Opamp input higher than supply

Discussion in 'General Electronics Chat' started by Sureshh, Jul 10, 2009.

  1. Sureshh

    Thread Starter New Member

    Jul 10, 2009
    2
    0
    Can we give input voltage higher than the supply voltage for the open loop Opamp? ex:LMV321
     
  2. millwood

    Guest

    you will have to look at the datasheet. the answer is typically yes, but very limited. usually you can get input slightly above Vdd by usually 0.3v.

    but check the datasheet to be sure.
     
  3. Sureshh

    Thread Starter New Member

    Jul 10, 2009
    2
    0
    thank you millwood for your response..

    Actually I wanted to know if we can give 20V input to the opamp with 3.3V supply...
     
  4. millwood

    Guest

    the answer is highly likely a "no", but check the datasheet for sure.
     
  5. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    You may consider using a resistor divider to get the voltage into the range where the opamp can handle it.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The LMV321's input maximum limits are the voltage rails, in your case ground to 3.3v.

    As StayAtHome mentioned, you can use a resistive divider to get the voltage within limits.

    If you want open-loop gain, look at comparators instead of opamps.
     
  7. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    Why do you want to do this? The input to the inverting pin is often thru a resistor and fom many circuits the voltage of the inverting pin hardly changes from 0. Just because you are using voltages of 20 volts does not mean the op amp has to see them.
     
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