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LM49352: I2S burst mode support

Jeffrey Chung1
Genius 3350 points
Part Number: LM49352


Hi,

I'd like to ask you about I2S burst mode support of LM49352. There is a noise issue on the blue box case(CP2615 to LM49352) of attached file, but there is no issue on the opposite direction application. The important thing is...I think that LM49532 can be supported the I2S burst mode or not. If support, please let me know how to fix it. Please refer to the attached file below.

I2S interface issue of LM49532.pdf

Regards,

  • 0
    TI__Guru 64205 points

    Hello,

    The LM49352 is not designed to operate with a "burst-mode" I2S - note that this operation is not part of the official I2S specification.

    That said, when in slave mode operation, many of the converters can clock out data properly with a burst BCLK, provided the individual bit timings shown in the datasheet are met.  The largest concerns will be making sure the WCLK is exactly the desired sampling rate, and then trying to match the previous BCLK frequency as best a possible without violating any of the bit timings and making sure you don't miss data.  

    Based on the waveform it's recommended to move the initial BCLK pulses closer to the rising/falling edges of your WCLK.

    Here are some tips:

    1. The actual sample rate will be determined by MCLK and the register settings 

    2. WCLK and BCLK are used to clock data out of the ADC.

    3. The data is not buffered and must be dealt with real time.

    4. WCLK must be at exactly the sample rate.

    5. In slave mode, BCLK may work in burst operation as long as it is fast enough to get the bits and doesn't exceed the max rate shown in the timing diagrams

  • 0 in reply to Collin Wells
    Genius 3350 points

    Hi Collin,

    Thanks for your support. It will help me understand the I2S operation of this chip. Let me ask you more question if I have some additional issues.

    Regards,

  • 0
    Genius 3945 points

    What is "I2S burst mode?" I've never heard of such a thing.

  • 0 in reply to Andy Peters
    TI__Guru 64205 points

    Hello,

    There is no "burst mode" part of the official I2S spec as mentioned in the first post.  I've heard customers refer to "Burst-mode I2S" when a customer is trying to use a standard SPI peripheral in their MCU to perform the audio serial interface communications typically handled by a McASP peripheral.  It will work on some devices if the guidelines/tips mentioned above are followed. 

    I'm not 100% connected to everything going on Audio related out there so i could be missing something another vendor is doing.