VSC7121

www.DataSheet4U.com VITESSE SEMICONDUCTOR CORPORATION Data Sheet VSC7121 Description Supports ANSI X3T11 1.0625 Gbit/sec FC-AL Disk Attach for Resiliency Fully Differential for Minimum Jitter Accumulation. Quad PBC’s in Single Package Quad Port Bypass Circuit for 1.0625 Gbit/sec Fibre Channel Arbitrated Loop Disk Arrays TTL Bypass Select High Speed, PECL I/O’s Referenced to VDD. 0.5W Typical Power Dissipation 3.3V Power Supply 44-Pin, 10mm PQFP The VSC7121 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 7121’s L_SOn pin to the Disk Drive RX input and data from the disk drive TX output goes to the 7121’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 the...