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The CBTU0808 is a dual lane port multiplexer designed to provide convenient and reliable path switching for PCI Express signals. It is organized as two PCI Express lanes, each consisting of a Transmit and Receive channel. Each channel has four ports, two (A and B) on the source (or host) side and two (A and B) on the destination (or device) side. Each port provides a pair of signal lines to support PCIe differential signaling.
Using specially designed high-bandwidth and high off-isolation switch elements, source and destination ports can be connected or isolated in three possible configurations: source A and B to destinations A and B respectively; or source A to destination B (remaining ports isolated), or all ports isolated.
The switch elements are controlled by internal control logic to set switch positions in accordance with these three configurations, selectable by CMOS inputs CTRL0 and CTRL1 for lanes 0 and 1 respectively. Within a lane, the switch configuration is always applied identically to both transmit and receive channels.
The CBTU0808 is packaged in a 48-ball, depopulated 9 x 9 grid, 0.5 mm ball pitch, thin profile fine-pitch ball grid array (TFBGA) package, which (while requiring a minimum 5 mm x 5 mm of board space) allows for adequate signal routing and escape using conventional board technology.