Alan B. Pearce <A.B.Pearce <at> rl.ac.uk> writes:

> I wonder why these pop. Perhaps adding some diodes to ground and supply for 
> protection required ? 

Every USB device that has an external connection to something else (wall wart,
DUT, circuit under test etc) is prone to this. The ground bounce from external
loads gets them. Diodes will not likely help. Resistors in the ground line might
help (22ohms or such).

Peter 




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