lxt971a Intel Corporation, lxt971a Datasheet - Page 36

• Manufacturer Part Number: lxt971a
• Description: 3.3v Dual-speed Fast Ethernet Phy Transceiver
• Manufacturer: Intel Corporation

LXT971A 3.3V Dual-Speed Fast Ethernet Transceiver
3.7
3.7.1
36
Table 10. Carrier Sense, Loopback, and Collision Conditions
Figure 14. 100BASE-X Frame Format
100 Mbps Operation
100BASE-X Network Operations
During 100BASE-X operation, the LXT971A transmits and receives 5-bit symbols across the
network link.
actively transmitting data, the LXT971A sends out Idle symbols on the line.
In 100BASE-TX mode, the LXT971A scrambles and transmits the data to the network using MLT-
3 line code
decoded, and sent across the MII to the MAC.
In 100BASE-FX mode, the LXT971A transmits and receives NRZI signals across the LVPECL
interface. An external 100FX transceiver module is required to complete the fiber connection. To
enable 100BASE-FX operation, auto-negotiation must be disabled and FX selected.
100 Mbps
10 Mbps
1. Test Loopback is enabled when 0.14 = 1
Speed
Replaced by
/J/K/ code-groups
Start-of-Stream
Delimiter (SSD)
P0
64-Bit Preamble
P1
(8 Octets)
(Figure 15 on page
Full-Duplex
Half-Duplex
Full-Duplex
Half-Duplex,
Register bit 16.8 = 0
Half-Duplex,
Register bit 16.8 = 1
Duplex Condition
Figure 14
P6
Delimiter (SFD)
Start-of-Frame
SFD
shows the structure of a standard frame packet. When the MAC is not
DA
Address (6 Octets each)
Destination and Source
DA
37). MLT-3 signals received from the network are de-scrambled,
Receive Only
Transmit or Receive
Receive Only
Transmit or Receive
Transmit or Receive
SA
Carrier Sense
SA
Packet Length
L1
(2 Octets)
L2
Loopback
(Pad to minimum packet size)
Test
D0
Yes
Yes
Yes
No
No
Data Field
1
D1
Operational
Loopback
Dn
Yes
No
No
No
No
Frame Check Field
(4 Octets)
CRC
End-of-Stream Delimiter (ESD)
Rev. Date: August 7, 2002
/T/R/ code-groups
None
Transmit and Receive
None
Transmit and Receive
Transmit and Receive
Replaced by
InterFrame Gap / Idle Code
I0
Document #: 249414
Collision
(> 12 Octets)
Revision #: 002
Datasheet
IFG