GENERAL DESCRIPTION

The Am79C976 controller is a highly-integrated 32-bit full-duplex, 10/100-Megabit per second (Mbps) Ethernet controller solution, designed to address high performance system application requirements. It is a flexible bus mastering device that can be used in any application, including network-ready PCs and bridge/router designs. The bus master architecture provides high data throughput and low CPU and system bus utilization. The Am79C976 controller is fabricated with advanced low-power 3.3-V CMOS process to provide low operating current for power sensitive applications.

DISTINCTIVE CHARACTERISTICS

■ Integrated Fast Ethernet controller for the

Peripheral Component Interconnect (PCI) bus

— 32-bit glueless PCI host interface

— Supports PCI clock frequency from DC to

33 MHz independent of network clock

— Supports network operation with PCI clock

from 15 MHz to 33 MHz

— High performance bus mastering

architecture with integrated Direct Memory

Access (DMA) Buffer Management Unit for

low CPU and bus utilization

— PCI specification revision 2.2 compliant

— Supports PCI Subsystem/Subvendor

ID/Vendor ID programming through the

EEPROM interface

— Supports both PCI 3.3-V and 5.0-V signaling

environments

— Plug and Play compatible

— Uses advanced PCI commands (MWI, MRL,

MRM)

— Optionally supports PCI bursts aligned to

cache line boundaries

— Supports big endian and little endian byte

alignments

— Implements optional PCI power management

event (PME) pin

— Supports 40-bit addressing (using PCI Dual

Address Cycles)

■ Media Independent Interface (MII) for

connecting external 10/100 megabit per second

(Mbps) transceivers

— IEEE 802.3-compliant MII

— Intelligent Auto-Poll™ external PHY status

monitor and interrupt

— Supports both auto-negotiable and non auto

negotiable external PHYs

— Supports 10BASE-T, 100BASE-TX/FX,

100BASE-T4, and 100BASE-T2 IEEE 802.3-

compliant MII PHYs at full- or half-duplex

■ Full-duplex operation supported with

independent Transmit (TX) and Receive (RX)

channels

■ Includes support for IEEE 802.1Q VLANs

— Automatically inserts, deletes, or modifies

VLAN tag

— Optionally filters untagged frames

■ Provides optional flow control features

— Recognizes and transmits IEEE 802.3x MAC

flow control frames

— Asserts collision-based back pressure in

half-duplex mode

■ Provides internal Management Information

Base (MIB) counters for network statistics

■ Supports PC97, PC98, PC99, and Net PC

requirements

— Implements full OnNow features including

pattern matching and link status wake-up

— Implements Magic Packet™ mode

— Magic Packet mode and the physical address

loaded from EEPROM at power up without

requiring PCI clock

— Supports PCI Bus Power Management

Interface Specification Version 1.1

— Supports Advanced Configuration and

Power Interface (ACPI) Specification Version

1.0

— Supports Network Device Class Power

Management Specification Version 1.0

■ Large independent external TX and RX FIFOs

— Supports up to 4 megabytes (Mbytes)

external SSRAM for RX and TX frame storage

— Programmable FIFO watermarks for both

transmit and receive operations

— Receive frame queuing for high latency PCI

bus host operation

— Programmable allocation of buffer space

between transmit and receive queues (Continue ...)