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 (Cat-5 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 full featured 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 auto negotiation and 10BASE-T signal reception
• Power-saving and power-down modes including transmitter disable
• 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