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AD7903 calculate LSB

Question asked by dirkson on Oct 1, 2014
Latest reply on Oct 5, 2014 by dirkson

Hello,

 

the question is about the AD7903 http://www.analog.com/static/imported-files/data_sheets/AD7903.pdf

 

I have calculate the LSB with

 

u_LSB = u_in / 2^n

 

The input voltage (full scale) is u_in = +-5V when Ref=5V and resolution of 16 Bit.

 

=> u_LSB = +5V / 2^15 = +152,58uV

or

     u_LSB = +10V / 2^16 = +152,58uV

 

But in the datasheet the u_LSB is 38.15uV:

 

7903_LSB.png

Where is the mistake?

 

Thank you in advance.

 

Best regards

 

Dirk

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