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DAC8581 overheat

  • Simone Caron
    Posted by
    on May 17 2012 05:54 AM
    Prodigy40 points

    Hi,

    I am trying to use DAC8581 for my project, but i have a strange overheat problem.
    Sometimes the DAC work perfectly and sometime becomes very hot and work very bad without changing anything in the circuit.
    The IC is soldered in my own board, the supply is 3,3V for digital and +5V/-5V for the analog and Vref is 5V, the ground is separate.The output is connected to a OP177 in buffer configuration. I have place a 100nF capacitor between DGND-DVDD, AVss-AVdd, AVss-AGND, AVdd-AGND, Vref-AGND.
    For the analog supply i using 78L05 for 5V and 79L05 for -5V.
    I do not know why the IC becomes hot, i've already broken 2 DAC for the same problem!
    Maybe there's a mistake with a supply part?
    Thanks a lot
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  • Tom Hendrick
    Posted by
    on May 17 2012 06:22 AM
    Guru86210 points

    Hi Simone,

    Welcome to our forum!  The problem you are having with the DAC8581 may be caused by a difference in ground potentials between the analog and digital portions of the device.  Please tie the AGND and DGND together and let us know if that resolves the problem.

     

    Regards,

    Tom

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  • Simone Caron
    Posted by
    on May 17 2012 07:10 AM
    Prodigy40 points

    Hi,

    I have measured the potential and is of a few mV.

    I try to follow your advice. If i put a SMD ferrite bead between two graund plane in order to avoid noise may be cause problemes? or it is useless?

    Thanks

    Report Abuse
  • Tom Hendrick
    Posted by
    on May 17 2012 07:59 AM
    Guru86210 points

    Try a solder short between pins 5 and 6 to start with.  Use a 0ohm resistor instead of FB between the ground planes.

     

    Regards,

    Tom

    Report Abuse
  • Simone Caron
    Posted by
    on May 17 2012 13:40 PM
    Prodigy40 points

    I soldered a 0 ohm resistor between the two ground plans near the DAC but nothing has changed.
    Now i replaced the IC and it work fine, even if it becomes slightly warm.
    I'll try to see in the following days if it will burns or not....

    Report Abuse
  • Simone Caron
    Posted by
    on Jun 14 2012 10:13 AM
    Prodigy40 points

    Hi,

    After several weeks of perfect work

    today the DAC became hot as before :(

    So the problem is not solved

    Report Abuse

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