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TLV320AIC3204: MCLK to audio interface host resistor or cap

Gene Qiu
Intellectual 1720 points
Part Number: TLV320AIC3204


Hi team,

As i noticed on datasheet, the layout example is to 'help prevent overshoot and reduce coupling, place near the source 10ohm for MCLK' 

While customer used aic3204for many years with a 1nF cap to MCLK, works fine. But recently, they adjust the VCO frequency smaller, sometimes in some prototypes there is no DAC output while I2C is normal. But place the scope on the cap, the DAC output normal.

After changed the 1nF to 0hm, DAC output and works fine. So i am wondering is there difference or consideration about MCLK with resistor or cap, which would cause this phenomenon.

Best Regards,

Gene

  • 0
    TI__Guru 64045 points

    Hello Gene,

    The recommended solution to reduce ringing and reflections is to place a 10-33Ohm resistor in series with the signal lines, close to the driver side of the line.

    A 1nF capacitor is really large to place directly on a ~6-24MHz signal line and the resulting MCLK driver will burn a lot of power and the resulting signal is likely very triangular versus a good square wave.  When you probe the MCLK line, what does it look like?  Marginal timing issues caused by the waveform disturbance may work on some products, and not others which could explain this behavior.