Group.
I am interested to find out peoples opinions on a particular trend we've
seen time and time again on most switch mode PSU's. It seems that once a PSU is
warm its earth leakage decreases and its EMC emission performance decreases
(i.e. it gets noisier). This would suggest that there is some sort of thermal
effect, probabaly in the Y caps, that reduces their capacitance.
Has anyone done any work in this area or can anyone explain the physics of this
change. Is it as simple as expansion of the dielectric or is it more complicated
than this? Any thoughts or opinions would be greatly recieved.
Many thanks in advance,
Duncan Hobbs
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