lxt972a Intel Corporation, lxt972a Datasheet - Page 24

• Manufacturer Part Number: lxt972a
• Description: 3.3v Dual-speed Fast Ethernet Transceiver Datasheet
• Manufacturer: Intel Corporation

LXT972A — 3.3V Dual-Speed Fast Ethernet Transceiver Datasheet
3.5
3.5.1
3.5.1.1
3.5.1.2
24
1. Refer to
Auto-Neg
Disabled
Enabled
Table 8.
Desired Mode
Table 7 on page 15
100 Only
(Mbps)
Speed
10/100
Hardware Configuration Settings
100
Establishing Link
See
Auto-Negotiation
If not configured for forced operation, the LXT972A attempts to auto-negotiate with its link
partner by sending Fast Link Pulse (FLP) bursts. Each burst consists of up to 33 link pulses spaced
62.5 s apart. Odd link pulses (clock pulses) are always present. Even link pulses (data pulses) may
be present or absent to indicate a “1” or a “0”. Each FLP burst exchanges 16 bits of data, which are
referred to as a “link code word”. All devices that support auto-negotiation must implement the
“Base Page” defined by IEEE 802.3 (registers 4 and 5). LXT972A also supports the optional “Next
Page” function as described in
Base Page Exchange
By exchanging Base Pages, the LXT972A and its link partner communicate their capabilities to
each other. Both sides must receive at least three identical base pages for negotiation to continue.
Each side identifies the highest common capabilities that both sides support and configures itself
accordingly.
Next Page Exchange
Additional information, above that required by base page exchange, is also sent via “Next Pages’.
The LXT972A fully supports the IEEE 802.3ab method of negotiation via Next Page exchange.
10
Figure 8
Half Only
Duplex
Full or
Half
Half
Half
Half
Full
Full
Full
for LED/CFG pin assignments.
for an overview of link establishment.
High
High
High
High
Low
Low
Low
Low
1
Pin Settings
LED/CFGn
High
High
High
High
Low
Low
Low
Low
2
High
High
High
High
Low
Low
Low
Low
Table 44
1
3
AutoNeg
0.12
and
0
1
Control Register
Table 45
Speed
0.13
0
1
1
Resulting Register Bit Values
(registers 7 and 8).
FD
0.8
0
1
0
1
0
1
0
1
100FD
Auto-Negotiation Advertisement
4.8
0
1
0
1
Auto-Neg Advertisement
100TX
4.7
1
1
1
1
N/A
10FD
4.6
0
0
0
1
Datasheet
10T
4.5
0
0
1
1