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How to choose Reference for ADC

Question asked by Tarzan on Jun 28, 2011
Latest reply on Jun 29, 2011 by Tarzan

Hi everyone,

 

I'm wondering how to select a reference IC when I design ADC sometimes.
For expample, looking at AD7918, 10bit-ADC external referene and the gain error itself is 0.5LSB MAX.
Reference accuracy is said to be less than 1% according to the comment of datasheet.

Ive attached a file on this mail.Please refere to it.
But I'm wondering that the accuracy of reference is 1% sounds larger.
Because the resolution of 10bit is equivalent to 0.1% and the gain error of this device is only 0.5LSB(0.05%).
Please give me advice on the coneection between the gain error and the accuracy of reference voltage.
(In this case, reference noise and tempareture coefficient are not considered to make it simple)
And one more thing, I want to know how to estimate source current of ADC refinput to choose right reference IC.

 

Tarzan

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