80220 Datasheet, PDF (22/91 Pages) LSI Computer Systems – 100BASE-TX/10BASE-T Ethernet Media Interface Adapter

80220/80221
3.13 LINK INTEGRITY & AUTONEGOTIATION
3.13.1 General
The 80220/80221 can be configured to implement either
the standard link integrity algorithms or the AutoNegotiation
algorithm.
The standard link integrity algorithms are used solely to
establish an active link to and from a remote device. There
are different standard link integrity algorithms for 10 and
100 Mbps modes. The AutoNegotiation algorithm is used
for two purposes: (1) To automatically configure the device
for either 10/100 Mbps and Half/Full Duplex modes, and
(2) to establish an active link to and from a remote device.
The standard link integrity and AutoNegotiation algorithms
are described below.
3.13.2 10Base-T Link Integrity Algorithm - 10Mbps
The 80220/80221 uses the same 10Base-T link intergrity
algorithm that is defined in IEEE 802.3 Clause 14. This
algorithm uses normal link pulses, referred to as NLP's and
transmitted during idle periods, to determine if a device
has successfully established a link with a remote device
(called Link Pass state). The transmit link pulse meets the
template defined in IEEE 802.3 Clause 14 and shown in
Figure 7. Refer to IEEE 802.3 Clause 14 for more details
if needed.
0 BT
3.1 V
1.3 BT
3.13.3 100Base-TX Link Integrity Algorithm -100Mbps
Since 100Base-TX is defined to have an active idle signal,
then there is no need to have separate link pulses like
those defined for 10Base-T. The 80220/80221 uses the
squelch criteria and descrambler synchronization algo-
rithm on the input data to determine if the device has
successfully established a link with a remote device (called
Link Pass state). Refer to IEEE 802.3 for both of these
algorithms for more details.
3.13.4 AutoNegotiation Algorithm
As stated previously, the AutoNegotiation algorithm is
used for two purposes: (1) To automatically configure the
device for either 10/100 Mbps and Half/Full Duplex modes,
and (2) to establish an active link to and from a remote
device. The AutoNegotiation algorithm is the same algo-
rithm that is defined in IEEE 802.3 Clause 28.
AutoNegotiation uses a burst of link pulses, called fast link
pulses and referred to as FLP's, to pass up to 16 bits of
signaling data back and forth between the 80220/80221
and a remote device. The transmit FLP pulses meet the
templated specified in IEEE 802.3 and shown in Figure 7.
A timing diagram contrasting NLP's and FLP's is shown in
Figure 8.
585 mV
0.5 V/ns
0.5 BT
0.6 BT
+50 mV
–50 mV
0.25 BT
2.0 BT
300 mV
4.0 BT
200 mV
4.0 BT
42.0 BT
+50 mV
–50 mV
MD400159/E
–3.1 V
0.85 BT
2.0 BT
Figure 7. Link Pulse Output Voltage Template _ NLP, FLP
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