Test circuit for dac ic (0800)

Discussion in 'The Projects Forum' started by dandrous, Mar 2, 2015.

  1. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    i would like to develope a DAC 0800 ic tester..how can i test a dac ic?
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    Build an 8-bit binary synchronous counter circuit clocked by a 555 timer circuit and apply the 8 bits to the input of the DAC.
     
  3. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    how can i compare the output and input..to find error?
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    Measure the output on a digital voltmeter.
     
  5. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    sory..i just want to make it as a ic tester equipment..just like an ic tester..
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    What are you testing?
     
  7. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    how can i relate the input applied to dac and output obtained from dac...i know that for each binary input there will be different voltage levels ..so my idea is to find any deviation from the output voltage for particular input can be considered as a error
    for example
    for a good working dac when ever i apply 10000000 at input suppose there will be an output 9v
    for another ic (faulty one) if got 5v with all same parameters that is an error..
    so i want to check all the 8bit input combinations inorder to ensure all combinations are working
     
  8. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    Put eight toggle switches on the digital inputs. Read the output voltage on a DVM.
     
  9. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    mrchips i already mentioned that i want to devlope it as an equipment ..it shoud be userfriendly..icluding only one "test "switch is prefered...
     
  10. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    You mean to say you wish it to be an automated process. You didn't say that before.

    Output 8 bits from a computer and read the voltage using an ADC or digital voltmeter with a minimum of 12-bit resolution.
     
    dandrous likes this.
  11. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    why 12bit adc? 8bit adc is enough?
     
    Last edited: Mar 2, 2015
  12. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    How are you going to measure ½-bit errors? You want the ADC to be better than the DAC by at least 2 bits.
     
    dandrous likes this.
  13. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,648
    764
    Something I did when I started to deal with DACs was to run them driven by a counter and check the output with a scope for linearity.

    Not sure about fine details but I could see easily how it worked. More or less what you do when implementing an R2R network.
     
    dandrous likes this.
  14. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    how i can test linerity?
     
  15. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,790
    The same way you test any dataset for linearity. If the points are within some small deviation from the equation of a straight line then the dataset is linear. You test this by selecting a sample and calculating the mean deviation from the equation of the line and the variance of those deviations.

    The freeware language `R' is really helpful with this stuff.
    http://www.r-project.org/
     
  16. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    check the circuit i have drawn ..it is for testing a dac ic..the concept is that a dac ic convert digital input to analogue and this analogue is passed to the adc..and the obtained digital output is compared with the input ..when the sequence input and output is same its clocked the flipflop to count next state and so on..i wish to use johnson counter when ever there is a mismatch between input and output the counting is stopes and fail indication led is lights..when counting a set of sequence completed it is driven to a pass indication led(i forgot to add a not gate besides that led leav it)..please help me to develop the circuit..and tell me any errors in this..
     
  17. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    The choice of an 741 in your circuit is not so good.
    It has quite some offset and noise.

    Bertus
     
  18. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
  19. dandrous

    Thread Starter New Member

    Mar 2, 2015
    22
    0
    i wil replace it with other opamps..is there any other problem>?
     
  20. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    Why do you post such large images?
    I did reduce it to about 600 Kb, but you have put up the 2.5 Mb again.
    Not everybody is pleased with that huge image.

    Have a look here to select an opamp:
    Op Amps

    Bertus
     
Loading...