General Description

The Realtek RTL8221B(I)-VM-CG (hereafter referred to as the RTL8221B(I)-VM, except where differences exist) is a highly integrated Ethernet PHY transceiver that is compatible with 10BASE-Te, 100BASE-TX, 1000BASE-T, and 2.5GBASE-T, and is fully compatible with both the IEEE 802.3 standard and the NBASE-T™ Alliance PHY. It provides all the necessary physical layer functions to transmit and receive Ethernet packets over CAT.5e UTP cable.

The RTL8221B(I)-VM provides a MACsec feature of IEEE MAC Security Standard protocol. The integrated functionality with MACsec security engines separate egress and ingress traffic and provides data integrity check, confidentiality and replay protect.

The RTL8221B(I)-VM uses state-of-the-art DSP technology and Analog Front End (AFE) to enable high-speed data transmission and reception over UTP cable. Functions such as Crossover Detection & Auto-Correction, polarity correction, MDI swap, adaptive equalization, cross-talk cancellation, echo cancellation, timing recovery, RFI protection, thermal management, loopback diagnostic capability, and error correction are implemented in the RTL8221B(I)-VM to provide robust transmission and reception capabilities.

Data transfer between MAC and PHY is via the SERDES (Serializer-Deserializer) interface, which supports SGMII, HiSGMII, and 2500Base-X. The RTL8221B(I)-VM operates at various digital I/O voltages, including 3.3V and 1.8V.


  • Compatible with IEEE 802.3, IEEE 802.3u, IEEE 802.3ab
  • Supports IEEE 802.3az (Energy Efficient Ethernet)
  • Supports IEEE 802.3bz (2.5GBASE-T)
  • Support MACsec compatible with IEEE 802.1AE, IEEE 802.1AEbn, IEEE 802.1AEbw
  • Supports Full Duplex flow control (IEEE 802.3x)
  • Supports IEEE 802.3 optional ability (Energy Efficient Ethernet and Fast Retrain)
  • Integrated 10M BASE-Te and 100M/1000M/2.5GBASE-T IEEE 802.3 compatible transceiver
  • Supports 2.5G Lite (1G data rate) mode
  • Auto-Negotiation with Extended Next Page capability (XNP)
  • Compatible with NBASE-TTM Alliance PHY Specification
  • Supports pair swap/polarity/skew correction
  • Crossover Detection & Auto-Correction
  • Configurable MDI port ordering (MDI swap) for easy PCB layout
  • Supports hardware CRC (Cyclic Redundancy Check) function
  • Supports power down/link down power saving mode
  • Supports clause 22 and Clause 45 MDC/MDIO management interface
  • Supports rate adaptor for SerDes
  • Selectable SERDES interface to MAC control (SGMII/HiSGMII/2500 BASE-X)
  • Built-in Wake-on-LAN (WOL) over UTP
  • Supports Interrupt function over UTP
  • Supports Parallel Detection
  • Supports PHYRSTB core power Turn-Off
  • Baseline Wander Correction
  • Selectable 3.3/1.8V signaling for MMD access
  • Supports 25MHz crystal or external OSC
  • Provides 25MHz clock source for MAC
  • Provides 3 network customized LEDs with controllable LED Blinking Frequency and Duty Cycle
  • Self-Loopback diagnostic capability
  • Thermal management on PHY
  • 48-pin QFN Green Package
  • 22nm process with ultra-low power consumption
  • Complete hardware support for Synchronous Ethernet and Precision Time Protocol (PTP) including IEEE 1588v1, v2, and 802.1AS
  • Supports SPI Flash (up to 24MB flash size)
  • Industrial grade manufacturing process (RTL8221BI-VB/ RTL8221BI-VM)


  • DTV (Digital TV)
  • MAU (Media Access Unit)
  • CNR (Communication and Network Riser)
  • Game Console
  • Printer and Office Machine
  • DVD Player and Recorder
  • Ethernet Hub
  • Ethernet Switch
  • Base Stations and Controllers
  • Routers, DSLAMs, PON Equipment
  • Test and Measurement Systems
  • Industrial and Factory Automation Equipment
  • Multimedia synchronization and Real Time Networking