R3 215K C1 6.8uF 50V L1 6.8uH R4 + CIN1 10uF 63V E2 100K E5 ON OFF 2 3 C12 100pF R6 10.5K C11 10nF R7 42.2K C13 SHDN/UVLO 1 VC 2 FBX 4 RT 5 SYNC 3 SS VIN INTVcc 10 Opt. 8 Q1 SI7850DP C10 4.7uF 10V GATE 7 SENSE 6 SYNC PDS1045 L2 6.8uH 4 C3 100uF 6.3V 123 C4 100uF 6.3V C5 100uF 6.3V E3 E4 R5 0.01 1W VOUT 5V @ 3A GND R1 42.2K 1% E6 R8 10K GND GND 5678 11 0.1uF C8 9 VIN 4.5V - 36V D1 10uF 50V 10uF 50V GND JP1 RUN C7 U1 LT3757EDD 1 VCC E1 R2 20.0K 1% E7 CUSTOMER NOTICE LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. CONTRACT NO. APPROVALS DRAWN ENGINEER DATE J. Wu 10/3/07 W. Gu 10/3/07 TECHNOLOGY TITLE Friday, January 30, 2009 LT3757EDD High Efficiency SEPIC Converter CHECKED APPROVED 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 Fax: (408)434-0507 SIZE CAGE CODE SCALE: FILENAME: DWG NO REV DC1341A SHEET 1 A OF 1