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Original question:

PCM4220: Overload issue, and MCKI question.

PCM4220: Reference voltage

Jeff Xie
Intellectual 1780 points
Part Number: PCM4220

Hi team,

Customer want to check what is the value of internal reference voltage? Thanks.

  • 0
    TI__Intellectual 1780 points

    Also what is the transferfunction of it? Thanks.

  • 0 in reply to Jeff Xie
    TI__Guru 62035 points

    Hello,

    I'm having a little trouble finding the exact value of the internal reference voltage, but you can probe the VREFL/R outputs with a high-z DMM to measure the value.  Based on the information I could find, it's likely around 2.8V.  

    The output will be a binary two's complement output which is standard for I2S and other Audio Serial Interface outputs.  The full-scale input range is +/-2.8Vp or 5.6Vpp.  Therefore, when IN+ is at the positive peak of the waveform and IN- is at the negative peak, you'll get 0x7FFFFF, and when IN- is at the positive peak and IN+ is at negative peak, the output will be 0x800000.  At mid-scale you'll get 0x000000, and +/- 1 LSB from there would be 0x000001 and 0xFFFFFF.