TLV320AIC3106: MAX/MIN Analog input voltage

AClemotte

Hi,

We're designing a PCB and we plan to place a TLV320AIC3106. The spec about MAX/MIN Analog input voltage is (source SLAS509F –DECEMBER 2006–REVISED DECEMBER 2014):

Analog input voltage

to AVSS_ADC

–0.3 | AVDD + 0.3

So, the analog signal cannot be less than 0.3V, so this signal must have a bias.
However, on the evaluation board the signal is decoupled with a 100n capacitor.

- Should the line input signal have a bias voltage?
- If yes, why do the specifications speak of a minimum analog input voltage of 0.3V?

over 6 years ago

0 Collin Wells over 6 years ago

TI__Guru 64355 points

Hello,

Good question. The TLV320AIC3106 has an internal bias voltage of 1.3V that pulls-up the AC coupled input voltage to a roughly mid-supply voltage level. The input signal range is up to 0.707Vrms or 1Vpp which rides on the 1.3V DC bias so internally the signals swing 0.3V to 2.3V into the ADC.

0 Collin Wells over 6 years ago in reply to Collin Wells

TI__Guru 64355 points

Perhaps to add a little more detail:

Should you DC couple the inputs then you shouldn't apply voltages outside of the -0.3V to AVDD+0.3V range.

Should you apply AC voltages, then don't apply signals so large that while riding on the internal 1.3V DC bias they'll violate the same abs max ranges of -0.3V to AVDD+0.3V.

0 Aaron Estrada over 6 years ago in reply to Collin Wells

TI__Mastermind 22950 points

Hi Collin,

Thanks for the detailed response!

I do want to note that in the first response, the max input is actually 2Vpp and not 1Vpp.

Regards,

Aaron

0 AClemotte over 6 years ago in reply to Aaron Estrada

Expert 1060 points

Yes Aaron Estrada, this is true, thanks.

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TLV320AIC3106: MAX/MIN Analog input voltage