TPD12S521: Part marking questions

Part Number: TPD12S521

Hello, I have a part I need help with identifying the markings on. Can you help me identify the meanings of line 2 and 3? I am trying to fine lot/date code information on this part. Thank you for your assistance!

TPD12S521DBTR

Markings:

Line 1: PN521

Line 2: 31TG4

Line 3:   A2Y7