5 4 3 2 1 REVISION HISTORY ISP ECO REV _ 2 DESCRIPTION APPROVED DATE PRODUCTION WALKER B. 03-26-12 ISN D R1 5 R12 1M R4 E5 4 OPT SYNC 3 2 1 SYNC E9 C GND GND 6 1 23 JP1 24 17 2 E6 IMON 3 E7 C7 1uF 0603 25V FB1 L2 4.7uH VEMI C3 4.7uF 50V 1206 R8 60.4k 7 8 EN/UV SW SYNC SW IMON SW ICTRL ISP INTVCC ISN TR/SS BIAS RT PG PGND FB C4 0.22uF 16V 0603 13 VIN R5 0.02 1206 14 ISP R6 15 21 C5 OPT ISN VOUT E3 VOUT 3.3V / 2.5A C6 47uF 10V 1210 E4 GND 0 C R7 22 0 18 R9 19 R10 20 R11 412k 49.9k 1Meg C9 4.7pF B E10 PG C10 4.7uF 50V 1206 NOTES: UNLESS OTHERWISE SPECIFIED 1. ALL RESISTORS ARE IN OHMS, 0402. ALL CAPACITORS ARE IN MICROFARADS, 0402. APPROVALS LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APP ENG. APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. TECHNOLOGY JW THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 4 3 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only WALKER B. TITLE: SCHEMATIC IC NO. DATE: REV. LT8611EUDD N/A SCALE = NONE A 42V, 2.5A MICROPOWER SYNCHRONOUS STEP-DOWN REGULATOR WITH CURRENT SENSE SIZE 5 L1 4.7uH PGND CUSTOMER NOTICE A 16 VIN 9 B C8 0.1uF BST N/C ICTRL VIN N/C GND C2 4.7uF 50V 1206 N/C E2 0 1206 12 22uF 63V SUNCON 63CE22BS 11 + C1 U1 LT8611EUDD GND VIN 25 VIN E1 3.8V - 42V N/C D R3 OPT 10 R2 OPT 2 DEMO CIRCUIT 1750A Tuesday, April 10, 2012 SHEET 1 2 1 OF 1