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TAS5753MD: MCLK Connection

matt holland
Intellectual 260 points
Part Number: TAS5753MD

The data sheet says "I2C Serial Control Interface Operational Without MCLK".

1) What is the benefit of using an MCLK (or disadvantage of not using one). 

2) If an MCLK is not used, can the pin simply be left disconnected?

  • 0
    TI__Mastermind 24835 points
    Hi matt,
    For some cases, SCLK can be used for MCLK input then user don't need to apply a special MCLK clock to the device. So MCLK pin can't be left disconnected.
    For most TASS57xx devices, 44.1/48-kHz mode allows the use of a 64*Fs MCLK rate. This rate also happens to be one of the supported SCLK rates. In system's where only one clock may be available, a common MCLK=SCLK=64*Fs rate is an option to overcome the limitation. -- This is valid only if the Fs rate is 44.1/48-kHz.
    Please find more info about the I2S clock requirement in this post in the Wiki. e2e.ti.com/.../2425.i2s-clock-requirements-on-tas570x1x2x3x-device-s
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Intellectual 260 points
    So in summary:
    -The only situation in which a separate MCLK is not required is if an allowed MCLK frequency lines up with an allowed SCLK frequency. For 48kHz this happens only when SCLK = 64*Fs (3.072MHz). In this corner case, would the SCLK source also be connected to the MCLK pin? or would the MCLK pin be left disconnected.

    -MCLK connection is actually required in all other cases besides the above described corner case.

    Is that correct?

    Do you have any app notes/wiki link to recommend for designing in an MCLK source for the case where the I2S source can not provide one?
  • 0 in reply to matt holland
    TI__Mastermind 24835 points

    Hi Matt,

    Your understanding is correct. But for these corner cases, you still need to apply the SCLK signal to MCLK pin externally. Unfortunately there is no application note for this usage. 

    Best regards,

    Shawn Zheng