78Q2120-64 Datasheet, PDF (1/33 Pages) List of Unclassifed Manufacturers – 10/100BASE-TX Ethernet Transceiver

DESCRIPTION
The 78Q2120 is a 10BASE-T/100BASE-TX Fast
Ethernet transceiver. It includes integrated MII,
ENDECs, scrambler/descrambler, dual-speed clock
recovery, and full-featured auto-negotiation
functions. The transmitter includes an on-chip pulse-
shaper and a low-power line driver. The receiver has
an adaptive equalizer and a baseline restoration
circuit required for accurate clock and data recovery.
The transceiver interfaces to Category-5 unshielded
twisted pair (Cat-5 UTP) cabling, and is connected to
the line media via 1:1 isolation transformers. No
external filter is required. Interface to the MAC is
accomplished through an IEEE-802.3 compliant
media independent interface (MII). The product is
fabricated in a BiCMOS process for high
performance and low power operation, and can
operate from a single 3.3 V or 5 V supply.
78Q2120
10/100BASE-TX
Ethernet Transceiver
FEATURES
April 2000
• 10BASE-T/100BASE-TX IEEE-802.3 compliant TX
and RX functions requiring a dual 1:1 isolation
transformer interface to the line
• Integrated MII, 10BASE-T/100BASE-TX ENDEC,
100BASE-TX scrambler/descrambler, and full-
featured auto-negotiation function
• Full duplex operation capable
• PCS Bypass supports 5-bit symbol interface
• Dual speed clock recovery
• Automatic polarity correction during auto-
negotiation and 10BASE-T signal reception
• Power-saving and power-down modes including
transmitter disable
• BiCMOS technology, operates with a single 3.3V or
5V supply
• LED indicators: LINK,TX,RX,COL,100,10,FDX
• User programmable Interrupt pin
• General Purpose I/O Interface (80-pin package
only)
• 64 and 80-Lead TQFP (JEDEC LQFP),
64-Pin QFP packages
BLOCK DIAGRAM
Transmit
100M
4B/5B Encoder,
Scrambler,
Parallel/Serial
MII Serial
Management
& Control
MII
Registers
&
Interface
Logic
10M
Parallel/Serial,
Manchester Encoder
Manchester Decoder,
Serial/Parallel
Receive
Serial/Parallel,
Descrambler,
5B/4B Decoder
NRZ/NRZI,
MTL3 Encoder
TX Clock
Generator
Pulse Shaper
& Filter
UTP
Drivers
TXOP
TXON
Carrier Sense,
Collision Detect
Auto
Negotiation
Clock
Recovery
Clock
Reference
Adaptive EQ,
Baseline Wander Corrector,
MLT3 Decoder,
NRZI/NRZ
LEDs
10M
UTP
Receiver
100M
LINK
TX
RX
COL
100BT
10BT
FDX
RXIP
RXIN
CKIN
Vcc
Ground