±15kV ESD Protected MII/RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support and flexPWR® Technology in a Small Footprint
Datasheet
Chapter 1 General Description
The SMSC LAN8700/LAN8700i is a low-power, industrial temperature (LAN8700i), variable I/O voltage,
analog interface IC with HP Auto-MDIX support for high-performance embedded Ethernet applications.
The LAN8700/LAN8700i can be configured to operate on a single 3.3V supply utilizing an integrated
3.3V to 1.8V linear regulator. An option is available to disable the linear regulator to optimize system
designs that have a 1.8V power plane available.
1.1
Architectural Overview
The LAN8700/LAN8700i consists of an encoder/decoder, scrambler/descrambler, wave-shaping
transmitter, output driver, twisted-pair receiver with adaptive equalizer and baseline wander (BLW)
correction, and clock and data recovery functions. The LAN8700/LAN8700i can be configured to
support either the Media Independent Interface (MII) or the Reduced Media Independent Interface
(RMII).
The LAN8700/LAN8700i is compliant with IEEE 802.3-2005 standards (MII Pins tolerant to 3.6V) and
supports both IEEE 802.3-2005 compliant and vendor-specific register functions. It contains a full-
duplex 10-BASE-T/100BASE-TX transceiver and supports 10-Mbps (10BASE-T) operation on
Category 3 and Category 5 unshielded twisted-pair cable, and 100-Mbps (100BASE-TX) operation on
Category 5 unshielded twisted-pair cable.
10/100
Media
Access
Controller
(MAC)
Magnetics
Ethernet
SMSC
LAN8700/
LAN8700i
System Bus
LEDS/GPIO
MII /RMII
or SOC
25 MHz (MII) or 50MHz (RMIII)
Crystal or External Clock
Figure 1.1 LAN8700/LAN8700i System Block Diagram
Hubs and switches with multiple integrated MACs and external PHYs can have a large pin count due
to the high number of pins needed for each MII interface. An increasing pin count causes increasing
cost.
The RMII interface is intended for use on Switch based ASICs or other embedded solutions requiring
minimal pincount for ethernet connectivity. RMII requires only 6 pins for each MAC to PHY interface
plus one common reference clock. The MII requires 16 pins for each MAC to PHY interface.
The SMSC LAN8700/LAN8700i is capable of running in RMII mode. Please contact your SMSC sales
representative for the latest RMII specification.
The LAN8700/LAN8700i referenced throughout this document applies to both the commercial
temperature and industrial temperature components. The LAN8700i refers to only the industrial
temperature component.
Revision 2.3 (04-12-11)
8
SMSC LAN8700/LAN8700i
DATASHEET
SMSC [ SMSC CORPORATION ]
