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PCM1690-Q1: ADC and DAC compatability

mike lacroix
Prodigy 80 points
Part Number: PCM1690-Q1
Other Parts Discussed in Thread: ADS1672

I am developing a new product that uses an ADS1672 ADC on the input. For the output I am using a PCM1690-Q1 DAC. I was reviewing my design when it hit me that the input ADC converts the incoming signal using a 2s compliment value for input signals that are negative. I then scoured the data sheet for the PCM1690-Q1 uses the same data format but there is nothing in the datasheet that depicts the format of the digital input. I would hate to just assume that the digital output format of the ADC and DAC are the same and find out that the system doesn't work. How do I find out what the digital data format should look like and I don't mean the serial communications. Any and all help appreciated.

Regards,

Mike Lacroix

  • 0
    TI__Guru 57800 points

    Hi, Mike,

    The digital input data for the  PCM1690-Q1 must be in binary 2s complement with MSB first. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 80 points

    To make sure that I fully understand, it appears that the 2s compliment values from the ADC for all voltages where the input signal is "negative". In the case of the ADC when the In- voltage is more positive than the In+ voltage. Therefore, if the input voltage was, say -2V the ADC output would be a 2s compliment value. Then if I directly transferred that 2s compliment value into the DAC the output voltage would be -2V. Correct?

    Regards.