AL2100-DS00-R datasheet(15/52 Pages) BOARDCOM

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Preliminary Data Sheet

AL2100

11/11/02

Broa d c om Co rp o r a ti o n

Document

AL2100-DS01-405-R

Fault Propagation

Page 7

Fiber Transmit Link Failure

In the event of a fiber-transmit-link failure, the far-end transceiver, with remote fault signaling capability, transmits the RF

signal to the AL2100. As a result, the AL2100 performs two tasks: ceases to transmit an idle signal to the TP driver, and puts

the driver into high-impedance mode,de-asserting the DATA_OFF signal.

REDUNDANT FUNCTION

FAULT_OUT = DATA_ENABLE && !FX_LINK;

The logic above uses the TP_RCVR_ACTIVE signal to gate the FX output. When the TP receiver is disconnected, it forces

the FX side to drop the link, and causes the TP at the remote side to drop the link as well. When both sides receive activity

in the TP side, the FX port on each side is enabled, and the link-up occurs. The link status of the FX port enables the TP

output, and causes them to link up. The FX remote fault condition is generated by the standard FEF_DETECT state machine.

Three timers generate the TP_RCVR_ACTIVE signal. The first one is the activity_timer; the second one is the link_up_timer;

the third is the tx_disable_timer. When using the activity_timer to determine whether there is a signal on the wire, start the

link_up_timer, and wait for the AN to complete. If the link_up_timer expires, start the tx_disable_timer, and disable

FX_OUPUT_EN and TX_OUTPUT_EN for a predefined period of time. See Figure 3 for more details.

Figure 3: State Machine for Redundant Function

TP_Quite

Wait_ For_Link

Start

Link_Up_Timer

Link_Disable

Start TX_Disable_Timer

TP_Link_Up

Idle

Activity_Timer

_Reset

Link_Up_Timer_Done &&

!TP_LINK_UP ||

Activity_Timer_Done

TP_LINK_UP

!TP_LINK_UP

!Activity_Timer_Done

TX_Disable_Timer_Done

Reset

Link_Pulse || Sigdet

AL2100-DS00-R Datasheet(PDF) 15 Page - Broadcom Corporation.

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