High-Performance Single-Chip 10/100 Ethernet Controller with HP Auto-MDIX
Datasheet
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 through an internal register 27.15, or the external control pins
AMDIX_EN. When disabled the TX and RX pins can be configured with the Channel Select
(CH_SELECT) pin as desired.
The figure below shows the signal names at the RJ-45 connector, The mapping of these signals to the pins on
the LAN9218 is as follows:
TXP = TPO+
TXN = TPO-
RXP = TPI+
RXN = TPI-
Figure 4.3 Direct cable connection vs. Cross-over cable connection.
Revision 1.5 (07-18-06)
SMSC LAN9218
DATA6S4HEET
SMSC [ SMSC CORPORATION ]
