A/D Converter

Discussion in 'Homework Help' started by hncelectronics123, Jun 4, 2008.

  1. hncelectronics123

    Thread Starter Member

    May 23, 2008
    10
    0
    Hello again Guys

    Another question id like to ask is;

    I have an output from an analogue device of 0.699mV

    Using An 8bit A/D converter work out the output.
     
  2. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    What is the ADC range? Is the ADC linear or non-linear?

    Dave
     
  3. hncelectronics123

    Thread Starter Member

    May 23, 2008
    10
    0
    The ADC is Linear yes.

    The only other information i have on it is

    Number of bits = 8
    Input to achieve ful scale output = 4 volts

    Does this help?

    Thanks
     
  4. hncelectronics123

    Thread Starter Member

    May 23, 2008
    10
    0
    Ok i have worked out the Resolution of the A/D converter.

    8 bits = 256 codes

    full scale output = 4v

    so....... 4v/256codes = 15.62mV



    Can anybody work out the final output of the A/D converter if the input is 0.699mV

    Thanks in advance
     
  5. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    In you first post you say 0.699V and in the last 0.699mV.
    With 0.699V ( that is 699 mV ).
    Per step you calculated 4 V / 256 = 15.625 mV
    If you divide 699 mV / 15.625 mV you will get 44.736.
    Depending on the accuracy you will get 44 or 45 as a digital value.

    Greetings,
    Bertus
     
  6. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    Yes that is the ADC range.

    15.62mV is correct as the resolution.

    Are you sure you want to know the output for 0.699mV? 0.699mV is considerably less than the 15.62mV resolution of the ADC; therefore an input of 0.669mV would not register a reading at the output, i.e. the output would be 00000000

    If it is 0.699V and not 0.699mV, then the answer is as bertus has explained of 45 (in base 10) or 00101101 as an 8-bit binary output.

    Dave
     
  7. hncelectronics123

    Thread Starter Member

    May 23, 2008
    10
    0
    Thanks alot Yeah my mistake with the mv, v thing. been along day.

    So, lets say that the output of the analogue/digital converter is 45.
    I understand that this is the output but can this be displayed in a binary format, Such as 11010110


    Thanks very much
     
  8. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    No problem, thanks for clearing it up.

    45 (decimal) is 00101101 (binary) - this is the 8-bit output of the ADC for an input voltage of 0.699V.

    Dave
     
  9. hncelectronics123

    Thread Starter Member

    May 23, 2008
    10
    0
    Many thanks for all your help!!!!!!
    Sorry for the mistake, you are right with 0.699v.



    Once again thank you very much
     
  10. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    No problems. Lets us know if you have any further queries.

    Dave
     
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