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TLV320DAC3203: High-resolution question

AJ Cheng
Genius 3615 points
Part Number: TLV320DAC3203
Other Parts Discussed in Thread: TLV320AIC3254

Hello.

We chose TLV320DAC3203 for high-resolution applications (24bit-96KHz sample rate, need good frequency response at 20~40Khz) but encountered some problems on EVM.

The EVM Line in input capacitor reference is recommended to be placed at 0.1uF, and the frequency response is very poor (-3dB points are more than 200HZ).

Changed to 1uF, the situation improved, but still not good enough, we hope that the target is at least -3dB point at 20HZ, currently added to 4.4uF, there is also 5dB attenuation at 20Hz.

Normally, the audio codec line in should have high impedance (the actual measured EVM input impedance is close to 70K ohm), Theoretically the input capacitor should not need to be added to such to high.

Please help suggest if there is a better way to Improve results.

In addition, the output capacitor EVM is 47uF, we increase it to 220uF, the BT I2S output low frequency response is not OK, and later adjusted to 440uF is closer to our demand,

but the 440uF MLCC capacitor is very large and very expensive (we can not consider Solid capacitor),

If need to put such a large capacitor, the price advantage of this codec no longer exists...

Is it necessary to replace the codec with cap free? Thanks for kindly help~

TLV320DAC3203 Frequency response.xlsx

  • 0
    TI__Guru* 84915 points
    Hello, AJ Cheng,

    Regarding your comments about the input capacitor, it is important to consider that the external AC-coupling capacitor and the input impedance create a 1st order high-pass filter. You would need to increase the capacitor value in order to approach the cutoff frequency to 0Hz and reduce the attenuation near of 20 Hz. This capacitor is required since it also helps to generate the common-mode voltage. You may also omit the capacitor but you would need to add the common-mode voltage in your input signal.

    The external capacitor is also required for the analog outputs, but as you mentioned you would need to increase its value. You may also try modifying the headphone resistor value (its default value is 25Kohms, but it can be also configured as 6k or 2k). The value modification will also modify the output frequency response.

    Please let me know if you have additional questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.
  • 0 in reply to Luis Fernando Rodriguez S.
    Genius 3615 points

    Dear Luis.

    Thanks for your reply.

    Is the TLV320DAC3203 suitable for use in (24bit-96KHz sample rate, need good frequency response at 20~40Khz) applications? RD also needs Analog input to do the mixing function.

    Space and price are important. Do not need output capacitors if possible. Do you have a recommended product? Thank you~

  • 0 in reply to AJ Cheng
    TI__Guru* 84915 points

    Hi, AJ,

    The TLV320DAC3203 supports frequency responses up to 192KHz. However, the frequency response may vary depending on the selected interpolation filter.

    Interpolation filters B and C can be used for this purpose. I'm including pictures of both frequency responses for details.

    The TLV320DAC3203 is our best device that fits all your requirements. You may also use an audio Codec such the TLV320AIC3254 that contains a programmable miniDSP. However, it also has an ADC section that probably you don't require in your design.

    Best regards,
    Luis Fernando Rodríguez S.