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NE5532: Review circuit

Inho Jeon
Expert 1452 points
Part Number: NE5532


Audio_circiut.pdf

Dear Ti and all,

I designed circuit of audio device. That is MIC station : Input MIC and AUX with chime bell and control another audio devices.

Above this, I attached a part of audio circuit. That is 2 MIC inputs ; Condenser MIC & Dynamic MIC. that inputs are mixed.

Output is selected mode 2 ; Mixed MIC or Chime bell. 

Please, Review that circuits.

 

And, because I do not designed below this red circle circuits, so I wondering that circuits.

I think it is improved for ESD & EMC but I don't know about that. 

Please, inform me that my question ; whether need to another part for improve that circuit.

Best Regrads,

Inho Jeon

  • 0
    TI__Guru* 84915 points

    Hi, Inho,

    Yes, all the circuitry that you mentioned is used to reduce noise on the microphone inputs. Basically, these are filters that reduce ripple on the microphones lines.I don't think additional circuitry is required for audio improvement.

    I also reviewed the rest of the microphone connections and everything looks fine.

    Please let me know if you have additional questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Expert 1452 points

    Dear Luis,

    Thank you for reply.

    I have a question.

    On my circuits attached file, Q20,Q21, RLY1 is connected digital GND(that is for digital device & power ground. NOT *AGND).
    *AGND is for audio ground

    Those parts are operated for AUDIO MUTE.

    Is that right connection?

    Please, Inform me right way for my question.


    Best Regards,

    Inho Jeon

  • 0 in reply to Inho Jeon
    TI__Guru* 84915 points

    Hi, Inho,

    It depends of the digital activity on your design. Usually, we recommend to separate the digital activity from the analog activity since there could be some high-frequency noise content on the digital portion. There are some devices whose digital portion works at a high frequency due to internal modulation or oscillators. If you design has this kind of activity, there could be risk to have high-frequency noise (usually out-of-band noise) at the output. If this is the case, I would recommend to route Q20, Q21 RLY1 to analog ground.

    Best regards,
    Luis Fernando Rodríguez S.