Hello all!
I have several diodes IN5552.
After the PN, there is another number on the diode 0640 or 0631.
Can't find any information what it means...
I hope someone can help.

 

It's probably a date code or batch number. Often the datasheet details the marking but I couldn't find any such information for this diode.

 

I agree with @AlbertHall

the only designators that matter are below. Anything else may be batch or date codes: