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WEBENCH® Tools/TLV320AIC3256EVM-U: TLV320AIC3256EVM-U

Robert Rountree
Prodigy 70 points

Part Number: TLV320AIC3256EVM-U
Other Parts Discussed in Thread: TLV320AIC3120

Tool/software: WEBENCH® Design Tools

I am working on a TLV320AIC3256EVM-U module to determine if it will work for an audio system for hearing impaired people. I have applied a 1 KHz sine wave (100 mVp-p) to the line-in input and monitored the headphone output on my scope. Both analog bypass circuits work fine. My questions are:

1) If I use the ADC mini-dsp for signal processing, can I send the output directly to the DAC to produce an output signal?

2) If so, how do I do this? The documentation calls the ADC part the record path and the DAC the playback path.

3) I don't want to record anything. I just want to filter an input signal, adjust the gain at different frequencies, and produce an analog output signal. For example, the gain of the audio output at 1 KHz may be 20 db, but the gain at 10 KHz may be 80 db. Will the AIC256 produce a 60 db audio output signal gain difference from 1 KHz to 10 KHz? An equalizer may not provide this differential.

4) My initial thought was to use the 5 BiQuad filters with 5 different fc values to do this. Will this provide the gain difference?

5) What is the best TI product for doing this for a portable, battery-powered audio system?

6) Does TI do audio system designs such as the evaluation modules, or do have external design houses do the designs?

7) Can you recommend a design firm if TI does not do board designs? I would like to contact them. If TI does do such designs, can you send email contact information?

Thanks and best regards,

Bob Rountree

  • 0
    TI__Guru 57800 points

    Hi, Robert,

    Please refer to my answers below:

    1. Yes, the miniDSP of this device features a couple inter-processor blocks that can be used to stream the data from the miniDSP_A to the miniDSP_D so it can be played on the DAC. The miniDSP of this device is configured and programmed using PurePath Studio GDE (PPS).
    2. As mentioned, this can be done with the inter-processor block [DSP_A_DSP_D]. 
    3. I think this can be implemented in the miniDSP with the Biquad blocks available. 
    4. Probably the biquads should be able to provide the required signal conditioning, I recommend to check this in PPS. 
    5. We have a couple codecs with miniDSP available, any of them should be able to handle the required processing. Maybe you can take a look to our TLV320AIC3120, this is a device with miniDSP that is oriented to portable applications and has an integrated Headphone amplifier and Stereo Class-D speaker driver. 
    6. We usually design our EVMs, the gerber files should be in the product folder of our EVMs.
    7. Unfortunately, We don't have a preferred design house we can recommend.

    Hope this information is useful, please let us know if you have further questions.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0
    Prodigy 70 points
    Diego, thanks very much for your prompt response. I requested the PPS GDE software this morning. According to the response I received, I will receive download instructions in a few days if approved.  
     
    I looked at the AIC3120, but think the AIC3256 may be a better choice. A stereo CODEC is necessary, because hearing in left and right ears of hearing-impaired people may be very different.
     
    FYI, attached is a typical audiogram with right in red and left in blue. A normal hearing threshold is about 20 db through 10 KHz. A difference in left and right hearing levels may be much greater than in this audiogram.
     
    So the frequency-specific gain of each channel should be programmed separately. Will the mini-DSP allow me to program frequency-specific gain of the left and right channels independently?
     
    Also, a class D amp may not be necessary, since the circuit must be used with ear buds. Speakers would be very uncomfortable for anyone in the same room with the hearing impaired person. I think the AIC3256 will drive 16 ohm ear buds directly.
     
    Thanks again,
    Bob Rountree
     
  • 0 in reply to Robert Rountree
    TI__Guru 57800 points

    Hi, Robert,

    Thanks for the update, from your comments I agree in selecting the 'AIC3256 as the best option.

    Regarding your question, the miniDSP of this device is very flexible, so it is possible to perform the required filtering for each channel independently.

    Regards,

      -Diego Meléndez López
       Audio Applications Engineer