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Buffer TFP401/403 outputs?

George Ioakimedes
Genius 4950 points
Other Parts Discussed in Thread: TFP401, TFP403, SN75LVDS83B, SN74CBT34X245

I'm looking at making a board which will have a single LVDS output using the SN75LVDS83B. The input to the SN75LVDS83B can either come from a TFP401 (or TFP403, I haven't decided) OR from the 24-bit output from an OMAP processor.

I would allow only 1 input set to be active at 1 time but should I buffer the inputs before the SN75LVDS83B, and if so what would be a good part?

The block diagram looks something like this:

 

DVI -----> TFP401 -->

                                   |

                                       ---------> SN75LVDS83B -------> LVDS Connector

                                   |

OMAP RGB888  --->

 

Thanks,

George

  • 0
    TI__Genius 11320 points

    The TFP401/403 will place the outputs in a hi-z state when the device is placed in PD mode.  I'll defer to others regarding the OMAP output and SN75LVDS83B input requirements.

  • 0 in reply to Undrea Fields
    TI__Genius 11280 points

    George:

    You can use a couple of 32-bit FET bus switch, like the SN74CBT32245 or SN74CBT34X245 (figure 1) or maybe you could use a CPLD and build inside a "n" bit 2-to-1 digital multiplexer (figure 2). Propagation delay offsets are need to be added into overall system setup and hold.

    Best regards,

    Gerardo

     

  • 0 in reply to Gerardo
    Genius 4950 points

    If the TFP401/3 places their outputs in Hi-Z then I'm not sure if a switch would be necessary. I'm concerning with signal integrity of the video signals coming out of the OMAP since designing like this is going to create stubs. My final design idea is to use an FPGA to offer complete flexibility but I wanted to try a less "complicated" design first.

    Perhaps I need post this in the OMAP section to get some feedback there?