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OPA277: OPA277P - OFFSET TRIM VS OFFSET NULL PIN

ANAND THIRAVIAM
Prodigy 50 points
Part Number: OPA277


Could you clarify the difference between the OPA277P’s two “Offset Trim” pins and a traditional “Offset Null” pin? Specifically, are “offset trim” and “offset null” equivalent terms that can be used interchangeably on schematic symbols, or should the symbol label be more precise to reflect functional or implementation differences? and Could you please confirm whether the offset trim pins are inputs or analog pins, since I can see those pins were considered as inputs in reference designs?

  • 0
    TI__Genius 13825 points

    Hello,

    Yes, generally "Offset Trim" and "Offset Null" are interchangeable.  These are typically connected to a potentiometer, allowing the offset of the amplifier to be "tuned" to zero when the potentiometer is adjusted.  See below:

    If they aren't used, then they should be left floating.  The schematic above looks fine to me.

    Hope this helps,
    Mike

  • 0 in reply to Michael Hartshorne
    Prodigy 50 points

    Thanks for the prompt response, Would you clarify the second part of the question which is " whether the offset trim pins are inputs or analog pins, since I can see those pins were considered as inputs in reference designs?"

  • 0 in reply to ANAND THIRAVIAM
    TI__Genius 13825 points

    Hello,

    I would call them inputs -  they are also analog, this op amp has no digital pins.  Maybe you are thinking of an enable pin - this is not an enable pin, this will use a resistor to divide current sharing across the input pair, not just detect a voltage level.

    Regards,
    Mike