Ethernet Interface Design Considerations
Electrical Specification
Copyright © 2002 Marvell
CONFIDENTIAL
Doc. No. MV-S300165-00, Rev. A
May 21, 2002, Preliminary
Document Classification: Proprietary Information
Page 135
Figure 81: RMII Interface Connection:
17.2 Electrical Specification
The TTL signal levels are compatible with devices operating at a nominal supply voltage of either 3.3V or 5.0V. To
allow interfacing of 3.3V devices and 5.0V devices, all inputs can tolerate input potentials of 5.5V.
17.3 Termination Topology
The MII and RMII specifications do not require terminations. Nonetheless, it is recommended to simulate the
board topology to make sure terminations are not needed.
Additionally, the MII/RMII interface I/O pads are very weak and, in most cases, do not need termination.
Note
If the electrical length of the circuit board traces used to implement these links exhibit transmission line
effects, some form of termination may be required.
17.4 Timing Requirements
and
shows the required AC timings for the RMII specifications and for the GT-64260A RMII
interfaces.
Note
The AC timing might be updated in the RMII specification or in the GT-64260A datasheet. Make sure you
have the most update documents. For every conflict between this document and the specifications
MTxEN
MTxD0[1:0]
CRS_DV
MRxD0[1:0]
REF_CLK
TX_EN
TXD[1:0]
CRS_DV
RXD[1:0]
REF_CLK
RX_ER*
OSC
GT-64260A
PHY