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TLV320AIC3109-Q1: Supported Audio Data Bit Depth

Gabriel Lin
Prodigy 20 points
Part Number: TLV320AIC3109-Q1


Hi,

I'm working with TLV320AIC3109-Q1 on our custom board and we would like to transmit the audio data in I2S mode. As we learned from the spec, it seems that the max bit depth supported is 16-bit. Then we assume that when the data work length is set to 20/24/32 bits, only MSB to MSB - 15 bit are filled with valid data and the others are padded with 0. However, based on our measurement, when we set the data work length to 24-bit or 32-bit and run the analog to digital recording with a 32-bit slot width I2S protocol, there are 24-bit or 32-bit valid data(assuming that non-zero constantly changing data are valid) instead of 16-bit. Would like to ask if our understanding is correct.

If it is needed, I will upload the oscilloscope measurement screenshots.

Thanks,
Gabriel

  • 0
    TI__Mastermind 29765 points

    Hi,

    This device supports bit depth of 16/20/24/32 as mentioned in section 7.3.2. I'm not clear of your statement of "the max bit depth is 16-bit" and "when we set the data work length to 24-bit or 32-bit and run the analog to digital recording with a 32-bit slot width I2S protocol, there are 24-bit or 32-bit valid data(assuming that non-zero constantly changing data are valid) instead of 16-bit". If you set the bit depth to 24 it's correct to see 24 bit data, why do you expect to be 16 bit?

    Is the codec master or slave mode? 

    Regards.

  • 0 in reply to pdjuandi
    Prodigy 20 points

    Hi Pdjuandi,

    We have this question because we read that the dynamic range of ADC is 93dB and the value of DAC of differential line out is 97dB. Both values are close to the min of the 16-bit format data so we think the codec is only able to deal with 16-bit data. Is our understanding correct?

    pdjuandi said:
    Is the codec master or slave mode? 

    The codec is running in clock slave mode.

    Thanks,

    Gabriel

  • 0 in reply to Gabriel Lin
    TI__Mastermind 27710 points

    Hi,

    Out TI experts are out office today for US holiday so please be patient as responses are delayed.

  • 0 in reply to Gabriel Lin
    TI__Mastermind 29765 points

    Hi,

    Yes, this device ENOB is around 15 bit so you will see around that number of bits.

    Regards,

  • 0 in reply to pdjuandi
    Prodigy 50 points

    Hi

    The waveform below is measured when 1KHz 2Vpp is applied to MIC1P, and 32-Bit word length is set.

    I want to know, if the ENOB of AIC3109-Q1 is 15-Bit, why there is 32-Bit valid data? It should be 16-Bit, is my understanding correct?

    BCLK: 3.072MHz (Slave mode)

    WCLK: 48KHz

     

    Sam

  • 0 in reply to Sam Chang1
    TI__Intellectual 2620 points

    Hi Sam,

    Peter is out of office for a few weeks, so I will reply. ENOB of 15 bits is based on the analog performance of the device and it is the limit of the resolution when going through a conversion. However for internal processing there is a benefit to having more bits to avoid rounding errors for digital filtering and processing. So the math is done with 32 bits precision and all those bits are presented at the digital output to get maximum precision. In practical terms, most of the LSBs can be ignored at the output. You can just use the first 16 bits. You can measure your system to see if there is any benefit from utilizing the remaining bits, but usually there is not a lot of benefit.

    Brian