CS8900A
Crystal LAN™ ISA Ethernet Controller
1.0 INTRODUCTION
1.1 General Description
The CS8900A is a true single-chip, full-duplex,
Ethernet solution, incorporating all of the analog
and digital circuitry needed for a complete Ethernet
circuit. Major functional blocks include: a direct
ISA-bus interface; an 802.3 MAC engine; integrat-
ed buffer memory; a serial EEPROM interface; and
a complete analog front end with both 10BASE-T
and AUI.
1.1.1 Direct ISA-Bus Interface
Included in the CS8900A is a direct ISA-bus inter-
face with full 24 mA drive capability. Its configu-
ration options include a choice of four interrupts
and three DMA channels (one of each selected dur-
ing initialization). In Memory Mode, it supports
Standard or Ready Bus cycles without introducing
additional wait states.
1.1.2 Integrated Memory
The CS8900A incorporates a 4-Kbyte page of on-
chip memory, eliminating the cost and board area
associated with external memory chips. Unlike
most other Ethernet controllers, the CS8900A buff-
ers entire transmit and receive frames on chip,
eliminating the need for complex, inefficient mem-
ory management schemes. In addition, the
CS8900A operates in either Memory space, I/O
space, or with external DMA controllers, providing
maximum design flexibility.
1.1.3 802.3 Ethernet MAC Engine
The CS8900A’s Ethernet Media Access Control
(MAC) engine is fully compliant with the IEEE
802.3 Ethernet standard (ISO/IEC 8802-3, 1993),
and supports full-duplex operation. It handles all
aspects of Ethernet frame transmission and recep-
tion, including: collision detection, preamble gen-
eration and detection, and CRC generation and test.
Programmable MAC features include automatic re-
transmission on collision, and automatic padding
of transmitted frames.
1.1.4 EEPROM Interface
The CS8900A provides a simple and efficient seri-
al EEPROM interface that allows configuration in-
formation to be stored in an optional EEPROM,
and then loaded automatically at power-up. This
eliminates the need for costly and cumbersome
switches and jumpers.
1.1.5 Complete Analog Front End
The CS8900A’s analog front end incorporates a
Manchester encoder/decoder, clock recovery cir-
cuit, 10BASE-T transceiver, and complete Attach-
ment Unit Interface (AUI). It provides manual and
automatic selection of either 10BASE-T or AUI,
and offers three on-chip LED drivers for link sta-
tus, bus status, and Ethernet line activity.
The 10BASE-T transceiver includes drivers, re-
ceivers, and analog filters, allowing direct connec-
tion to low-cost isolation transformers. It supports
100, 120, and
150 Ω
shielded and unshielded ca-
bles, extended cable lengths, and automatic receive
polarity reversal detection and correction.
The AUI port provides a direct interface to
10BASE-2, 10BASE-5 and 10BASE-FL networks,
and is capable of driving a full 50-meter AUI cable.
1.2 System Applications
The CS8900A is designed to work well in either
motherboard or adapter applications.
1.2.1 Motherboard LANs
The CS8900A requires the minimum number of
external components needed for a full Ethernet
node. Its small-footprint package and high level of
integration allow System Engineers to design a
complete Ethernet circuit that occupies as little as
1.5 square inches of PCB area (Figure 1). In addi-
tion, the CS8900A’s power-saving features and
CMOS design make it a perfect fit for power-sensi-
CIRRUS LOGIC PRODUCT DATA SHEET
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DS271PP3
CIRRUS [ CIRRUS LOGIC ]
