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AD7799 Excessive current draw?

Question asked by BER520 on Apr 23, 2012
Latest reply on Apr 24, 2012 by BER520

I am using the AD7799 in a weigh scale application.  The weigh scale works; however, the scale has exhibited odd behavior during testing.  Basically, the circuit starts operating normally but if you move your hand close to the circuit board or the board experiences a static shock, the circuit starts to draw excessive current.  The circuit draws between 30 - 35 mA with the load cells connected during normal operation.  When the board draws excessive current; it peaks around 500 mA and then settles to about 250 mA.  To prevent the board from burning out the power is quickly removed follwoing the current spike.  Upon reapplying power, the board draws normal current again between 30 - 35 mA.   The circuit implements ESD protection and the PCB layout was done to minimize noise.  Any advice would be helpful.  If no solution can be found soon, the board will have to be re-designed.