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ADV8005 and ADN4654 for Galvanic Isolation


We need to implement galvanic isolation in video equipment with VGA, CVBS and DVI input interfaces.

The following diagram shows one of our approaches.


Although the input image may be at 1920x1080p60 (Full HD), it will be converted to 1280x720p60 (HD) in the NVIDIA TX2 processor before being recorded.

So we plan to use ADV8005 do downscale it by HW, enabling the use of ADV4654 to isolate the TMDS interface. Otherwise, it would not handle the 1.49 Gbit/s data rate at Full HD.

In this application, ADV8005 would not need external DDR2 memory. It would only be configured to perform either downscaling when we receive Full HD images or bypass when we receive HD.

Can you please validate this approach?

Can you also provide a reference script for the configuration we need?

Any other ideas/suggestions are much appreciated.

Thank you.

  • Hi,

     Please let me clarify one thing, why we want to isolate TMDS interface b/w ADV8005 and ADV7482. Since ADV7482 can handle full HD format, its maximum pixel clock frequency is 162 MHz .

     ADV8005: Using External DDR only, we can support scaling in ADV8005, Since External DDR2 memory is required for motion adaptive de-interlacing, scaling(UP-Scale/Down-Scale), frame rate conversion,  and bitmap OSD overlay.

     Please refer here for Evaluation software of ADV8005

     As per expert comment  "For evaluation of ADV8003, We should definitely use the SW driver, then if you want to port our SW driver to run on your microprocessor, you will need to do an SLA". Your ADI sales contact or distributor should be able to help with that.



  • Hi Poornima.

    This isolation is necessary to meet regulatory safety requirements (this video recording solution will be connected to electromedical equipment).

    We have a working prototype where we implemented the isolation in the Pixel bus using this chain: [7842 + Isolators + TFP410 + 7482]. Due to the possibility of timing issues (channel and part-to-part skew) we plan to change to this new approach of using [7842 + 8005 + Isolator + 7482]. However, there's no BW in the isolator to handle Full HD at TMDS.

    Full HD is required at the Input (since it comes from a laparoscopic camera) but not for recording. So we can downscale it by HW.

    As for the external memory, pg. 104 of the HW Ref. Manual states:

    "While the SVSP uses external DDR2 memory for the majority of operations, in the case of down converting from 1080p to 720p (with the same frame rate), no external memory is required and all conversions can take place in internal line

    Pg. 151 also shows:

    " DDR Bypass Mode
    In the case where the SVSP is being used to upscale or downscale between 1080p and 720p, external DDR2 memory is not required. Internal line buffers allow the user to convert between these two resolutions while maintaining the full external memory bandwidth for both the PVSP and OSD."

    We only need to convert 1920x1080p60 to 1280x720p60.

    ADV8005 will be used just for this and will be either in bypass mode (when the input is already in HD) or doing this downscaling (when the input is Full HD).

    Regarding SW, all we need is a couple of register configurations to put ADV8005 either in bypass or downscaling. We will use some short scripts for this and no driver is needed.

    Do you see any issues? Am I missing something?

  • Hi,

     Yes you are right, In the case of down converting from 1080p to 720p (with the same frame rate), no external memory is required.

    As per Expert comment about ADV8005 script  "You can easily change the device address in the source code.  We do not supply plain scripts for the ADV8005".



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