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Connecting Op-Amps

  1. Jul 28, 2011 #1
    Hello,

    I am sure this is a dumb question, but I am not sure about the answer, so hopefully someone can help me.

    I am using an op-amp in a unity gain configuration between a voltage divider and an Arduino development board. Now, I will be connecting the Vcc+ to +5V, but is it okay to connect the Vcc- pin to ground, or would this cause me any issues?

    Thanks ina advance.

    Seán
     
  2. jcsd
  3. Jul 28, 2011 #2
    Should be ok as long as all you need is positive voltages. Your output range will be ~5V to 0V.
     
  4. Jul 28, 2011 #3
    Hello.

    Thanks for the reply.

    Yea, all I need is positive voltages. So, if it is okay to connect it up like that, I guess something else is screwing up my results.

    Well, at least I have crossed one thing off my list.

    Thanks again.

    Seán
     
  5. Jul 28, 2011 #4

    berkeman

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    Staff: Mentor

    You need to use special opamps to run between just 5V and 0V. Simple jellybean opamps like the LM741 and TL084 need several volts of headroom at their inputs and outputs, with respect to the voltage rails. Check the datasheet for the opamp you plan to use.

    There are more advanced CMOS opamps that can have their inputs and outputs operate near the rails. You can search at Maxim or National Semiconductor's websites to find some examples. Just look for "rail to rail opamp".
     
    Last edited: Jul 28, 2011
  6. Jul 28, 2011 #5
    Hello,

    Thats great, thanks for that!!

    Seán
     
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