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Original question:

PCM1860 not seeing 24-bit resolution.

PCM1864: What DOUT waveform look like if not transmitting any data?

Ted Zhang
Intellectual 2280 points
Part Number: PCM1864


HI team,

In PCM1864 datasheet mentions "While the device is not transmitting data (but still being clocked), the DOUT pin will be Hi-Z (high impedance) to
allow other devices on the bus to transmit their data."  Is this for both master and slave mode? If configured in slave mode, does it mean if slave device not receiving any LRCK but still receive BCLK, Dout pin will be HI-Z?

My customer test on the PCM1864 and found when they're not recording, BCLK still there but no LRCK present, and they test the DOUT waveform as below picture shows with the same frequency as LRCK, is it correct? How to understand this waveform?

Thanks

  • 0
    TI__Intellectual 2280 points

    Some additional information in my customer's application, PCM1864 is configured in TDM slave mode, 16KHz LRCK, 16bit, BCLK 4.096MHz.

    Thanks for the help

  • 0 in reply to Ted Zhang
    TI__Mastermind 23050 points

    Hi Ted,

    If your device is configured in slave mode then you should be providing BCLK and LRCK. It is not a valid mode of operation otherwise and the DOUT line may not be Hi-Z since the device is not being clocked appropriately. This Hi-Z mode does apply to both master and slave operation and is intended to allow you to share the TDM bus with other devices and is a requirement to be able to do so. Most TDM devices support this functionality.

    Best,

    Zak