A B C D E REVISION HISTORY ECO REV __ 2 DESCRIPTION APPROVED DATE PRODUCTION JESUS R. 02-23-11 4 4 C1 0.1uF VIN JP2 LDO 2 SW 6 5 7 11 VCC2 EN2 OUT2 R6 100K FB2 C4 10uF 6.3V 0805 C13 OPT 0402 R2 31.6K 1% 4 2 VOUT1 3.3V / 300mA C11 0.1uF 10V E3 GND R3 8 10K 2.5V 3 9 R4 10K 3.3V NPG FB GND OFF EN/UVLO R1 10K 1 2 3 ON 3 E2 D1 PD3S140 DA 13 OFF 1 BOOST 1 2 3 ON VIN JP1 3.3V 10V C3 1uF 50V 1206 R8 OPT GND E4 C2 10uF 63V 3 GND + NPG TRANSIENT TO 55V 3.3V 1 E1 12 VIN 5V - 36V L1 10uH NRH3012T100MN 10 U1 LT3645EMSE E5 R5 21.5K 1% C5 2.2uF 6.3V VOUT2 2.5V / 200mA C12 0.1uF 10V R7 10K 1% E6 GND E7 2 2 NOTE: UNLESS OTHERWISE SPECIFIED 1. ALL RESISTORS ARE 0402. ALL CAPACITORS ARE 0603. 2. INSTALL SHUNTS AS SHOWN. CUSTOMER NOTICE 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. 1 TECHNOLOGY JW JESUS R. TITLE: SCHEMATIC A B C IC NO. REV. LT3645EMSE N/A SCALE = NONE 1 STEP-DOWN REGULATOR WITH LDO SIZE THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only 2 DEMO CIRCUIT 1428A DATE: 02-23-11 D SHEET 1 E OF 1