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  • TI Thinks Resolved

OPA4187: Different grounds for power supply and inputs

Prodigy 70 points

Replies: 11

Views: 308

Part Number: OPA4187

Hi,

is it possible to use the different grounds for power supply and input of Op-Amp?  Please find the picture of the same.

  • And what could be the effects if we use like this?
  • In reply to Jai Kumar Reddy:

    Hi Jai,

    can you post the picture again?

    Kai
  • In reply to kai klaas69:

  • In reply to Jai Kumar Reddy:

    Hi Jai,

    a total isolation between the two grounds will not work, because the input bias current of OPAmp flowing out of the VIN pin must find a current path back to GND2.

    Kai
  • In reply to kai klaas69:

    Hi Kai,
    Basically we need to have isolation between input and output. The
    Can you please suggest how we can achieve analog signal isolation
  • In reply to Jai Kumar Reddy:

    Hi Jai,

    you could take one of TI's isolation amplifiers:

    www.ti.com/.../products.html

    How much isolation do you need? Can you tell more about your apllication?

    Kai
  • In reply to kai klaas69:

    Hi Kai,
    We have unisolated voltage to OpAMP input and output of apamp is connected to micro controller( which needs to be isolated) and power supply of op amp is isolated one.
  • In reply to Jai Kumar Reddy:

    Hi Jai,

    why do you need isolation? Is there a dangerous high voltage between the two grounds?

    Kai
  • In reply to kai klaas69:

    Hi Kai,
    We have mainly two sections. One is isolated section and other non-isolated section. Power Isolation is required for ODVA certification and so we are providing.
    But whatever the opamp section is there, at that place the input is coming from non isolated section and output should be applied to isolated section.
    So, please suggest.
  • In reply to Jai Kumar Reddy:

    Hello Jai,

    Isolation amplifier products are handled on another TI E2E forum so they can best assist you with any circuit details. When I search the TI we site here are some resources I found useful:

    You may need to condition the input signal before it proceeds to the isolation amplifier. If that is the case we can assist with recommending precision op amps.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

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