How to unleash the outputs of operational amplifiers are connected to a common load?

Used operational amplifiers AD8534 and AD8532.

  • 0
    •  Analog Employees 
    on May 13, 2015 8:00 PM

    Hi Vladimir,

    What do you really want to accomplish?

    It will be helpful if you could share your circuit or perhaps your end application.

    Regards,

    Phil

  • Hi, Phil. In the figure, part of the circuit. Maybe there is nothing wrong with the signals from the outputs of the operational amplifiers can not simultaneously appear at the output due to a temporary demarcation work DACs. But I am concerned about their influence in the static mode. In the static mode, the output voltage is equal to 5V. The main thing for me - the absence of a possible short circuit. When designing a circuit I made a mistake and did not notice that connect the output of the operational amplifiers is now trying to address this shortcoming.

  • 0
    •  Analog Employees 
    on May 18, 2015 9:42 PM

    Hi Vladimir,

    I just want verify your question. You want to disconnect the output of one of the op amp once it is not active? I'm seeing you have AD8534 for one of the DAC and AD8532 for the other DAC where these op amp outputs are connected to one load. If that is the case, I want to recommend a mux to control the output of your op amp by selecting one op amp at a time. You can check our Multiplexers here:http://www.analog.com/en/products/switches-multiplexers.html You should consider your bandwidth, voltage range requirements as well as the number of channels you needed. I also want to introduce family of op amps with disable functionality. This will eliminate the use of  mux to select the op amp you want active and not. This article (Amplifier Disable Function Eliminates Need for Multiplexers in Multichannel Applications ) will be a nice read to start with. You can start with these amplifiers with disable function: ADA4895-1, ADA4897-1 or AD8041.

    Please let us know if it answers your concern or you have any follow up questions.

    Regards,

    Phil

  • Hi, Phil. Disable one of the outputs is very convenient, but in the current development of MUXs difficult to use due to the fact that the board is already divorced and assembled. Mux is useful when there are a lot of free pins I / O of uC, and when there is no continuous signals. I look for a version with minimal modifications of the PCB.

    Is it possible to isolate the outputs of operational amplifiers conventional diodes, the more that the output can only be positive?

    In developing the new scheme may take note of your valuable comments and suggestions.

  • 0
    •  Analog Employees 
    on May 25, 2015 5:08 PM

    Hi Vladimir,

    I can't recommend to use conventional diodes in this application.You can't achieve best performance of your circuit in this condition.

    Since you are already modifying your board, I suggest you use op amp with disable functionality as what I recommend earlier on this thread.

    Apologies on late response.

    Regards,

    Phil