Have been working with this part for a while on several designs without any issues. Recently got a set of samples in from a CM and two of the four examples of this part failed after a couple of days of operation, (haven't had a chance to perform a deep analysis yet, one parts output voltage began to plummet after a few seconds of operation, the second seems to be going into pulse skipping mode at 10 Hz after warming up - (they both get much warmer than normal).
In the above photo the part on the left is the failed component and the part on the right is a functioning example which replaced it - (the parts are from two different era's).
My question is : do the non-text dash like markings denote some sort of date code that might be useful in analyzing this issue? They are different between the two and they appear to follow some sort of logic.
Thanks much