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ADS1178: maximum instantaneous noise level of the ADC

Part Number: ADS1178

Good afternoon. Now, I am considering the possibility of using your ADC in the development of our company's devices. The value of the maximum instantaneous noise level of the ADC is crucial when choosing an ADC. What parameter in the ADC datasheet is responsible for the maximum instantaneous noise level of the ADC? By the maximum instantaneous noise level of the ADC, I mean the value by which the true value of the sample can change.

  • Hello Valeriy,

    Welcome to the TI E2E community!

    The ADS1178 SNR is primarily limited by quantization noise.  For a 16b converter, the ideal SNR is:

    SNR= 6.02N+1.76 = 6.02*16+1.76 = 98dB ideal.

    The ADS1178 SNR is specified at 97dB typical.

    If looking at a DC input level, the peak-to-peak noise is 1LSB.  When using a 2.5V reference, this is equal to 76.3uVpp.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • Good Afternoon.

    I wanted to clarify whether I understand correctly that maximum instantaneous ADC noise will be calculated as

    where FSR - Full Scale Range;

    r  - ADC's resolution.

    Thanks for the answer.

  • HI Valeriy,

    Yes, you are correct.  The peak-to-peak noise for ADS1178 is 1LSB.  And 1 LSB is equal to the equation that you have shown.

    FSR=2*VRef

    r=16

    LSB = 2*2.5V/(2^16-1) = 76.3uVpp

    Regards,
    Keith