LAN8710A Datasheet, PDF (29/82 Pages) SMSC Corporation – Small Footprint MII/RMII 10/100 Ethernet Transceiver with HP Auto-MDIX and flexPWR Technology

3.3
Small Footprint MII/RMII 10/100 Ethernet Transceiver with HP Auto-MDIX and flexPWR^® Technology
Datasheet
HP Auto-MDIX Support
HP Auto-MDIX facilitates the use of CAT-3 (10BASE-T) or CAT-5 (100BASE-T) media UTP
interconnect cable without consideration of interface wiring scheme. If a user plugs in either a direct
connect LAN cable, or a cross-over patch cable, as shown in Figure 3.4, the device’s Auto-MDIX
transceiver is capable of configuring the TXP/TXN and RXP/RXN pins for correct transceiver operation.
The internal logic of the device detects the TX and RX pins of the connecting device. Since the RX
and TX line pairs are interchangeable, special PCB design considerations are needed to accommodate
the symmetrical magnetics and termination of an Auto-MDIX design.
The Auto-MDIX function can be disabled via the AMDIXCTRL bit in the Special Control/Status
Indications Register.
RJ-45 8-pin straight-through
for 10BASE-T/100BASE-TX
signaling
TXP 1
TXN 2
RXP 3
Not Used 4
Not Used 5
RXN 6
Not Used 7
Not Used 8
1 TXP
2 TXN
3 RXP
4 Not Used
5 Not Used
6 RXN
7 Not Used
8 Not Used
Direct Connect Cable
RJ-45 8-pin cross-over for
10BASE-T/100BASE-TX
signaling
TXP 1
TXN 2
RXP 3
Not Used 4
Not Used 5
RXN 6
Not Used 7
Not Used 8
1 TXP
2 TXN
3 RXP
4 Not Used
5 Not Used
6 RXN
7 Not Used
8 Not Used
Cross-Over Cable
Figure 3.4 Direct Cable Connection vs. Cross-over Cable Connection
SMSC LAN8710A/LAN8710Ai
29
DATASHEET
Revision 1.4 (08-23-12)