PCM1781: phase difference between VOUTL and VOUTR.

Yuta Nishie

Part Number: PCM1781

Hi,

The customer is using a PCM1781 and says that there is a phase difference of about 46us (about 2Fs since the digital sampling frequency of the input is 48 KHz) between the VOUTL and VOUTR.
Is this 2Fs within the normal operating range?

The customer specification requirements are as follows:
・1KHz sine wave is input digitally
・Lch and Rch input data are identical
・SCK=24.576 MHz, BCK=3.072 MHz, LRCK=48KHz
・DEMP0=0(Low), DEMP1=0(Low)

Best Regards,

Nishie

over 2 years ago

Arash Loloee over 2 years ago

TI__Mastermind 31751 points

Hi Nishie,

The phase difference is not a parameter mentioned in the datasheet ( only group delay is there) but 46us sounds too much.

Is it changing accordingly with different Fs? or it is a fixed 46us all the time?

Can you flip the data to the channels and see the phase shift follows.

It sounds to me like a DSP issue sending the data not the DAC itself. So can you verify the data is coming to the DAC according to what you expect?

Regards,

Arash

Yuta Nishie over 2 years ago in reply to Arash Loloee

Genius 5220 points

Hi Arash-san,

Thank you for your support.

I will check with the customer regarding your question.

Best Regards,

Nishie

Yuta Nishie over 2 years ago in reply to Yuta Nishie

Genius 5220 points

Hi Arash-san,

Sorry for the late reply.
This matter has been resolved.
Thank you for your support.

The cause was that the constant of the peripheral circuit was wrong.

Best Regards,

Nishie

Arash Loloee over 2 years ago in reply to Yuta Nishie

TI__Mastermind 31751 points

Thanks for letting me know.

Regards,

Arash

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PCM1781: phase difference between VOUTL and VOUTR.