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TLV320AIC1110: Some questions

Ryu Yamashita
Expert 2640 points
Part Number: TLV320AIC1110

Tool/software:

Hi team,

(i)
Is 1.36 Vpp the maximum voltage level for EAR2?
Overload-signal level (3 dB): There is also a value of 1.925V,
I would like to know how I should consider this value.
(For example, if 0dBm is increased by 3dB with Receive PGA, etc., will the above voltage value be obtained?)

(ii)
If biased by MBIAS, it is calculated to be
2.65V + 1.36Vpp/2 ≈ 3.33V in the calculation.
When biased by MBIAS, is there any problem if the maximum Vo value of 3.6V is not exceeded?

(iii)
Can you please tell me about the internal reference voltage of MIC1P-1N?
Currently, the MIC1P-1N is powered on with MIC1 select,
The level is about 1.3V when MIC1 is powered on with MIC1 select and no voice data is being exchanged.

Best Regards,
Ryu.

  • 0
    TI__Mastermind 34370 points

    Hi Yamashita-san,

    i) The dBm0 is a bit of an antiquated unit, but 0dBm0 is a "digital milliwatt" and is a common reference signal in telephone networks. The reference value given in the datasheet is to compare to this reference value. However take note of Note 11 below the table that shows the RX PGA gain is -1dB here, so the resulting output is slightly below the typical milliwatt voltage of 0.775Vrms (assume 600ohm load). Comparing to modern digital signals (dBFS) a dBm0 signal saturates at ~3dB above the 0 dBm0 level, which is where the overload spec is derived. This article has a good explanation of the unit: https://en.wikipedia.org/wiki/DBm0

    ii) The MBIAS will not affect the input level, since the coupling caps will block the DC offset provided by MBIAS.

    iii) The internal reference voltage you are measuring is used to bias up the mic input signal so that there is no negative voltage on the input and so that the 0 point of the ADC is defined. This reference voltage is treated as the middle point of the ADC conversion, so the mic signal will oscillate around this reference voltage and the ADC will measure the oscillation. 

    Best regards,
    Jeff McPherson