TLV320AIC3204: Large noise for output

Hi Peter, 

The Apps engineer who supports codecs is out of office, so I apologize if the quality of support is poor. 

From this old thread, the issue may be related to out of band noise appearing in the audible spectrum, https://e2e.ti.com/support/audio-group/audio/f/audio-forum/730315/tlv320aic3204-tlv320aic3204-headset-dac-output-with-pop-noise-and-white-noise

Regards,

Arthur

Dear Arthur,

Thanks for your reply!

If there is any other comments, please help to update.

Arthur will be out of office so I have re-assigned to Sanjay.

Is the input data provided over I2S? Is do what are the timIngs

Is a headphone connected? Can you please remove the headphone and see if there is any improvement on the pin waveform?

Can you also look at the waveform on LOL and LOR ?

Hi Sir,

Feedback is below.

1. I2S: 16bit 8kHz sampling rate

2. CODEC pin 25 HPR open, disconnect headphone and the noise is the same. no output for LOL and LOR.

3. change the output from LOL or LOR and disconnect headphone, no output from HPL/HPR, the noise seems a little smaller than before.

Test with different PCM gain settings:

PCM level of the top is 9% of 16bits, if set codec gain to same as bottom PCM level, the noise is huge.

PCM level of the bottom is 70% of 16bits.

Questions are:

1. what is the proper signal attitude for the codec?

2. what is the proper gain setting for the codec?

3. is there any sample code for the codec?

Thanks.

Hi Peter,

An oscilloscope is not the best instrument to measure noise. Depending on the setup and bandwidth the noise might look worse than expected, as you might be seeing noise outside of the audio band. Can you measure the performance using an instrument such as Audio Precision? A THD+N measurement and FFT would be very useful to understand if this is an issue. 

Brian