VSC7140 Datasheet, PDF (3/12 Pages) Vitesse Semiconductor Corporation – 1.0625 Gb/s Fibre Channel Dual Repeater / Hub Node

Data Sheet
VSC7140
VITESSE
SEMICONDUCTOR CORPORATION
1.0625 Gb/s Fibre Channel
Dual Repeater / Hub Node
Application Examples
The VSC7140 is intended for two applications, Dual Repeater or Dual Hub, as configured by HUB. Users
needing to retime both incoming and outgoing signals at the bulkhead of a Fibre Channel system would use the
part in Dual Repeater Mode (HUB is LOW). Users building Fibre Channel Hubs would use the part in Dual
Hub mode (HUB is HIGH) to fully handle the functions of two Hub Nodes.
Dual Repeater Mode
In this example, the VSC7140 forms a dual repeater in a complex Fibre Channel system, such as a JBOD
(Just a Bunch Of Disks) RAID (Redundant Array of Independent Disks) subsystem, which requires the incom-
ing Fibre Channel signal to be retimed to ensure adequate signal quality to the input of the subsystem. Like-
wise, the output of the JBOD subsystem requires retiming to ensure that the outgoing signal from the system
meets the amplitude and jitter requirements of Fibre Channel. For this application, the dual CRUs are the only
circuits required although the SDUs may be used for reporting signal status. Therefore, the VSC7140 would be
configured as follows:
HUB is LOW to select Dual Repeater Mode.
RX1 connects to the external input from the bulkhead.
SO1 connects to the input to the JBOD subsystem.
RX2 connects to the output of the JBOD subsystem.
SO2 connects to the output to the bulkhead.
SI1 and SI2 are not used. Pull up SI1+ and SI2+ to V_DD with 22k Ohms to prevent input oscillations.
TX1 and TX2 are not used. Leave unconnected.
SEL1 and SEL2 are driven HIGH.
FAIL1- and FAIL2- may be used for status. ERRSEL is selected as desired by the user.
Figure 1: Block Diagram: Use of VSC7140 in Dual Repeater Mode
VSC7140
RX1 _CRU SO1
SO2 _CRU RX2
Internal
Fibre Channel
Subsystem
G52180-0, Rev 4.0
10/23/00
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