10/100BASE-TX Transceiver
Description
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78Q2120C 10/100BASE-TX Transceiver
August 2003
DESCRIPTION
The 78Q2120C 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 function.
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 (Cat5 UTP) cabling for 100BASE-TX/10BASE-T and Category-3 unshielded twisted pair for 10BASE-T, 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 an advanced CMOS process for high performance and low power operation.
FEATURES
• 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 fullfeatured auto-negotiation function Full duplex operation capable PCS Bypass supports 5-bit symbol interface Register-programmable transmit amplitude Dual speed digital clock recovery Automatic polarity correction during autonegotiation and 10BASE-T signal reception Power-saving and power-down including transmitter disable modes
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• • • • • • • • • •
LED indicators: LINK, TX, RX, COL, 100, 10, FDX User programmable Interrupt pin 64-Pin TQFP (JEDEC LQFP) package Single 3.
3 V ± 0.
3V Supply
BLOCK DIAGRAM
4B/5B Encoder, Scrambler, Parallel/Serial
100M
NRZ/NRZI MLT3 Encoder TX CLK GEN
Pulse Pulse Shaper Shaper and Filter TXOP/N MDI RXIP/N Auto Negotiation 10M 100M
RX_CLK TX_CLK RXD[3:0] TXD[3:0] Manchester Decoder, Parallel/Serial Serial/Parallel Descrambler, 5B/4B Decoder PS VCC GND MII Registers & Interface Logic 10M Para...
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