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ADuM240E driving full H-Bridge

Dear Support
We use the ADuM240E0 to isolate the signals driving a H-Bridge
we have several hundreds devices out in the market.
Recently we have received defect ones where the Vdd1 or Vdd2 has a short circuit.
We have no explanation for this.
Any suggestion from your side where we can search?
Thanks, best regards Greg

Vdd1 is 3.3 V
Vdd2 is 5.0 V
both voltages are protected by TVS diodes
Via..d  are driven from a PIC micro-controller (10 ohms in the line)
Voa, b  are driving directly a SN74HC86 Logic
Voc,d  are the enable signals for the H-Bridge driver chip
None of the surrounding components are damaged.
Only short of Vdd1, mostly

  • Hi Greg, 

    The VDD1 and the VDD2 sides of the ADuM240E are independent pieces of silicon. If one side is damaged, it will not effect the other. My first assumption would be that there are separate events causing damage. 

    Voltages above the Absolute Maximum listed in the datasheet may cause permanent damage. First check would be to see if there is a condition causing the Abs Max values to be violated. Also it looks like these pins may be exposed to the outside world through the P5 connector. The VIA/VIB/VIC/VID pins of the ADuM240E are rated for +/-4kV HBM ESD. Its possible the ADuM240E pins are seeing a higher stress than expected.