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TLV320ADC6140: Guidance on 32-bit Floating Point Recording

Mitchell
Expert 4915 points
Part Number: TLV320ADC6140
Other Parts Discussed in Thread: ADC6140EVM-PDK

Hi Team,

My customer is working on a new project and is planning to use the TLV320ADC6140. They are looking for some guidance on how to implement 32-bit floating point recording. Wanted to understand if we have any reference designs or application notes that could be helpful here?

Thanks,
Mitchell

  • 0
    TI__Guru 64205 points

    Hi Mitchell,

    The ADC6140EVM-PDK will enumerate as a USB audio device and by default it is setup for 8-channel TDM 32-bit mode.  It could be used as a good starting point for understanding the data transmission between the audio host processor and the TLV320ADC6140.

  • 0
    TI__Expert 6995 points

    Mitchell,

    We do not have a specific app note on recording 32-bit floating point. Typically, ADC's send twos complement signed data centered around the common mode voltage. This converted code is based on the full scale range of the ADC and it is proportional to the reference voltage. If the PGA is used to boost the signal, then it must be taken into account. Thus, the converted code must be multiplied by Vref and divided by PGA value to convert the code to the input voltage. To convert to floating point, we want this number to lie between the range of -1 to 1. For a two's complement number, we divide by 2^(ADC_resolution-1). In summary, the ADC floating point value would be:

    float_value = (ADC_Converted_Code * VREF) / (PGA_Gain * 2^(ADC_Resolution-1))

    This blog post explains the derivation of this equation.

    These app notes also show this equation:

    • How the voltage reference affects ADC performance (Part 1), (Part 2)

    best regards,

      Pedro