lxt9781 Intel Corporation, lxt9781 Datasheet - Page 22

• Manufacturer Part Number: lxt9781
• Description: Fast Ethernet 10/100 Multi-port Transceiver With Rmii
• Manufacturer: Intel Corporation

LXT9761/9781 — Fast Ethernet 10/100 Multi-Port Transceiver with RMII
2.2
2.2.1
2.2.1.1
22
Figure 5. LXT97x1 Interfaces
Interface Descriptions
10/100 Network Interface
The LXT97x1 supports both 10BASE-T and 100BASE-TX Ethernet over twisted-pair, or 100
Mbps Ethernet over fiber media (100BASE-FX). Each network interface port consists of four
external pins (two differential signal pairs). The pins are shared between twisted-pair (TP) and
fiber. The LXT97x1 pinout is designed to interface seamlessly with dual-high stacked RJ45
connectors. Refer to
The LXT97x1 output drivers generate either 100BASE-TX, 10BASE-T, or 100BASE-FX output.
When not transmitting data, the LXT97x1 generates 802.3-compliant link pulses or idle code.
Input signals are decoded either as a 100BASE-TX, 100-BASE-FX, or 10BASE-T input,
depending on the mode selected. Auto-negotiation/parallel detection or manual control is used to
determine the speed of this interface.
Twisted-Pair Interface
When operating at 100 Mbps, MLT3 symbols are continuously transmitted and received. When not
transmitting data, the LXT97x1 generates “IDLE” symbols.
During 10 Mbps operation, Manchester-encoded data is exchanged. When no data is being
exchanged, the line is left in an idle state.
The LXT97x1 supports either 100BASE-TX or 10BASE-T connections over 100
Unshielded Twisted Pair (UTP). Only a transformer, series capacitors, load resistors, RJ45 and
bypass capacitors are required to complete this interface. On the receive side, the internal
Control I/F
Port LEDs/
Hardware
DATA
MDIO
Mgmt
RMII
Status
Quick
I/F
I/F
I/F
VCC
Table 3
TXDn_0
TXDn_1
TXENn
RXDn_0
RXDn_1
CRS_DVn
RXERn
MDIO
MDC
MDINT
MDDIS
LED/CFGn_n
LEDS_n
LEDLAT
LEDCLK
ADD<4:0>
QSTAT
QCLK
for specific pin assignments.
TPFIPn
TPFINn
TPFOPn
TPFONn
RBIAS
GNDD
VCCD
VCCIO
22.1k
.01uF
+3.3V
+3.3V
Network
I/F
Category
Datasheet