LAN91C100FD REV. B
FEAST Fast Ethernet Controller
with Full Duplex Capability
FEATURES
Dual Speed CSMA/CD Engine (10 Mbps and 100
Mbps)
Compliant with IEEE 802.3 100BASE-T
Specification
Supports 100BASE-TX, 100BASE-T4, and
10BASE-T Physical Interfaces
32 Bit Wide Data Path (into Packet Buffer Memory)
Support for 32 and 16 Bit Buses
Support for 32, 16 and 8 Bit CPU Accesses
Synchronous, Asynchronous and Burst DMA
Interface Mode Options
128 Kbyte External Memory
Built-in Transparent Arbitration for Slave Sequential
Access Architecture
Early TX, Early RX Functions
Flat MMU Architecture with Symmetric Transmit
and Receive Structures and Queues
MII (Media Independent Interface) Compliant MAC-
PHY Interface Running at Nibble Rate
MII Management Serial Interface
Seven Wire Interface to 10 Mbps ENDEC
EEPROM-Based Setup
Full Duplex Capability
GENERAL DESCRIPTION
The LAN91C100FD is designed to facilitate the implementation of first generation Fast Ethernet adapters and connectivity
products. For this first generation of products, flexibility dominates over integration. The LAN91C100FD is a digital device
that implements the MAC portion of the CSMA/CD protocol at 10 and 100 Mbps, and couples it with a lean and fast data
and control path system architecture to ensure the CPU to packet RAM data movement does not cause a bottleneck at 100
Mbps.
Total memory size is 128 Kbytes, equivalent to a total chip storage (transmit plus receive) of 64 outstanding packets. The
LAN91C100FD is software compatible with the LAN9000 family of products and can use existing LAN9000 drivers (ODI,
IPX, and NDIS) in 16 and 32 bit Intel X86 based environments.
Memory management is handled using a unique MMU (Memory Management Unit) architecture and a 32-bit wide
data path. This I/O mapped architecture can sustain back-to-back frame transmission and reception for superior data
throughput and optimal performance. It also dynamically allocates buffer memory in an efficient buffer utilization
scheme, reducing software tasks and relieving the host CPU from performing these housekeeping functions. The
total memory size is 128 Kbytes (external), equivalent to a total chip storage (transmit and receive) of 64 outstanding
packets.
FEAST provides a flexible slave interface for easy connectivity with industry-standard buses. The Bus Interface Unit
(BIU) can handle synchronous as well as asynchronous buses, with different signals being used for each one.
FEAST's bus interface supports synchronous buses like the VESA local bus, as well as burst mode DMA for EISA
environments. Asynchronous bus support for ISA is supported even though ISA cannot sustain 100 Mbps traffic.
Fast Ethernet could be adopted for ISA-based nodes on the basis of the aggregate traffic benefits.
Two different interfaces are supported on the network side. The first is a conventional seven wire ENDEC interface that
connects to the LAN83C694 for 10BASE-T and coax 10 Mbps Ethernet networks. The second interface follows the MII
(Media Independent Interface) specification draft standard, consisting of 4 bit wide data transfers at the nibble rate. This
interface is applicable to 10 Mbps or 100 Mbps networks. Three of the LAN91C100FD’s pins are used to interface to the
two-line MII serial management protocol. Four I/O ports (one input and three output pins) are provided for LAN83C694
configuration.
SMSC DS – LAN91C100FD REV. B
Rev. 01-20-06
SMSC [ SMSC CORPORATION ]
