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TLV320AIC3204 / Gain by Differential input

Ryuji
Guru 20090 points

Other Parts Discussed in Thread: TLV320AIC3204

Hello,
 
Our customer sets all of gain in the TLV320AIC3204 to 0dB by differential input.
According to attached image from TLV320AIC3204 refference guide , minnimum Gain will be 6dB when Differential input and Rin=10kΩ.
However, gain will not be 6dB in our customer. Gain will be 0dB.
 
Can  we  use by 6dB at the differential input and 0dB gain settings ?
If yes, are there any possibility of this issue ?
 
 
Best Regards,
Ryuji Asaka
  • 0
    TI__Guru**** 189401 points

    Hi, Asaka-san,

    We will look at this early this week and get back to you. Sorry for the delay.

    -d2

  • 0
    TI__Mastermind 46195 points

    Hello Ryuji-san,

    The input circuit of the AIC3204 is a fully differential amplifier. This circuit has a programmable input resistor (Rin) and a programmable pre-amplifier (MicPGA).

    Setting Rin = 10k, MicPGA = 0dB and a 500mVrms differential sine wave (250mVrms per pin)  will result in full-scale (in other words, 0dBFS). If you want to do 1Vrms differential (500mVrms per pin), then you must change Rin to 20k and set MicPGA = 0dB.

    Regards,

    J-

  • 0 in reply to J-
    Guru 20090 points
    Hello Arbona san,
     
    Are below my understanding correct ?
     
    ------------------
    <MicPGA=0dB, Rin=10kΩ, Differential Input>
    In2_L=250mVrms
    In2_R=250mVrms
    Vin diff=500mVrms
     
    HP_L=250mVrms
    HP_R=250mVrms
    Vout_diff=500mVrms
     
    <MicPGA=0dB, Rin=20kΩ, Differential Input>
    In2_L=250mVrms
    In2_R=250mVrms
    Vin diff=500mVrms
     
    HP_L=500mVrms
    HP_R=500mVrms
    Vout_diff=1,000mVrms
    ------------------
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Mastermind 46195 points
    Ryuji-san,
     
    The ADC full scale is 1Vrms. So 500mVrms per leg and 0dB MIcPGA Gain and 20k Rin results in 1Vrms = 0dBFS.
     
    <MicPGA=0dB, Rin=10kΩ, Differential Input>
    In2_L=250mVrms
    In2_R=250mVrms
    Vin diff=500mVrms 1000mVrms (0dBFS) Because IN2L - IN2R = 2*IN, and 20k/10k = 2, hence 4*IN.
     
    HP_L=250mVrms 500mVrms (0dBFS corresponds to 500mVrms)
    HP_R=250mVrms 500mVrms (0dBFS corresponds to 500mVrms)
    Vout_diff=500mVrms 1,000mVrms
     
    <MicPGA=0dB, Rin=20kΩ, Differential Input>
    In2_L=250mVrms
    In2_R=250mVrms
    Vin diff=500mVrms (-6dBFS) - Because IN2L - IN2R = 2*IN
     
    HP_L=500mVrms 250mVrms (-6dBFS corresponds to 500/2 mVrms)
    HP_R=500mVrms 250mVrms (-6dBFS corresponds to 500/2 mVrms)
    Vout_diff=1,000mVrms 500mVrms
     
    Regards,
    J-