SEMICONDUCTOR KTC4521F MARKING SPECIFICATION TO-220IS PACKAGE 1. Marking method Laser Marking or Ink Marking. 2. Marking 1 K 2 C4521F R 3 No. 2004. 10. 26 416 4 Item Marking Description KEC K KEC CORP. Device Name C4521F KTC4521F hFE Grade R R, O, Y Lot No. 416 Revision No : 0 4 Year 0~9 : 2000~2009 16 Week 16 : 16th Week 1/1