adm6995 ETC-unknow, adm6995 Datasheet - Page 21

• Manufacturer Part Number: adm6995
• Description: Port 10/100 Mb/s Single Chip Ethiernet Switch Controller
• Manufacturer: ETC-unknow

ADM6995L
ADMtek Inc.
3.5
3.4.11
3.4.12
3.5.1
A bad start of stream delimiter (Bad SSD) is an error condition that occurs in the
100Base-X receiver if carrier is detected (CRS asserted) and a valid /J/K set of code-
group (SSD) is not received.
If this condition is detected, then the ADM6995L will assert RXER and present
RXD[3:0] = 1110 to the internal MII for the cycles hat correspond to received 5B code-
groups until at least two idle code-groups are detected. Once at least two idle code groups
are detected, RXER and CRS become de-asserted.
Auto negotiation provides a mechanism for transferring information from the Local
Station to the link Partner that a remote fault has occurred for 100Base-TX. As auto
negotiation is not currently specified for operation over fiber, the far end fault indication
function (FEFI) provides this capability for 100Base-FX applications.
A remote fault is an error in the link that one station can detect while the other cannot. An
example of this is a disconnected wire at a station’s transmitter. This station will be
receiving valid data and detect that the link is good via the link integrity monitor, but will
not be able to detect that its transmission is not propagating to the other station.
A 100Base-FX station that detects such a remote fault may modify its transmitted idle
stream from all ones to a group of 84 ones followed by a single 0. This is referred to as
the FEFI idle pattern.
100Base-TX Transceiver
ADM6995L implements a TP-PMD compliant transceiver for 100Base-TX operation.
The differential transmit driver is shared by the 10Base-T and 100Base-TX subsystems.
This arrangement results in one device that uses the same external magnetic for both the
10Base-T and the 100Base-TX transmission with simple RC component connections.
The individually wave-shaped 10Base-T and 100Base-TX transmit signals are
multiplexed in the transmission output driver selection.
The ADM6995L 100Base-TX transmission driver implements MLT-3 translation and
wave-shaping functions. The rise/fall time of the output signal is closely controlled to
conform to the target range specified in the ANSI TP-PMD standard.
Bad SSD Detection
Far-End Fault
Transmit Drivers
Function Description
3-5