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TLV320AIC3204: Getting noisy signal with codec AIC3204 in audio project

AyatiLabs
Prodigy 10 points
Part Number: TLV320AIC3204
Other Parts Discussed in Thread: TMS320C5515

Hello,

I am using TMS320C5515 and codec AIC3204 for audio project.

Inside DSP C5515 i am generating 15 bit sine wave and then setting different codec gains (DAC and HP). 

Without load when i use negative gains of DAC below -6 i am getting highly distorted signal at codec output.

Below is my experimental results captured on Tektronik Digital Oscilloscope

The codec is set to run at 1.8V.

DAC Gain HP Gain Voltage P2P RMS Waveform Description
0 0 860mV 250mV Sinewave
-1 0 780mV 223mV Sinewave
-2 0 700mV 199mV Sinewave
-3 0 640mV 179mV Sinewave
-4 0 580mV 160mV Sinewave
-5 0 540mV 142mV Sinewave
-6 0 500mV 128mV Sinewave
-7 0 480mV 115mV Sinewave
-8 0 440mv 104mV Sinewave
-9 0 400mV 93.2mV Distorted Sinewave
-10 0 384mV 83.4mV Distorted Sinewave
-11 0 368mV 75.5mV Distorted Sinewave
-12 0 336mV 67.5mV Distorted Sinewave

Query: How can i achieve a clean sinewave of 100mv with THD < 1%. Can the currently selected codec AIC3204 and DSP 5515 satisfy the requirement. If yes what is the specific codec settings i must use to achieve it. The data sheet of codec mentions DAC gain range of -63 to 24. But i get highly distorted waveform at -6db itself.

Please help me resolve this issue.

Thanks,

Swamy

  • 0
    TI__Guru 64215 points

    Hello,

    Our primary support engineer for this product is out today.  Look for a response tomorrow or Monday.

    -Collin

  • 0
    TI__Expert 6995 points

    Swamy,


    On chapter 4 of this presentation there is an example of generating sine waves with C5505 with AIC3204. The C5505 is very similar to C5535. The example generates a twos complement 16-bit sine wave. 

    Distortion could be caused by too few digital samples of the sine wave, a DC offset on the sine wave, or improper setting of the AIC3204. Take a look at this example and see how it compares to your implementation. The AIC3204 and C5515 should be able to achieve your requirements.

    best regards,

      Pedro