Adjust the DC votage to LOC111

Discussion in 'General Electronics Chat' started by superway, Feb 10, 2012.

  1. superway

    Thread Starter Active Member

    Oct 19, 2009
    128
    0
    Hi,

    I enclosed a schematic by hand drawing.
    I applied 10vdc at R1 and tried to adjust R2 to bring TP1 down to 1.3Vdc to get the correct voltage, but somehow and sometimes the TP1 can not go low 1.3vdc, it always about 1.8v or 1.9v that is lowest point even I tried to adjust the R1 all the way down and noticed a small click on R2. According LOC111 specs, can be 1.2V - 1.4Vdc on LED voltage drop
    http://www.clare.com/home/pdfs.nsf/www/LOC111.pdf/$file/LOC111.pdf

    Is that problem related to linear optocoupler? On data sheet, it shows K3 sort Bin table with Bin A to Bin J version, and what all the numbers on second column stand for? should Bin A, Bin B, Bin C... change different reading?

    Please help. Thanks
    Thanks
     
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  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    What U1A is suppossed to do?
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,649
    2,348
    Hello,

    Did you read the application note for this chip?
    I have attached it.
    Take a look at page 3 for the schematic.
    It looks a bit different as the schematic you posted.

    Bertus
     
  4. superway

    Thread Starter Active Member

    Oct 19, 2009
    128
    0
    On data sheet, What does it mean below:
    K3 Sorted Bins​
    Bin A = 0.550-0.605
    Bin B = 0.606-0.667
    Bin C = 0.668-0.732
    Bin D = 0.733-0.805
    Bin E = 0.806-0.886
    Bin F = 0.887-0.974
    Bin G = 0.975-1.072
    Bin H = 1.073-1.179
    Bin I = 1.180-1.297​
    Bin J = 1.298-1.426

    Does one of it affect the voltage reading on my schemactic if we change from one to antoher one?

    Thanks
     
  5. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    K3 is the transfer gain between the input and the output (see Electrical Characteristics). It means the input current versus the output current can be different, depending upon the device you get.

    And as bertus noted, use the input circuit shown in the Application Note for proper operation.
     
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