Non-PCI Single-Chip Full Duplex Ethernet Controller
9.9
Network Interface
The LAN91C96I includes both an AUI interface for thick and thin coax applications and a 10BASE-T
interface for twisted pair applications. Functions common to both are:
1. Manchester encoder/decoder to convert NRZ data to Manchester encoded data and back.
2. A 32ms jabber timer to prevent inadvertently long transmissions. When 'jabbing' occurs, the
transmitter is disabled, automatic loopback is disabled (in 10BASE-T mode), and a collision indication
is given to the controller. The interface 'unjabs' when the transmitter has been idle for a minimum of
256 ms.
3. A phase-lock loop to recover data and clock from the Manchester data stream with up to plus or minus
18ns of jitter.
4. Diagnostic loopback capability.
5. LED drivers for collision, transmission, reception, and jabber.
9.10 10BASE-T
The 10BASE-T interface conforms to the twisted pair MAU addendum to the 802.3 specification. On the
transmission side, it converts the NRZ data from the controller to Manchester data and provides the
appropriate signal level for driving the media. Signal are predistorted before transmission to minimize ISI.
The collision detection circuitry monitors the simultaneous occurrence of received signals and transmitted
data on the media. During transmission, data is automatically looped back to the receiver except during
collision periods, in which case the input to the receiver is network data. During collisions, should the
receive input go idle prior to the transmitter going idle, input to the receiver switches back to the transmitter
within nine bit times. Following transmission, the transmitter performs a SQE test. This test exercises the
collision detection circuitry within the 10BASE-T interface.
The receiver monitors the media at all times. It recovers the clock and data and passes it along to the
controller. In the absence of any receive activity, the transmitter is looped back to the receiver. In addition,
the receiver performs automatic polarity correction. The 10BASE-T interface performs link integrity tests
per section 14.2.1.7 of 802.3, using the following values:
1. Link_loss_timer: 64 ms
2. Link_test_min_timer: 4 ms
3. Link_count: 2
4. Link_test_max_timer: 64 ms
The state of the link is reflected in the EPHSR.
9.11 AUI
The LAN91C96I also provides a standard six wire AUI interface to a coax transceiver.
SMSC DS – LAN91C96I
Page 79
Rev. 11/18/2004
DATASHEET
SMSC [ SMSC CORPORATION ]
