CS8920A Просмотр технического описания (PDF) - Cirrus Logic

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CS8920A

Crystal LAN ISA Plug-and-Play Ethernet Controller

Cirrus Logic 

EEPROM 20 MHz

XTAL

(2.0 sq. in.)

CS8920A

I

S

CS8920A

A

RJ-45 10BASE-T

Figure 1.1. Complete Ethernet Motherboard Solution

The AUI port provides a direct interface to

10BASE-2, 10BASE-5 and 10BASE-FL net-

works, and is capable of driving a full 50-meter

AUI cable.

use of the CS8920A without an attached

EEPROM.

Plug-and-Play Ethernet Adapter Cards

1.2 System Applications

The CS8920A is designed to work well in either

motherboard or adapter applications.

Motherboard LANs

The CS8920A requires the minimum number of

external components needed for an Ethernet

node, allowing a complete Ethernet circuit that

occupies as little as 2.0 square inches of PCB

area (Figure 1.1). In addition, the CS8920A’s

power-saving features make it a perfect fit for

power-sensitive portable and desktop PCs. Moth-

erboard design options include:

The CS8920A’s highly efficient StreamTrans-

ferTM and Auto-Switch DMA options, make it

an excellent choice for high-performance, low-

cost, ISA adapter cards (Fig. 1.2). The

CS8920A’s wide range of configuration options,

listed below, allow engineers to design Ethernet

solutions that meets their particular system re-

quirements.

• A Boot PROM can be added to support disk-

less applications.

• The 10BASE-T transmitter and receiver im-

pedance can be adjusted to support 100, 120,

or 150 Ω twisted pair cables.

• The EEPROM, used to store node-specific

information, such as the Ethernet Individual

Address, can be eliminated by storing infor-

mation in the system CMOS.

• On-chip LED ports can be used for either

optional LEDs, or as programmable outputs.

1.3 Key Features and Benefits

• The 20 MHz crystal oscillator may be re-

placed by a 20 MHz clock signal.

Note: while operation of the CS8920A is possi-

ble without the use of an attached EEPROM,

special design considerations are required. Fur-

thermore, some of the CS8920A functions, such

as Plug and Play capabilities and wakeup frame

recognition are not possible without an attached

EEPROM. Please contact Crystal’s CS8920A

technical support for more information on the

DS238PP1

Very Low Cost

The CS8920A is designed to provide the lowest-

cost Ethernet solutions available for ISA desktop

motherboards, portable motherboards, and

adapter cards. Cost-saving features include:

• Integrated RAM eliminates the need for ex-

pensive external memory chips.

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