KSZ9131RNXI for Triple-Speed Ethernet Connectivity

ElecSuppliers Part Number GuideSep 06, 2026

KSZ9131RNXI is a Microchip Gigabit Ethernet PHY designed for embedded systems that require reliable copper Ethernet connectivity across 10Mbps, 100Mbps and 1000Mbps network speeds. As an industrial-temperature version of the KSZ9131 family, it combines multi-speed Ethernet operation with an RGMII host interface and integrated physical-layer functions.

The device is intended for applications where the processor or networking controller needs a dedicated Ethernet PHY capable of connecting to standard twisted-pair infrastructure.

10Mbps to Gigabit Ethernet in One PHY

KSZ9131RNXI supports 10BASE-T, 100BASE-TX and 1000BASE-T operation. This triple-speed capability allows a single hardware design to communicate with legacy Fast Ethernet equipment as well as modern Gigabit Ethernet networks.

Auto-negotiation can determine the appropriate link speed and duplex configuration with the remote Ethernet device. Full-duplex and half-duplex operation are supported according to the selected Ethernet mode.

The PHY is designed for use with standard CAT-5, CAT-5e and CAT-6 twisted-pair cabling, making it suitable for conventional copper Ethernet connections.

RGMII Interface for Embedded Processors

The MAC-side interface uses RGMII, providing a high-speed connection between KSZ9131RNXI and an embedded processor, switch controller or other Ethernet MAC.

RGMII timing can be an important consideration in Gigabit Ethernet PCB design. The KSZ9131 architecture provides programmable timing control that allows designers to adjust the relationship between the data and clock signals and compensate for board-level timing differences.

This can simplify PCB layout and provide additional timing margin when integrating the PHY with different processors.

Integrated Ethernet Functions

KSZ9131RNXI incorporates the major physical-layer functions required for copper Ethernet communication. This reduces the amount of external circuitry needed around the PHY and allows the host system to concentrate on MAC-level networking functions.

The device provides standard management access for configuration and monitoring, while programmable LED functions can indicate link status, activity and operating conditions.

Its integrated architecture is useful in embedded network equipment where PCB area and component count need to be controlled.

Cable Diagnostics for Network Maintenance

Network problems are not always caused by the PHY or processor. Cable faults, connector problems and damaged twisted-pair wiring can also prevent an Ethernet link from operating correctly.

KSZ9131 includes cable diagnostic capabilities that can help analyze the condition of the connected cable. These functions can assist development engineers during board testing and provide useful information when troubleshooting deployed industrial equipment.

The diagnostic features can therefore be valuable in systems where Ethernet connectivity must be maintained over long operating periods.

Industrial Temperature Operation

The KSZ9131RNXI variant is specified for an industrial operating temperature range from -40°C to +85°C. This makes it more appropriate for industrial controllers, automation equipment, communication gateways and embedded networking products than commercial-temperature PHYs.

The device is supplied in a 48-pin VQFN package with an exposed pad, with the package dimensions around 5.05mm × 5.05mm according to the KSZ9131 product identification information.

Its compact footprint allows Gigabit Ethernet functionality to be integrated into relatively space-constrained embedded hardware.

Applications

KSZ9131RNXI can be used in industrial Ethernet controllers, embedded computers, automation gateways, networked measurement equipment and machine communication systems.

It is also suitable for products that need to support multiple generations of Ethernet infrastructure without maintaining separate PHY designs for 10Mbps, 100Mbps and Gigabit connections.

With triple-speed copper Ethernet, RGMII connectivity and industrial-temperature operation, KSZ9131RNXI provides a practical PHY solution for embedded platforms that require flexible and reliable Ethernet networking.