5 4 3 2 1 REVISION HISTORY ECO REV 1 3 VIN DESCRIPTION PRODUCTION APPROVED DATE WALKER B. 10-02-09 * R17 0 D D PVIN 4 E1 3 VREF 4 CTRL_T 6 CTRL_H 7 CTRL_L R19 432K R20 100K R21 OPT C7 2nF R4 100K R22 OPT CTRL_H E4 CTRL_L E5 18 PWM E6 17 CTRL_SEL E7 16 SYNC E8 SW 1 2 3 C18 470uF CTRL_SEL SYNC SS PWMGH 19 PWMGL 22 15 RT VCH 14 VCL 13 10 GND GND GND 29 21 GND FB 8 1 B C19 OPT C5 470uF C6 470uF C13 OPT C14 OPT + 2 D2 DFLS240 8 7 5 6 4 2 C27 10uF C21 470uF R15 10 R16 10 C LEDE11 8 7 5 6 4 Q5 IS+ E13 Q6 R25 Si7234DP OPT IS- R23 3.01K C23 470uF + + C22 OPT R7 51K R8 51K + C20 OPT Si7234DP C15 33nF C8 1uF R14 100K (400kHz) + SENSE+ 11 20 R13 100K + VCC_INT GND R12 100K VOUT* 24 Q3 RJK0330DPB Q4 OPT 4 LG 26 9 R11 OPT 0.0025 E10 PWM GND R10 100K R3 C4 22uF 6.3V SENSE- 12 R9 100K L1 1.3uH 3 R18 24.9K VCC_INT 3 E2 GND 1 EN/UVLO 6V - 36V E12 1 2 C11 100uf,50V 50CE100LX C3 0.22uF D1 PMEG4002EB VCC_INT 27 4.7uF 1 2 3 EN/UVLO VIN E9 + 4.7uF 5 6 7 8 LT3743EUFD 28 C 2 U1 C2 1uF 50V CBOOT 25 R2 374K 23 R1 124K HG E3 5 GND RJK0305DPB R26 OPT R27 0 C1 C12 C16 C17 Q2 * 6V - 36V Q1 1 VIN 5 6 7 8 VIN * C25 470uF C24 OPT E14 R24 2K C9 5.6nF B R5 51K C10 5.6nF C26 R6 10k 1.2nF * See Quick Start Guide CUSTOMER NOTICE A CONTRACT NO. 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. APPROVALS ENG. 4 3 WALKER B. TITLE: SCHEMATIC HIGH CURRENT SYNCHRONOUS STEP-DOWN LED DRIVER WITH THREE-STATE CONTROL SIZE A THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 5 TECHNOLOGY PCB DES. ANTONINA K. DATE: 2 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 Fax: (408)434-0507 LTC Confidential-For Customer Use Only IC NO. REV LT3743EUFD 3 DEMO CIRCUIT 1470A Friday, December 04, 2009 SHEET 1 1 OF 1 A