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Op-amp buffer

Discussion in 'General Electronics Discussion' started by Akshatha Venkatesh, Nov 30, 2017.

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  1. Akshatha Venkatesh

    Akshatha Venkatesh

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    Jan 14, 2017
    The below circuit is a current measurement circuit , the mosfet is always on in my application and the volatge across the shunt 100k is measured and given to ADC pin of uC.cananyone explain the function of the Opamp as voltage follower in the circuit ? What would happen if the opamp wasn't present ? The current at IDE- is 45V/45Mohm= 10 micro amp.[​IMG]
     
  2. Audioguru

    Audioguru

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    Sep 24, 2016
    The opamp has a high impedance input so that it does not overload the filtered input signal and it has a powerful output that can drive a low impedance output circuit that is not shown.

    How can the opamp drive a circuit not shown that has 45V? Maybe the output of the opamp clamps the 45V to its maximum lower voltage output?
     
  3. Akshatha Venkatesh

    Akshatha Venkatesh

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    Jan 14, 2017
    Sorry , I don't understand . I've mentioned the 45V only to give an idea of the current being measured.
     
  4. Audioguru

    Audioguru

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    Sep 24, 2016
    The load for the opamp is not shown so we do not know why the opamp is needed. The input of the opamp has a high impedance lowpass filter and the output of the opamp has a lower impedance lowpass filter that feeds the unknown load.
     
  5. WHONOES

    WHONOES

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    May 20, 2017
    Can you show the rest of the circuit including the input load and whatever the opamp is driving?
     
    Akshatha Venkatesh likes this.
  6. Akshatha Venkatesh

    Akshatha Venkatesh

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    Jan 14, 2017
    the load for the opamp is the microcontroller ADC pin.
     
  7. Akshatha Venkatesh

    Akshatha Venkatesh

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    0
    Jan 14, 2017
    the input load is a sensor probe element (PTC), the opamp is driving the microcontroller ADC input.
     
  8. Akshatha Venkatesh

    Akshatha Venkatesh

    145
    0
    Jan 14, 2017
    Hi, could you help me on this
     
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