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Original question:

WL1831MOD: [WL1831][HFP][iphone8 ios11.2.2]The income call ringtones are different, the first time ringtone volume is too...

WL1831MOD: audio I2S /PCM output power

Amelie Zheng
Genius 10865 points

Part Number: WL1831MOD
Other Parts Discussed in Thread: WL1831

Hi Team,

May I ask what is the I2S/PCM output power of WL1831? How much is the dBm or dBfs?

  • 0
    TI__Mastermind 23525 points

    I'm not sure I understand what you are asking for.  Power output in dBm for a digital signal?  Can you please elaborate?

    Thanks,

    Travis

  • 0 in reply to tscheck
    TI__Genius 10865 points

    Hi Tscheck,

    As it is I2S/PCM, the data bit is 16 bit(unsigned).

    The sample of digital audio is 16-bit unsigned, and the maximum value of 16-bit unsigned is 65536. Therefore, I think the calculation formula of dBFS is as follows:

    So does it mean the dBFS of WL1831 PCM is -96dBFS? Is it correct?

    And may I also ask the dBm? Is it just related to Power Amp which use PCM as input? So the value of dBm depends on PA?

    Thanks!

  • 0 in reply to Amelie Zheng
    TI__Mastermind 27145 points

    Hi,

    I2S Bus is a digital interface ( like SPI / I2C) to connect Digital audio signals from one chip to the other chip.

    dBFS unit is not meant for Digital bus signals. Digital bus signals goes from High ( > 0.7*VDD Nominal) to Low ( <0.2*VDD).  Please refer to section 5.19.8 in the Data sheet of WL1831 ( SWRS152).

    dBFS unit is used in ADC / DACs parameters. In your case, it is meant for ECNC ( please refer to the diagram in your 1st post).

    If you use a 16 Bit ADC then the theoretical Dynamic range  = 96dB. If you apply this one to Full scale, if the highest level is set at 0dBm and the lowest level would be -96dBm.

    Audio ADCs are available from TI. The following is the link. You can check dBFS in those data sheets.

    dBm is the Unit used for measurement/ specify RF Power. It is a Decibel unit for Watts. For example, WL1831 Tx Power Output specified as 17.3 dBm. Please refer to Table 5.7 of the WL1831 data sheet.

    Thanks,

    PM