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VSC7142 Dual Repeater/Retimer for Fibre Channel and Gigabit Ethernet

VSC7142

The VSC7142 contains two FibreTimer Repeater /Retimer

cells and Signal Detect Units (SDUs) primarily used for

bidirectional signal clean up applications. Each FibreTimer

cell contains an all-digital clock recovery unit which can be

configured as either a Repeater or a Retimer. Repeaters

recover the incoming signal and retransmit the data

synchronously to the recovered clock in order to attenuate jitter so that downstream

devices see high amplitude, low jitter signals. Retimers eliminate jitter transfer by

retiming the recovered data to the local reference clock. An add/ drop FIFO inserts or

deletes 40-bit Fibre Channel Fill Words to match the incoming data rate to the local

reference clock, thereby ensuring Fibre Channel compliance at the output of the

Retimer. The VSC7142 also operates as a Repeater for Gigabit Ethernet applications at

1.25 Gb/s. Retimer mode is not available for Gigabit Ethernet applications.

MUL TI-NODE SWITCH APPLICA TION:

One application for the VSC7142 is in high port-count Fibre Channel and Ethernet

systems, such as switches. The following diagram shows a switch with a CMOS

protocol ASIC with integrated Serializer/Deserializers (SerDes) located on the Switch

Fabric card. Serial data from the protocol ASIC passes through multiple connectors

and long traces on the PCB before reaching the connector. Without the VSC7142, the

signal quality at the connectors would result in poor system performance. However,

by using the VSC7142, signal quality is ensured to meet the specifications of Fibre

Channel standards at the system interface connectors.

GENERAL DESCRIPTION:

Fibre Channel Switch

Switch ASIC

Switch Fabric Card

Li ne Card

C onnectors

VSC7142

Backplane

Port 1

FibreTimer0 >

< FibreTimer1

Port N