This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLV320DAC3100: DAC3100 line out pop noise

Part Number: TLV320DAC3100
Other Parts Discussed in Thread: TLV320DAC3203

Hello Audio Folks, I have a customer using DAC3100 for both headphone and line out. They get pop noise issue on the line out. For headphone, the pop noise is small and acceptable. But, for line out, the pop noise is big.

They are using 47uF blocking cap. The headphone and lineout are the same connector. So, the only difference for headphone and lineout will be the load impedance.

I have studied the pop noise and guess the problem is the lineout impedance is too big. I have checked TLV320DAC3203 Application Reference Guide. The pop free design is using Rpop inside the IC as in figure 2-3 in page 17 in the Ref Guide. The issue is that DAC3203 has a register (page 1 reg 20) to select the Rpop value. But, this register is reserved in DAC3100. Anyway, I have tried to set it but it has no effect and always read back as zero.

Below is the IC headphone pin waveform using Rload = 1K ohm. The pop happens on the beginning of the bias ramping. I have set the headphone power on time to 1.2 sec so that it is a way behind the completion on the bias ramping up. If using Rload = 10K, the intial voltage change will be even bigger.

Channel 1 (blue) = IC output pin. Channel 3 (magenta) = headphone/lineout connector.

I have also tried to change to  lineout driver with page 1 register 44 bit D2&D1. But, if doing so, there will be no ramping on the IC output pin. It will immediately go to the target bias voltage like a step.

So, is there any advice on the problem? Is there any hidden register to change the Rpop value?

 

Regards,

Kes