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> 6 pc. vitesse# VSC7122QM, 1.0625 gb/s fibre channel arb
6 pc. vitesse# VSC7122QM, 1.0625 gb/s fibre channel arb
The following item has just been added to our store in a larger qty. This item is for 6 pcs. only!
Quad port bypass circuit for 1.0625 Gb/s fibre channel arbitrated loop disk arrays. 3.3 power supply
The VSC7122 is a Quad Port Bypass Circuit (PBC). Four Fibre Channel PBC s are cascaded into a single
part to minimize part count, cost, high frequency routing, and jitter accumulation. Port Bypass Circuits are used
to provide resiliency in Fibre Channel Arbitrated Loop (FC-AL) architectures. PBC s are used within FC-AL
disk arrays to allow for resiliency and hot swapping of FC-AL drives.
A Port Bypass Circuit is a 2:1 Multiplexer with two modes of operation: NORMAL and BYPASS. In NORMAL
mode, the disk drive is connected to the loop. Data goes from the 7122 s L_SOn pin to the Disk Drive RX
input and data from the disk drive TX output goes to the 7122 s L_SIn pin. Refer to Figure 2 for disk drive
application. In BYPASS mode, the disk drive is either absent or non-functional and data bypasses to the next
available disk drive. Normal mode is enabled with a HIGH on the SEL pin and BYPASS mode is enabled by a
LOW on the SEL pin. Direct Attach Fibre Channel Disk Drives have an LRC Interlock signal defined to control
Using a VSC7122 in a single loop of a disk array is illustrated in Figure 2: Disk Array Application . FCAL
drives are all expected to be dual loop. The VSC7122 is cascaded in a manner such that all the 7122 s internal
PBC s are used in the same loop. For dual loop implementations, two or more VSC7122 s should be used.
Allocating each VSC7122 to only one of two loops preserves redundancy, prevents a single point of failure and
lends itself to on-line maintainability.
The VSC7122 is very similar to the VSC7121 except that LSO+ outputs are all full power outputs identical
to OUT. This is useful in passive backplanes to provide additional amplitude on long traces.
Supports ANSI X3T11 1.0625 Gbit/sec
FC-AL Disk Attach for Resiliency
Fully Differential for Minimum
Quad PBC s in Single Package
High Speed, PECL I/O s Referenced to V
0.35W Typical Power Dissipation
