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characterization of 12bit DAC MCP 4725

Question asked by akash.j on Oct 12, 2012
Latest reply on Oct 18, 2012 by AndyR

I am trying to characterize 12bit DAC MCP4725 and i am trying to find DNL(Differential Non Linearity Error).

I increased the input code till 4000 and i got the DNL(in LSB) which i have plotted on a graph and i have uploaded it here.

The problem is, if you observe the graph closely, then at some values we are getting very high DNL values (greater than 1LSB) and the values are increasing after some gap and very periodically and reaching upto 12LSB(I am talking about the vertical tall lines whose height goes on increasing in the graph and which come after some periodic space) and these high values are coming after a gap of every 128 or 129 codes hence i say very periodic.

 

Graph1.jpg

 

The question is

  1) Am i getting the wrong result if so then what do you think is the problem and how do we remove it.

2)If i am getting the right result then how do i calculate the DNL error as the Datasheet Says (0.2LSB typical and 0.75LSB max) and i am getting DNL upto 12LSB.

   

Pl help and refer to the attached image.

Thanks

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