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unused op amp

Discussion in 'General Electronics Discussion' started by jfk, Apr 4, 2016.

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  1. jfk

    jfk

    13
    1
    Mar 28, 2016
    I have a an unused channel of an MCP6002 op amp in my working design.
    I've heard that leaving it open might cause latch up or noise.

    Analog Designs say to tie output to inverting input, and then non inverting input to "a potential between the rails". I assume they mean to add a couple of like resistors.

    In practical terms, do I need to do this? It's two more parts..
     
  2. hevans1944

    hevans1944 Hop - AC8NS

    4,378
    2,046
    Jun 21, 2012
    It is always wise to follow device manufacturers "suggestions" when attempting to apply their product. Presumably they know more than you do, even if they don't respect the need to save big bux and precious PCB real-estate by eliminating two resistors. If you buy this part from Microchip, their datasheet offers an alternative method: connect the unused non-inverting input to Vdd and the inverting input to common. No resistors needed, but it does draw more power. See 4.5 Unused Op Amps, Figure 4-5, here on page 14 of the Microchip datasheet. They offer this for quad op-amp packages, but it probably also applies to dual op-amp packages as well.

    If in doubt, I would call Microchip, or whichever manufacturer makes your MCP6002, and ask them.
     
  3. jfk

    jfk

    13
    1
    Mar 28, 2016
    I'm okay with a bit more power, so this is a very good solution.
    I should have looked at this specific datasheet.

    Thanks very much.
     
    hevans1944 likes this.
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