[Realtek]

General Description
The RTL8305S is a highly integrated layer 2 single chip switch controller which incorporates 5 MACs (Media Access Controller), 5 physical layer transceivers, 1-Mbit SRAM and 1K-entry look-up table into one single chip.
The RTL8305S contains 5 ports, and each one provides support for a 10Base-T (10Mbps) or 100Base-TX (100Mbps) network connection. The fifth port (port 4) can be configured as a MII/SNI to work with a routing engine, HomePHY or a fiber transceiver for a 100Base-FX application. And each operation mode can be easily set up by hardware strapping upon restart or power-on.
The RTL8305S is designed for a stand-alone switch system through hardware strapping upon reset to achieve unmanaged operation and can be easily integrated with xDSL/Cable modem router. With the least peripheral components and using a 25MHz crystal, the RTL8305S has the best system cost structure. The integrated RTL8305S chip benefits from low power consumption and ease of use for SOHO 5-port switch or xDSL/Cable router applications.

FEATUREs
■ 5-port integrated switch with physical layer and transceiver for 10Base-T and 100Base-TX with 5-port 10/100M UTP or 4-port 10/100M UTP + 1-port MII/SNI
■ PHY mode MII/SNI interface for router application
■ MAC mode MII interface for HomeLAN/100Base-FX application
■ 1Mbit internal RAM for packet buffer
■ Internal 1K look-up table entries
■ 25MHz crystal or OSC input
■ Non-blocking wire-speed reception and transmission
■ Fully compliant with IEEE 802.3/802.3u
■ Supports broadcast storm filtering function
■ Support full duplex 802.3x flow control and half duplex back-pressure flow control
■ LED indicators for link/activity, speed, full/half duplex and collision
■ LEDs blinking upon reset for LED diagnostics
■ Unmanaged operation by strapping upon reset
■ Power saving with cable detection
■ Low power consumption at 3.3V operating voltage
■ 128-pin PQFP package