LXT9763 — Fast Ethernet 10/100 Hex Transceiver with Full MII
The LXT9763 does not support fiber connections at 10 Mbps.
1.11.1
10T Preamble Handling
The LXT9763 offers two options for preamble handling, selected by bit 16.5. In 10T Mode when
16.5 = 0, the LXT9763 strips the entire preamble off of received packets. CRS is asserted
coincident with SFD. RX_DV is held Low for the duration of the preamble. When RX_DV is
asserted, the very first two nibbles driven by the LXT9763 are the SFD “5D” hex followed by the
body of the packet.
In 10T mode with 16.5 = 1, the LXT9763 passes the preamble through the MII and asserts RX_DV
and CRS simultaneously. In 10T loopback, the LXT9763 loops back whatever the MAC transmits
to it, including the preamble.
1.11.2
1.11.3
1.11.4
10T Carrier Sense
For 10T links, CRS assertion is based on reception of valid preamble, and de-assertion on reception
of an end-of-frame (EOF) marker. Bit 16.7 allows CRS de-assertion to be synchronized with
RX_DV de-assertion. Refer to Table 47 on page 68.
10T Dribble Bits
The LXT9763 device handles dribbles bits in all modes. If between 1-4 dribble bits are received,
the nibble is sent across the MII, padded with 1s if necessary. If between 5-7 dribble bits are
received, the second nibble is not sent onto the MII bus.
10T Link Test
In 10T mode, the LXT9763 always transmit link pulses. If the Link Test function is enabled, it
monitors the connection for link pulses. Once link pulses are detected, data transmission will be
enabled and will remain enabled as long as either the link pulses or data transmission continue. If
the link pulses stop, the data transmission will be disabled.
If the Link Test function is disabled (Force Link Pass), the LXT9763 will transmit to the
connection regardless of detected link pulses. The Link Test function can be disabled by setting bit
16.14 = 1.
1.11.4.1
Link Test Failure
Link Test failure occurs if Link Test is enabled and link pulses or packets stop being received. If
this condition occurs, the LXT9763 returns to the auto-negotiation phase if auto-negotiation is
enabled.
10T Jabber
If a transmission exceeds the jabber timer, the LXT9763 will disable the transmit and loopback
functions. See 29 on page 55 for jabber timing parameters.
The LXT9763 automatically exits jabber mode after the unjab time has expired. This function can
be disabled by setting bit 16.10 = 1.
34
Datasheet
INTEL [ INTEL ]
