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ADC081C021: May we know how to read voltage from ADC081C021?

Part Number: ADC081C021

Hi Sir

May we know how to read voltage from ADC081C021?

which register we can read and check currently voltage?

                                                                Bogey

  • Hello,

    The register information can be found starting on 17 of the ADC081C021 Datasheet

    The particular register you are looking for is called " Conversion Result" and its description can be found in page 18 of the datasheet

    Regards

    Cynthia

  • Hi Cynthia

    From DS page 16. there is 12 bit code, as we know  ADC081C021  is 8 bits ADC. why there spec is 12bits?

    Sorry for i don't under stand this description.

    The output format of the ADC081C021 is straight binary. Code transitions occur midway between successive
    integer LSB values. The LSB width for the ADC081C021 is VA / 256. The ideal transfer characteristic is shown in
    Figure 23. The transition from an output code of 0000 0000 0000 to a code of 0000 0000 0001 is at 1/2 LSB, or a
    voltage of VA / 512. Other code transitions occur at intervals of 1 LSB.

                                                                                      Bogey

  • Bogey,

    Let me try to explain

    LSB = VA /(2^N),

    where

    VA is the full scale range and is normalized and N = 8 bit resolution. For this example let's say that VA= 5V

    Thus, LSB = 5V / (2^8) = 5V / 256 = 19.5mV

    This means that at every step of 19.5mV, that output code will increase by 1.

    Each code increase represents an increase of 19.5mV

    Now, the statement you referred to is describing that the first code increase, and ONLY the first code increase will be seen at LSB/2 instead of a one LSB.

    Using the example, this means that the first code increase will not be seen at 0 + 19.5mV, but instead it will be seen at 0+ LSB/2 = 0+9.7mV

    In the datasheet, it was trying to explain thist in general terms by saying that the first code increase will be seen at VA / 512. This is from the original LSB equation, trying to solve for half LSB

    Half LSB = VA / (2^ 8) / 2 = VA / (256) / 2 = VA /512

    Which calculates out to be same as our example

    VA / 512 = 5 / 512 = 9.7mV

    Does this clarify?

    Regards

    Cynthia