KSZ9031RNXIA RGMII Gigabit Ethernet PHY

ElecSuppliers Part Number GuideSep 06, 2026

KSZ9031RNXIA is a triple-speed Gigabit Ethernet physical layer transceiver from Microchip designed for systems using an RGMII MAC interface. It supports 10BASE-T, 100BASE-TX and 1000BASE-T communication while integrating several functions that help simplify Gigabit Ethernet hardware design.

The device is intended for industrial and embedded networking equipment where flexible RGMII timing, reliable cable communication and compact board implementation are important.

10/100/1000Mbps Ethernet

KSZ9031RNXIA supports three Ethernet speeds through a single PHY: 10Mbps, 100Mbps and 1000Mbps. Auto-negotiation selects the appropriate link speed and duplex mode according to the connected network equipment.

The PHY supports standard CAT-5 twisted-pair Ethernet connections and includes automatic MDI/MDI-X crossover. Pair-swap, pair-skew and pair-polarity detection and correction further simplify physical-layer integration.

Programmable RGMII Timing

The main interface characteristic of KSZ9031RNXIA is its RGMII support. The device follows RGMII Version 2.0 timing requirements and provides programmable delay options for the transmit and receive paths.

This allows designers to adjust TX and RX timing according to the MAC interface and PCB routing. The ability to make timing corrections inside the PHY can reduce the need for additional external delay components.

The PHY can also provide a 125MHz reference clock output, which can be used as a system timing source for compatible RGMII Ethernet designs.

Integrated Termination and Power Design

KSZ9031RNXIA integrates termination resistors for the Ethernet differential pairs, helping reduce the number of external components around the PHY interface.

An integrated LDO controller can support operation from a single 3.3V supply with an external MOSFET used to generate the 1.2V core supply. This approach can simplify the power architecture while maintaining the required internal voltage domains.

The digital I/O supports 1.8V, 2.5V and 3.3V levels, providing compatibility with a wide range of processors and Ethernet MAC devices.

Ethernet Diagnostics

KSZ9031RNXIA includes LinkMD TDR-based cable diagnostics for identifying problems in copper Ethernet cabling. Loopback functions and a programmable LED interface are also available for system testing and network-status indication.

These diagnostic capabilities can be useful during production testing, board bring-up and field troubleshooting.

The device also supports Wake-on-LAN and energy-detect power-down functionality. When an Ethernet cable is not connected, the PHY can enter a lower-power state to reduce unnecessary system consumption.

Industrial Ethernet Package

KSZ9031RNXIA is available in a 48-pin QFN package with a compact 7mm × 7mm footprint. The I temperature grade specifies operation from -40°C to +85°C, making the part suitable for industrial networking environments.

The combination of a compact package, programmable RGMII timing and integrated Ethernet functions makes the device practical for embedded boards where PCB space and interface timing are important design considerations.

Applications

KSZ9031RNXIA can be used in industrial controllers, embedded computers, Ethernet gateways, networked automation equipment, industrial communication modules and Gigabit Ethernet processor boards.

For designs that require a 10/100/1000Mbps PHY with direct RGMII connectivity, programmable TX/RX timing and integrated cable diagnostics, KSZ9031RNXIA provides a well-integrated Ethernet interface solution.