UF Package 28-Lead Plastic QFN (4mm × 4mm) Reference LTC DWG # 05-08-1721 Rev A) 0.70 ± 0.05 4.50 ± 0.05 3.10 ± 0.05 2.64 ± 0.05 (4 SIDES) PACKAGE OUTLINE 0.20 ± 0.05 0.40 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 ± 0.10 (4 SIDES) 0.75 ± 0.05 R = 0.05 TYP PIN 1 TOP MARK (NOTE 6) PIN 1 NOTCH R = 0.20 TYP OR 0.35 × 45° CHAMFER BOTTOM VIEW—EXPOSED PAD R = 0.115 TYP 27 28 0.40 ± 0.05 1 2 2.64 ± 0.10 (4-SIDES) (UF28) QFN 0106 REVA 0.200 REF 0.00 – 0.05 NOTE: 1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE, IF PRESENT 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 0.20 ± 0.05 0.40 BSC