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PCM3060: About BCK1/2 high/low time

Tao_2199
Genius 5770 points
Part Number: PCM3060

Hello,

Regarding to BCK1/2 high/low time on PCM3060,my customer is asking a question.

 

(Question)

According to datasheet Figure24, BCK1/2 high/low time is described as following.

 

Why do these times have range from 40% to 60%? Why isn’t these fixed to 50%?

They think BCK is divided by SCKI. At that time, BCK and SCKI are even ratios of integers.

So, the duty ratio should be fixed to 50%.

Could you please tell us why these times have range from 40% to 60%?

 

(My customer configuration)

・LRCK=1fs

・BCK=64fs

・SCKI=512fs

(BCK= 1/8 * SCKI)

*In above case, will the duty ratio be fixed to 50%?

 

Regards,

Tao_2199

  • 0
    TI__Mastermind 23050 points

    Hi Tao,

    The spec just shows that the device can tolerate some deviation in the duty cycle of BCLK, which most likely means the falling edge of BCLK is not used. I'm not sure why they are thinking BCK would be divided by SCKI? If they are operating in slave mode, all clocks are inputs. It is still important that the period of BCK is a valid integer multiple/ratio of LRCK and SCKI.

    Best,

    Zak

  • 0 in reply to Zak Kaye
    Genius 5770 points

    Hello Zak,

     

    Thank you reply.

     

    They will use master mode.

    According to datasheet page15, master mode, is described as following.

    “In master mode, BCK1/2 and LRCK1/2 are outputs from the PCM3060. BCK1/2 and LRCK1/2 are generated by

    the PCM3060 from SCKI1/2, and BCK1/2 is fixed at 64 fS. DIN is sampled on the rising edge of BCK2, and

    DOUT is changed on the falling edge of BCK1. The detailed timing specification is shown in Figure 25.”

     

    (1) In this case, duty cycle of BCLK has some deviation (±10%) in device.

    My understanding is correct?

    (2) Will this deviation in master mode affect the BCK of Audio Decoder/Encoder?

     


     

    (3) Where does the cause of this deviation come from the device?

     

     

    Regards,

    Tao_2199

  • 0 in reply to Tao_2199
    TI__Guru 63985 points

    Hi Tao,

    Looks like we missed your follow-up response.  There was a related question that just came in that should be helpful:

    https://e2e.ti.com/support/audio/f/6/p/966377/3571167#3571167