TLV320AIC3101: SNR of Line out (Differential)

Hello,

We'll have someone on our team take a look at this from our India team and get back to you

Best,

Carson 

Low Power Audio Applications

The SNR spec of 102db is assuming the full scale Input of  1.4vrms..  This corresponds to an input of 5.2dbU .With  zero data the idle noise is measured  and this can be used to get 

SNR=  Signal(dbU)-Noise(dbU).

Can you please explain the customer statement? I don't understand the text below very well .

Customer suppose that signal level of differential case is +6.02dB and noise level is +3.01dB. (from a case of the single ended perspective.) So full-scale is -0.8+6.02=+5.22dBu and noise is -97.8+3.01=-94.79dBu, then SNR is 100.01dB.

A question:

Is the 3.01db added to -97.8db to account for noise that comes when when the converter gets some data? 

You could also try changing the current setting as described below.

The TLV320AIC3101 allows trading off dynamic range with power consumption. The DAC dynamic range can be increased by writing to page 0, register 109, bits D7–D6. The lowest DAC current setting is the default, and the dynamic range is displayed in the datasheet table. Increasing the current can increase the DAC dynamic range by up to 1.5 dB.

Hello Sanjay,

Regarding +3.01dB, customer mentioned below comments.
- Differential noise voltage = SQRT( single-ended noise^2 + single-ended noise^2) = SQRT(2)*single-ended noise.
- 20LOG(SQRT(2)) = 3.01dB.

Customer will try your advice.

Best Regards,
Fujiwara

Hello Sanjay-san,

Would you please give your comments for above sentence of Differential noise voltage calculation? Would you please tell how to get 102dB SNR?

As I mentioned before, customer measured the noise level with no input data and it was -94.8dBu. So SNR is 5.2dBu-(-94.8dBu)=100dBu. That's why customer would like to know that SNR=102dB can be achieved or not, except register settings as you mentioned below.
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The TLV320AIC3101 allows trading off dynamic range with power consumption. The DAC dynamic range can be increased by writing to page 0, register 109, bits D7–D6. The lowest DAC current setting is the default, and the dynamic range is displayed in the datasheet table. Increasing the current can increase the DAC dynamic range by up to 1.5 dB.
----------------------------------

Best Regards,
Fujiwara

Hello Fujiwara -san,

Did the customer try the setting ? What performance did he get? 

Does he want to get 102db without using this setting?

Best Regards

Sanjay

Hello Sanjay-san,

Customer did not try the setting yet. Yes, customer would like to get 102dB without using this setting if 102dB is really reasonable value. Or if you can say that-94.8dBu noise level of differential configuration is reasonable (below customer comment is correct), customer will understand it.
----------------------------
Regarding +3.01dB, customer mentioned below comments.
- Differential noise voltage = SQRT( single-ended noise^2 + single-ended noise^2) = SQRT(2)*single-ended noise.
- 20LOG(SQRT(2)) = 3.01dB.
----------------------------

Best Regards,
Fujiwara