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OPA693 Video 1-input 2-output

Other Parts Discussed in Thread: OPA693

Hello!

On the first page of the datasheet for the OPA693, there is an example of a 700MHz, 2-Output Component Video DA circuit.  

My question is if I apply single +5V supply (i.e. pin 4 [-Vs] will be connected to GND) instead of the dual supply in the example, will the circuit still behave the same?

I'm looking into splitting a video input to two outputs, so was wondering if the referenced circuit here will produce the desired effect in my application.

Thank you very much.  Your support is appreciated!

Best Regards,

Kenneth

  • Hello Kenneth,
    On single supply applications, the circuit above will work, however you have to take into account the input common-mode and output swing limitations. The datasheet has spec'ed the 5V single-supply performance, however everything was done with a 2.5V reference.
    On the input side: From page 5 of the datasheet, INPUT section, the common-mode range will extend from 1.6V to 3.4V. On the input side, remember that the 75Ohm termination from "Video In" will be to 2.5V for a single-supply operation. (Not GND)

    On the output side:From page 5 of the datasheet, OUTPUT section, the output swing range will extend from 1.1V to 3.9V with 100Ohm load. On the output side, the two 75Ohm load resistors at "Video Out" will be to 2.5V for a single-supply operation. (Not GND)

    As long as you can satisfy these requirements you will be fine.

    -Samir
  • Also keep in mind that by doing as Samir suggests, the output is no longer "ground referenced" but offset by +2.5 . If the device that the video signal is connecting to is expecting a ground referenced signal you may have a problem. A capacitor to block the DC is required; calculate the value for the frequency you are going to process.

    Mike T.