This data sheet introduces the features of the 78Q2120C 10/100BASE-TX transceiver
The 78Q2120C transceiver provides full‑duplex 10BASE‑T and 100BASE‑TX operation compliant with IEEE‑802.3. It integrates a Media Independent Interface (MII), ENDEC, scrambler/descrambler, dual‑speed clock recovery, and a complete auto‑negotiation engine. The transmitter includes an on‑chip pulse‑shaper and low‑power line driver, while the receiver features an adaptive equalizer and baseline restoration circuit.
Power management modes include Chip Power‑Down, Receive Power Management, and Transmit High‑Impedance. The device operates from a single 3.3 V supply, offers several LED status indicators, and is packaged in a 64‑pin TQFP. It connects to the network via 1:1 isolation transformers without external filters. This manual is written in Chinese.
| Interface | Integrated MII (Media Independent Interface) |
|---|---|
| Data rates | 10BASE‑T / 100BASE‑TX |
| Supply voltage | 3.3 V ± 0.3 V |
| Package | 64‑Pin TQFP (JEDEC LQFP) |
| Transmit clock frequency (100BASE‑TX) | 125 MHz |
| Transmit clock frequency (10BASE‑T) | 20 MHz |
| Power‑saving modes | Chip Power‑Down, Receive Power Management, Transmit High‑Impedance |
| LED indicators | LINK, TX, RX, COL, 100, 10, FDX |
It supports Chip Power‑Down, Receive Power Management, and Transmit High‑Impedance modes.
An on‑chip frequency synthesizer multiplies the 25 MHz reference clock by 5 to produce a 125 MHz transmit clock.
It is supplied in a 64‑pin TQFP (JEDEC LQFP) package.