Repeater/Retimer & PBCs Are On Fibre Channel Storage Chip

The VSC7127 chip packs five integrated Port Bypass Circuits (PBCs) and is said to be the Fibre Channel industry's first to offer repeater and retimer modes for use by makers of JBODs and disk arrays. The device allows for the configuration of the integrated clock recovery unit (CRU) as a repeater or a retimer via a mode pin to give existing designs the benefits of both modes of operation without re-design. In repeater mode, recovered data is retransmitted to the recovered clock, allowing jitter attenuation and low latency. The propagation delay in repeater mode is less than 7 ns. In retimer mode, recovered data is retransmitted synchronously to a local reference clock with no jitter transfer. In this mode, the propagation delay is 180 ns maximum and all input jitter is eliminated. Fibre Channel ordered sets are added or dropped to accommodate any speed mismatch between the recovered clock and the local clock. Typical retimer output total jitter is less than 60 ps pk-pk. The five PBCs allow for connection of multiple Fibre Channel disk drive systems, while providing superior signal quality. Additional features are A/D signal detect and on-chip transmit termination that eliminates the need for external components on the transmit side.