Datasheet

±15kV ESD Protected MII/RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support and flexPWR

Technology in a Small Footprint

Datasheet

SMSC LAN8700/LAN8700i 55 Revision 2.3 (04-12-11)

DATASHEET

5.4.8.2 Far Loopback

Far loopback is a special test mode for MDI (analog) loopback as indicated by the blue arrows in

Figure 5.3. The far loopback mode is enabled by setting bit register 17 bit 9 to logic one. In this mode,

data that is received from the link partner on the MDI is looped back out to the link partner. The digital

interface signals on the local MAC interface are isolated.

Note: This special test mode is only available when operating in RMII mode.

5.4.8.3 Connector Loopback

The LAN8700/LAN8700i maintains reliable transmission over very short cables, and can be tested in

a connector loopback as shown in Figure 5.4. An RJ45 loopback cable can be used to route the

transmit signals an the output of the transformer back to the receiver inputs, and this loopback will

work at both 10 and 100.

Figure 5.3 Far Loopback Block Diagram

Figure 5.4 Connector Loopback Block Diagram

Far-end system

SMSC

Ethernet Transceiver

10/100

Ethernet

MAC

CAT-5

XFMR

Digital

RXD

TXD

Analog

Link

Partner