When operating in CSI-2 FPD-Link III input mode (with DS90UB953-Q1 or DS90UB935-Q1), the DS90UB954-Q1 receives CSI-2 formatted data on one or two FPD-Link III input ports and forwards the data to the CSI-2 transmit port. The deserializer can operate in CSI-2 mode with synchronous back channel reference or non-synchronous mode. The forward channel line rate is independent of the CSI-2 rate in synchronous or non-synchronous with external clock mode. Each CSI-2 mode supports remapping of Virtual Channel IDs at the input of each receive port. This allows handling of conflicting VC-IDs for input streams from dual sensors and sending those streams to the same CSI-2 transmit port.

In CSI-2 mode each deserializer Rx Port can support an FPD-Link line rate up to 4.16 Gbps, where the forward channel and back channel rates are based on the reference frequency used for the serializer:

• In Synchronous mode based on REFCLK input frequency reference, the FPD-Link line rate is a fixed value of 160 × REFCLK. FPD3_PCLK = 4 × REFCLK and Back channel rate = 2 × REFCLK. For example with REFCLK = 25 MHz, line rate = 4.0 Gbps, FPD3_PCLK = 100 MHz, back channel data rate = 50 Mbps. The sensor CSI-2 rate is independent of the line rate and Tx CSI-2 rate in synchronous clocking mode and can be up to 3.328 Gbps.
• In Non-synchronous clocking mode when the DS90UB953-Q1 or DS90UB935-Q1 uses external reference clock (f_CLKIN) the FPD-Link line rate is typically f_CLKIN × 80, FPD3_PCLK = 2 × f_CLKIN or 1 x f_CLKIN and back channel data rate is set to 10 Mbps. For example, with f_CLKIN = 50 MHz, line rate = 4Gbps, FPD3_PCLK = 100 MHz, and the back channel rate is 10 Mbps. The sensor CSI-2 rate is independent of the f_CLKIN.