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TLV320ADC3101: SNR details

Yuli Starodubtsev
Prodigy 80 points
Part Number: TLV320ADC3101
Other Parts Discussed in Thread: PCM1862,

Hello,

I wonder about the difference in minimal (80dBA) and average (92dBA) on this part. That difference is much worse than, say, PCM1862 has. At the same time, the FFT from the datasheets show only about 10dB difference between these two ADCs. on average values, that's about right. On minimal values, it is not.

The TLV320ADC3101 has features that PCM1862 does not have, and I would love to use it, but 80dB would not be acceptable in my application.

My question is - what is the nature of that 80dB SNR? is it low-frequency flicker noise (that I could possibly filter out), or does the SNR depend on the date code or the factory?

Also, is there data on SNR within 100Hz - 10kHz range?

Thanks!

  • 0
    TI__Guru* 84915 points

    Hi, Yuli,

    The TLV320ADC3101 SNR measurements were made under the following test conditions:

    At 25°C, AVDD = 3.3 V, IOVDD = 1.8 V, DVDD = 1.8 V, fS = 48-kHz, 16-bit audio data, 0-dB PGA gain, IN1 inputs selected and AC-shorted to ground, A-weighted filter and 20KHz low-power output filter.

    Typically the SNR is 92dB with the conditions above. It may vary down to 80dB. However, this SNR value can be improved by modifying several ADC3101 functions, such the PLL coefficients and processing blocks. Additionally, a good layout design would ensure that the SNR level will be optimal. You may find some layout considerations in the wiki article below if you are interested:

    https://e2e.ti.com/support/data_converters/audio_converters/w/design_notes/3377.common-noise-issues-in-codecs


    These SNR values were measured A-weighted over a 20-Hz to 20-kHz bandwidth using an audio analyzer

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 80 points
    Hi Luis Fernando Rodríguez,

    I understand how the measurements were taken. The datasheet is straightforward on it, too. I'm sure also that the measurements were made with close to optimal layout. So, I do not expect SNR to be better than 92. But the "may vary down to 80db" is what bothers me. it actually means that I cannot rely on that ADC for my application.

    Still, I wonder what might be the reason for SNR to go that low (for a 24 bit device).

    thank you,
    Yuli