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ADA4075-2 and SSM2167 Q's

Hi,

We are looking at using the ADA4075-2 instead of the OP275, as recommended by ADI, as a balanced line driver to the AD1974. However, the reference design uses trimpots whereas these are not shown for the OP275 reference design. As we are looking to have 12-16 inputs per PCB, it isn't feasible to tune each individual trimpot. Can these be left out or are there standard resistor values which are used which produce 'good enough' results.

Further to this, there are in some places specifications for the ADA4075-2 and SSM2167 in the datasheets as to what type of capacitors to use, however not always. I was wondering for a general idea of what types of capacitors are suitable for these devices. I have read conflicting information about how 'bad' ceramic capacitors are in audio etc and just want to get some device specific info.

Thanks

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  • Hi,

    I will be happy to help you with your questions. Can you please tell me which reference design you are consulting, that has trimpots? In order to help you, I would like some other information about your system. What power supply rails do you have available? What is your maximum signal level entering this circuit (RMS or p-p)? I will be specifying the circuit with a 100 kHz low pass filter. The use of 1% resistors and 10% capacitors will yield the performance specs shown in the datasheet.

    As far as capacitors are concerned: I would recommend high quality NP0 ceramics for small value filter capacitors, X7R ceramics for local power supply decoupling and high temperature electrolytics for AC coupling in the audio path. Metal film capacitors are superior for audio, but I would only recommend them in a through-hole package; I do not have good experience with this type of capacitor in a surface mount package. They do not seem to survive assembly.

    I look forward to hearing more about your design

    Regards,

    Coleman

Reply
  • Hi,

    I will be happy to help you with your questions. Can you please tell me which reference design you are consulting, that has trimpots? In order to help you, I would like some other information about your system. What power supply rails do you have available? What is your maximum signal level entering this circuit (RMS or p-p)? I will be specifying the circuit with a 100 kHz low pass filter. The use of 1% resistors and 10% capacitors will yield the performance specs shown in the datasheet.

    As far as capacitors are concerned: I would recommend high quality NP0 ceramics for small value filter capacitors, X7R ceramics for local power supply decoupling and high temperature electrolytics for AC coupling in the audio path. Metal film capacitors are superior for audio, but I would only recommend them in a through-hole package; I do not have good experience with this type of capacitor in a surface mount package. They do not seem to survive assembly.

    I look forward to hearing more about your design

    Regards,

    Coleman

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