REVISION HISTORY This circuit is proprietary to Linear Technology and supplied for use with Linear Technology parts. 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 Applications Engineering for assistance. ECO DATE 1 PROTO 08/15/07 APPROVED R14 R1 VIN OPT 20k CIN1 4.7uF 3 4 SW1 SW2 D4 R20 1k 1% 50V 1 PWM1 20 2 E9 B240A 1k 1% LED1 LED2 3 PWM2 R6 C3 OPT 0.1uF GND Q2 OPT Si2318DS VC2 12 R9 VC2 18 VC1 E6 UP TO 23V 1.5A E11 OPT R8 OPT LED2- R5 OPT R2 0 E10 REF VADJ2 100k 9 R4 VADJ1 22V E5 LED2+ 19 10k FMMT3904 11 REF 17 E8 Q1 OPT Si2318DS PWM2 OPT 13 LED1- PWM1 R18 10 REF UP TO 23V 1.5A LED1+ OUT2 GND E7 GND OUT1 D8 COUT2 2.2uF 50V B240A 2.2uF R17 7 D3 R19 COUT1 E4 16 25V L1 47uH 21 10k Q5 1 0.22uF GND 22V 8 C2 1N4448W 9.1V 0.22uF 25V L2 47uH 15 100k D6 D2 BOOST2 RT R16 C1 VC1 D7 1N4448W BOOST1 14 2 9.1V R15 6 D1 1 VC2 LT3475EFE-1 SHDN D5 VIN VIN 50V 3 MMBT3904 U1 5 VC1 Q4 2 UP TO 36V E3 GND DESCRIPTION E1 SHDN E2 * REV R3 0 C4 R7 0.1uF OPT R13 1.0M OPT C7 R12 24.3k 600kHz Q3 OPT *SEE QUICK START GUIDE 1% CONTRACT NO. 220pF OPT APPROVALS DRAWN MI DATE 08/14/07 CHECKED 2N7002 APPROVED OPTIONAL EXTENDED DIMMING RANGE TECHNOLOGY 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 Fax: (408)434-0507 TITLE SCH, LT3475EFE-1, DUAL STEP-DOWN 1.5A LED DRIVER ENGINEER DESIGNER SIZE CAGE CODE DWG NO REV 1 DC1315A Tuesday, January 22, 2008 SCALE: NONE FILENAME: 1315A-1.DSN SHEET 1 OF 1