We are experiencing some problems with the ad7328 ADC converter. The problem is that the ad7328 burns out. This happens after some period of time (from 2 to 8 hours ) of perfect working of the converter (we have checked this with many converters).
We have followed all the design guidelines included in the datasheet and we do not exceed the maximum absolute ratings. Also, the analog inputs are buffered and Schottky diodes are placed in series with Vdd and Vss supply signals. The only difference that we have been seen is that a 100nF capacitor is placed in the REFIN pin instead of the recommended 680nF capacitor. Could this capacitor be the reason of the problem?
In order to find out where the problem can come from, we have tried to compare a burned adc with a good one by meassuring the impedance between the power pines and GND. We have seen that in the burned adc the Vcc to GND impedance decreases significantly. Is the any other consideration not included in the datasheet that we should take into account?
Thanks in advance.