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ADuM4160 breaks/burns

This is our USB interface to a PIC32MX microcontroller. Left side is powered by USB, right side with 5 V. We use this design since some years and never had problems with it. But the last few weeks, we encounter that some ADuMs get very hot and don't work or even burn and break their package. Any idea, whether this is a bad batch or something is out of spec? Photo of PCB assembly with a broken IC below ...

  • Hi Schoenf,

    Can you provide any additional information about whether the operating conditions would have changed in some way recently?

    Reviewing your schematic, I can say that unfortunately the design does have the ADuM4160 operating out of specification, beyond the absolute maximum ratings in fact for SPD and SPU pins. They are connected to VBUS1/VBUS2 = 5V, when the max allowed voltage is VDD1/VDD2 + 0.5V (VDD1/VDD2 are 3.3V).

    Best regards,

    Conal

  • You're right! I just figured this out by myself some minutes ago. It is not my design but copy&pasted since some generations of PCBs and never led to a problem. Until now. We will change this! Thank you, anyway!

    Greetings

    Jochen