KSZ8081 Physical-Layer Transceivers

The Microchip KSZ8081 is a single-supply 10Base-T/100Base-TX Ethernet physical-layer transceiver for transmission and reception of data over standard CAT-5 unshielded twisted pair (UTP) cable. It is a highly-integrated PHY solution that reduces board cost and simplifies board layout by using on-chip termination resistors for the differential pairs and by integrating a low-noise regulator to supply the 1.2 V core.

It offers the Media Independent Interface (MII) and the KSZ8081RNB offers the Reduced Media Independent Interface (RMII) for direct connection with MII/RMII-compliant Ethernet MAC processors and switches. A 25 MHz crystal is used to generate all required clocks, including the 50 MHz RMII reference clock output for the KSZ8081RNB.

The KSZ8081 provides diagnostic features to facilitate system bring-up and debugging in production testing and product deployment. Parametric NAND tree support enables fault detection between KSZ8081 I/Os and the board. Microchip LinkMD^® TDR-based cable diagnostics identify faulty copper cabling. The KSZ8081MNX and KSZ8081RNB are available in 32-pin, lead-free QFN packages.

Features

• Single-chip 10Base-T/100Base-TX IEEE 802.3-compliant Ethernet transceiver
• MII interface support (KSZ8081MNX)
• RMII v1.2 interface support with a 50 MHz reference clock output to MAC, and an option to input a 50 MHz reference clock (KSZ8081RNB)
• Back-to-back mode support for a 100 Mbps copper repeater
• MDC/MDIO management interface for PHY register configuration
• Programmable interrupt output
• LED outputs for link, activity, and speed status indication
• On-chip termination resistors for the differential pairs
• Baseline wander correction
• HP Auto MDI/MDI-X to reliably detect and correct straight-through and crossover cable connections with disable and enable option
• Auto-negotiation to automatically select the highest linkup speed (10/100 Mbps) and duplex (half/full)
• Power-down and power-saving modes
• LinkMD^® TDR-based cable diagnostics to identify faulty copper cabling
• Parametric NAND Tree support for fault detection between chip I/Os and the board
• Loopback modes for diagnostics
• Single 3.3 V power supply with V_DD I/O options for 1.8 V, 2.5 V, or 3.3 V
• Built-in 1.2 V regulator for core
• Available in 32-pin (5 mm x 5 mm) QFN package