EFM8SB2 Datasheet, PDF (38/49 Pages) Silicon Laboratories – The EFM8SB2 highlighted features are listed below

7.3 QFN32 Package Marking
EFM8SB2 Data Sheet
QFN32 Package Specifications
EFM8
PPPPPPPP
TTTTTT
YYWW #
Figure 7.3. QFN32 Package Marking
The package marking consists of:
• PPPPPPPP – The part number designation.
• TTTTTT – A trace or manufacturing code.
• YY – The last 2 digits of the assembly year.
• WW – The 2-digit workweek when the device was assembled.
• # – The device revision (A, B, etc.).
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