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DIR9001: PLL doesn't look work

Part Number: DIR9001

Hi team, 

PLL doesn't look work. Does this device require external crystal oscillator? My customer doesn't use FSOUT0 and FSOUT1 functions. so they don't use crystal. He seems when there is an SPDIF input, PLL works and generate clcoks without external crystal oscillator.

Could you please discover the cause?

Best regards,

Shunsuke Yamamoto

  • Hello, 

    Pin 28 (CKSEL ) is used for selection of system clock source, Low: PLL (VCO) clock, High: XTI clock. In PLL mode (CKSEL = L), output clocks (SCKO, BCKO, LRCKO) are generated from the PLL source clock.

    Pin 27 can be used as an indication of internal PLL or data parity error.

    As you see from this diagram, the I2S clks can be routed either from PLL or XTI and PLL doesn't need crystal to generte the clks.

    Please refer to 8.3.3.1 System Clock Source for detail "Description of PLL clock source"  and 8.3.4 PLL Clock Source (Built-In PLL and VCO) Description.

    Also please note that the built-in PLL requires an external loop filter, which is specified as below: (8.3.5 Required PLL Loop Filter Description):

    Regards,

    Arash