• 82599EB: Designed for PCIe 2.0, XAUI, KX, KX4, BX, BX4, and CX4 interfaces (dual-port).
• 82599ES: Serial interface for blade implementations (dual-port).
• 82599EN: Serial SFI interface for blade implementations (single-port).

The image below shows the interface diagram for the 82599 family of ICs. As can be seen in the diagram, this component includes several I/Os and supports up to 4 MAUI interfaces. This component would normally connect to a downstream 10 GbE switch through a backplane, or directly to a 10 GbE network through the integrated MAUI PHYs.

Host interface diagram and I/O ports in the 82599 gigabit Ethernet controller IC. From the 82599 datasheet.

Your new networking products will need to include many components beyond a gigabit Ethernet controller IC. You can find the other components for high speed Ethernet you need by searching on Octopart.

Stay up-to-date with our latest articles by signing up for our newsletter.