5 4 3 2 1 REVISION HISTORY ECO REV ---- * SEE QUICK START GUIDE D VIN 4V-36V R1 * E3 D5 GND PWM1 1N4448W (Opt) E4 20 3 1N4448W L1 10uH Sumida COUT1 2.2uF 16V 5 6 16 VIN VIN SHDN PWM1 PWM2 BOOST1 BOOST2 VIN D6 TSSOP20-FE/CB 1N4448W (Opt) 11 E5 PWM2 D2 8 1N4448W 1 D3 OUT1 OUT2 10 C1 0.22uF X5R 4 SW1 SW2 7 2 LED1 LED2 9 17 REF B240A L2 10uH Sumida C2 0.22uF X5R COUT2 2.2uF 16V D4 B240A Q1 Si2312BDS (Opt) REF R2 0 1206 R6 10k (Opt) R8 19 (Opt) Q2 Si2312BDS (Opt) REF VADJ1 VADJ2 12 VC2 13 VC1 C R3 0 1206 R5 (Opt) R4 (Opt) 18 GND APPROVED DAVID NG D U1 LT3475EFE 20k CIN1 4.7uF 50V D1 C DATE E1 SHDN VIN E2 DESCRIPTION 0 R7 10k (Opt) R9 (Opt) E7 C3 0.1uF 6.3V R10 (Opt) GND RT GND 15 14 21 R11 (Opt) C5 (Opt) C6 (Opt) R12 24.3k 1% B E8 E9 LED1- LED1+ E6 GND C4 0.1uF 6.3V B E10 LED2+ E11 LED2- OPTIONAL EXTENDED DIMMING RANGE R13 1.0M (Opt) C7 A Q3 2N7002 (Opt) 220pF (Opt) 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 CIRUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. CONTRACT NO. APPROVALS DRAWN: TITLE: APPROVED: ENGINEER: KEITH S. DESIGNER: 4 3 SIZE SCHEMATIC Dual Step-Down 1.5A LED Driver DWG NO. A THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 5 TECHNOLOGY Rudy B CHECKED: 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 A Fax: (408)434-0507 LTC Confidential-For Customer Use Only 2 DATE: 2 REV SHEET 1 1 OF 1