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OPA145: OPA145

Rituraj Mukherjee
Prodigy 20 points
Part Number: OPA145

Hello,

I would like to have voltage subtractor without using OPAMP. In the circuit attached below the voltage difference across A and B is 21V with point A=15V and  point B=-6V. I want to develop a circuit that will have a voltage of 21V when referred to AGND(ground). How can I do this from the existing circuit WITHOUT ANY OTHER OPAMP. Please help me with this issue.

Best Regards,

Rituraj

  • 0
    TI__Guru 63050 points

    Rituraj,

    There are many ways to generate the output of 21V, however, no op amp allows Vout  to go above its positive supply (Vout<Vcc) - for this reason circuit in Fig 2 does not work.

    It is not clear to me what the input voltage limitations are but the simplest way to generate 21V would be to use a minimum of 22V supply as shown in Fig 3.

    Rituraj OPA145.TSC