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SN10501: Video Op-Amp not operating properly as a voltage follower

Mathew Kraemer
Prodigy 10 points
Part Number: SN10501

Hi,

I'm running into issues where the SN10501DBVT isn't buffering the input correctly. The input signal range is 0v-1.4v, running at around 25.2MHz at max and the op-amp is powered via 3.3v.

Attached are some screenshots of scope captures and layout/schematic.

Input

Output

Thanks

  • +1
    Guru 140200 points

    Hi Matthew,

    according to the datasheet the input signal must stay 1.1V away from the supply rails. So the allowed input voltage range would be 1.1V...2.2V, but not 0V...1.4V.

    Kai

  • +1
    TI__Genius 11385 points

    Hello Matthew,

    Kai is absolutely correct here: in order to properly observe the input common mode voltage range operating condition, the input signal must be 1.1V away from both supply rails.  In a single-supply configuration like your circuit, this means your lowest voltage of your input signal must not go below 1.1V.  If this occurs, distortion and unwanted signal behavior are certain to be observed.

    Please continue to ask questions for ways to resolve this behavior or other design considerations.

    Best,

    Alec

  • 0
    Prodigy 10 points

    Thanks for the help! I missed that part of the datasheet. I saw rail to rail and assumed it'd be fine and forgot to double check it.

    I'll go back and make those changes.

    Thanks,

    Matt