FINAL
Publication# 16511 Rev: BAmendment/0
Issue Date: May 1994
1

Am79C100

Twisted-Pair Ethernet Transceiver Plus (TPEX Plus)

DISTINCTIVE CHARACTERISTICS

n

CMOS device provides IEEE 802.3-compliant
operation and low operating current from a
single +5 V supply

n

Power Down mode for reduced power
consumption in battery-powered applications

n

Automatic twisted-pair link integrity

n

Pin-selectable twisted-pair receive polarity
detection and automatic inversion of the receive
signal. Polarity indication output pin can
directly drive an LED.

n

Pin-selectable twisted-pair link integrity test
capability conforming to the IEEE 802.3
standard. Link status pin can directly drive
an LED.

n

Transmit, receive, and collision status
indications available on separate, dedicated
pins

n

Outputs can directly drive LEDs with pulses
stretched to ensure LED visibility

n

Internal twisted-pair transmitter digital
predistortion circuit to reduce medium-induced
jitter

n

Pin-selectable SQE Test (heartbeat) enable

n

AUI loopback, Jabber Control, and SQE Test
functions comply with the 10BASE-T standard

n

User-selectable loopback operations

n

Pin-selectable twisted-pair receive threshold
programming for extended distance line lengths

GENERAL DESCRIPTION

The Am79C100 Twisted-Pair Ethernet Transceiver Plus
(TPEX Plus) is an integrated circuit that implements the
medium attachment unit (MAU) functions for the
twisted-pair medium, as specified by the supplement to
the IEEE 802.3 standard (Type 10BASE-T). This de-
vice provides the necessary electrical and functional
interface between the IEEE 802.3 standard attachment
unit interface (AUI) and the twisted-pair cable.
A network based on the 10BASE-T standard can use
unshielded twisted-pair cables, providing an economi-
cal solution to networking by allowing the use of existing
telephone wiring. The Am79C100 provides a minimal
component count and a cost-effective solution to the
design and implementation of 10BASE-T standard
networks.
TPEX Plus provides twisted-pair driver and receiver cir-
cuits, including on-board transmit digital predistortion,
receiver squelch, and an AUI port with pin-selectable
SQE Test enable. The device provides a number of ad-
ditional features, including Link Status indication with
automatic twisted-pair receive polarity detection/
correction and indication; pin-selectable receive
threshold programming for extended distance line
lengths; and Receive Carrier Sense, Transmit Active
and Collision Present indications. The device provides
separate twisted-pair Link Status, Polarity Status,
Receive, Transmit, and Collision outputs to drive LEDs
directly.