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ADC internal ref accuracy compared to VDD/4 as ref

bart

Hi, I read a couple of post that asked about the accuracy / tolerance of the internal REF, and the answers mention it's included in the gain error.

This made me wondering: if VDD would be perfectly stable, how would using VDD/4 as reference compare to using the internal 0.6V REF? What gain error would that result in?

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  • 0

    Depends more on whether the signal is ratiometric or not. If the signal is unrelated to VDD, for example an external device like a tiny photocell which generates a voltage completely independent of nRF52 VDD then the internal reference will always be better. However if the signal voltage is related to VDD such that it rises and falls as VDD rises and falls (say a potentiometer or load cell which uses VDD as the voltage source) then VDD/4 will be more stable as the reference VDD/4 tracks the excitation voltage.

  • 0 in reply to hmolesworth

    Yes, that makes sense. However, suppose the signal is unrelated to VDD, but we have a perfect VDD of 3.3V, then what kind of gain error would I get? Basically I'm trying to find out what the error of the internal ref is, separately from the gain error.

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  • 0 in reply to hmolesworth

    Yes, that makes sense. However, suppose the signal is unrelated to VDD, but we have a perfect VDD of 3.3V, then what kind of gain error would I get? Basically I'm trying to find out what the error of the internal ref is, separately from the gain error.

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