Micrel, Inc.
KSZ8041NL/RNL
The KSZ8041RNL RMII pin connections to the MAC are shown in Figure 3.
Figure 3. KSZ8041RNL RMII Interface
HP Auto MDI/MDI-X
HP Auto MDI/MDI-X configuration eliminates the confusion of whether to use a straight cable or a crossover cable
between the KSZ8041NL/RNL and its link partner. This feature allows the KSZ8041NL/RNL to use either type of cable to
connect with a link partner that is in either MDI or MDI-X mode. The auto-sense function detects transmit and receive
pairs from the link partner, and then assigns transmit and receive pairs of the KSZ8041NL/RNL accordingly.
HP Auto MDI/MDI-X is enabled by default. It is disabled by writing a one to register 1F bit 13. MDI and MDI-X mode is
selected by register 1F bit 14 if HP Auto MDI/MDI-X is disabled.
An isolation transformer with symmetrical transmit and receive data paths is recommended to support auto MDI/MDI-X.
The IEEE 802.3 Standard defines MDI and MDI-X as follows:
MDI
MDI-X
RJ-45 Pin
Signal
TD+
TD-
RJ-45 Pin
Signal
RD+
RD-
1
2
3
6
1
2
3
6
RD+
RD-
TD+
TD-
Table 5. MDI/MDI-X Pin Definition
September 2010
28
M9999-090910-1.4
MICREL [ MICREL SEMICONDUCTOR ]
