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ICS1892, Rev. D, 2/26/01
February 26, 2001
22
Chapter 5
Operating Modes Overview
ICS1892 Data Sheet
2000-2001, Integrated Circuit Systems, Inc.
All rights reserved.
5.5
100Base-TX Operations
The ICS1892 100Base-TX mode is a primary operating mode that provides 100Base-TX physical layer
(PHY) services as defined in the ISO/IEC 8802-3 standard. In the 100Base-TX mode, the ICS1892 is a
100M translator between a MAC/repeater and the physical transmission medium. As such, the ICS1892
has two interfaces, both of which are fully configurable: one to the MAC/repeater and one to the Link
Segment. In 100Base-TX mode, the ICS1892 provides the following functions:
Data conversion from both parallel-to-serial and serial-to-parallel formats
Data encoding/decoding (4B/5B, NRZ/NRZI, and MLT-3)
Data scrambling/descrambling
Data transmission/reception over a twisted-pair medium
To accurately transmit and receive data, the ICS1892 employs DSP-based wave shaping, adaptive
equalization, and baseline wander correction. In addition, in 100Base-TX mode, the ICS1892 provides a
variety of control and status means to assist with Link Segment management. For more information on
100Base-TX, see
Section 7.4, “Functional Block: 100Base-TX TP-PMD Operations”
.
5.6
10Base-T Operations
The ICS1892 10Base-T mode is another primary operating mode that provides 10Base-T physical layer
(PHY) services as defined in the ISO/IEC 8802-3 standard. In the 10Base-T mode, the ICS1892 is a 10M
translator between a MAC/repeater and the physical transmission medium. As such, the ICS1892 has two
interfaces, both of which are fully configurable: one to the MAC/repeater and one to the Link Segment. In
10Base-T mode, the ICS1892 provides the following functions:
Data conversion from both parallel-to-serial and serial-to-parallel formats
Manchester data encoding/decoding
Data transmission/reception over a twisted-pair medium
In addition, in 10Base-T mode, the ICS1892 provides a variety of control and status means to assist with
Link Segment management. For more information on 10Base-T, see
Section 7.5, “Functional Block:
10Base-T Operations”
.
5.7
Half-Duplex and Full-Duplex Operations
The ICS1892 supports half-duplex and full-duplex operations for both 10Base-T and 100Base-TX
applications. Full-duplex operation allows simultaneous transmission and reception of data, which
effectively doubles the Link Segment throughput to either 20 Mbps (for 10Base-T operations) or 200 Mbps
(for 100Base-TX operations).
As per the ISO/IEC standard, full-duplex operations differ slightly from half-duplex operations. These
differences are necessary, as during full-duplex operations a PHY actively uses both its transmit and
receive data paths simultaneously.
In 10Base-T full-duplex operations, the ICS1892 disables its loopback function (that is, it does not
automatically loop back data from its transmitter to its receiver and disable its SQE Test function).
In both 10Base-T and 100Base-TX full-duplex operations, the ICS1892 asserts its CRS signal only in
response to receive activity while its COL signal always remains inactive.
For more information on half-duplex and full-duplex operations, see the following sections:
Section 8.2, “Register 0: Control Register”
Section 8.2.8, “Duplex Mode (bit 0.8)”
Section 8.3, “Register 1: Status Register”
Section 8.6, “Register 4: Auto-Negotiation Register”