Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Far-end system
TXD
TX
RX
10/100
Ethernet
MAC
X
Link
Partner
CAT-5
XFMR
RXDX
Digital
Analog
SMSC
Ethernet Transceiver
Figure 3.13 Far Loopback Block Diagram
Connector Loopback
3.8.8.3
The device maintains reliable transmission over very short cables, and can be tested in a connector
loopback as shown in Figure 3.14. An RJ45 loopback cable can be used to route the transmit signals
an the output of the transformer back to the receiver inputs, and this loopback will work at both 10 and
100.
1
2
TXD
RXD
TX
RX
10/100
Ethernet
MAC
3
4
5
6
7
8
XFMR
Digital
Analog
RJ45 Loopback Cable.
Created by connecting pin 1 to pin 3
and connecting pin 2 to pin 6.
SMSC
Ethernet Transceiver
Figure 3.14 Connector Loopback Block Diagram
3.9
Application Diagrams
This section provides typical application diagrams for the following:
Simplified System Level Application Diagram
Power Supply Diagram (1.2V Supplied by Internal Regulator)
Power Supply Diagram (1.2V Supplied by External Source)
Twisted-Pair Interface Diagram (Single Power Supply)
Twisted-Pair Interface Diagram (Dual Power Supplies)
SMSC LAN8720A/LAN8720Ai
41
Revision 1.4 (08-23-12)
DATASHEET
SMSC [ SMSC CORPORATION ]
