ADC 0804 testing problem

Discussion in 'The Projects Forum' started by Vex89, Jun 8, 2012.

  1. Vex89

    Thread Starter New Member

    Jun 8, 2012
    1
    0
    Hello everyone!

    I'm sorry for my bad english :). I have a few questions about a problem I can't solve.
    I have created a program in Labview to calculate errors of 8 bit ADC 0804. Program is based on servo-loop method. The converter is in free running mode and the program is ploting all voltages from 0 to 255. Converter is working fine untill Vin reaches 4.4V (Code 220), after 4.4V converter doesnt work fine (I'm getting quite a big error) untill the program reaches code 255 (the last code is ploted properly). The image will make things more easy to understand (lower graph is error plot-plotting Vreal-Videal). Vcc is 5.12 V and I was thinking that the issue could be in fact that voltage measured on pin 9 is 1.48 and it should be 2.56 V.
    Could anyone help me with this problem?
    And my second question would be how to determine conversion time of this A/D converter?
    Thank you!
     
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