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    Right shifting the ADC value

    Hi, it kinda confused me, what is right shifting for in adc computation. I have read in one article that right shifting helps to achieve the full scale voltage, what does that mean?

    •   Alt7th November 2016, 06:19

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    Re: Right shifting the ADC value

    Hi,

    Right shifting of an unsigned value is the same as divide by 2. (Loosing the LSB information)

    I have read in one article .... what does that mean?
    --> then show us the article. Often the context explains that "snippet of information".

    ******

    It's like saying: "I've read in some article that values above 120 can be dangerous".
    This information is only useful when you know what the rest of the text is talking about.

    Klaus


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    •   Alt7th November 2016, 07:27

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    Re: Right shifting the ADC value




    •   Alt8th November 2016, 05:29

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    Re: Right shifting the ADC value

    Hi,

    First important thing is: it is a delta sigma ADC, which has very unique step size (low DNL, low INL).

    Then - only with low input signal - they use half or quarter of the usual reference:
    * 1.25V or 0.625V instead of 2.5V. Therefore the the full range input is only 1/2 or 1/4 of the usual range, but the digital value is multiplied by 2 or 4 (= shifted 1 or two buts left)
    * to compensate for the left shift they shift the digital value right.

    This just means that the digital value does not alter, but the accuracy is improved.

    ******
    The usual way is to amplify the input signal to fit it to the ADC input range, then afterwards the software takes care of the increased digital value.
    The Maxim solution has the benefit, that there is no need for an external amplifier, and the software doesn't need to compensate for the modified digital value.

    Klaus


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