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Why AD5780/90 get shortage on VSS

Question asked by Nedzad on Jun 6, 2014
Latest reply on Jun 24, 2014 by Nedzad

We've bought 3 evaluation boards (1 pcs EVAL-AD5790 and 2 pcs EVAL-AD5780) and we built 10 own DAC-boards mainly following the eval board schematic.
In general the DAC works perfect and we're very satisfied with the performance.
Unfortunately 3 of 13 chips got damaged after short usage. One AD5790 died on the eval board and 2 AD5780 died on our boards. In all cases we measured a low impedance path from VSS to AGND.
We power the boards with Agilent
E3631A power supply setup for +/- 10V and VCC is setup to 3.3V. VREFP and VREFN are jumpered to +/-5V. The output amplifier (AD8675) is connected in unity gain mode with amplifier input bias current compensation.
Any idea what reason could drive these chips to die?