3 *** SEE QUICK START GUIDE R21 C1 4.7uF 25V TP12 GND TP13 VIN 2.8V-16V TP1 36V Transient SHDN 11 TP4 R2 0 R3 93.1k GND CTRL2 TP7 4 VIN VS 5 L 1 2 SW SW OUT SHDN OUT TP2 C2 4.7uF 50V C21 4.7uF 50V GND TP11 6 R11 VREF CTRL1 3 LED- OUT PDS560 C20 opt. * U1 TP8 D1 L1 10uH CIN 1uF 25V R1 100k 2 R4 36.5k 10 * VREF 13 CTRL2 12 CTRL1 EXPOSED PAD PWM SS VC 14 16 9 TP10 C3 1uF TP6 C5 opt. OVPSET 8 GND RT PAD1 15 R9 TP5 VREF LED+ 40V max 350mA OPTIONAL CIRCUIT 24k 17 R10 100k ** C4 0.1uF OUT Vs R12 opt. R6 31.6k 1% 1 MHz D3 opt. Q3 opt. B U2 LT3003EMSE(OPT.) ** LED1 ** LED2 ** LED3 OUT E R8 opt. R5 opt. LED 7 LED1 VEE 2 10 LED2 SHDN 9 3 LED3 OT2 8 4 VMAX OT1 7 5 VIN PWM 6 C7 opt. D2 opt. PWM 15V max 1 GND SHDN TP3 3 R22 opt. R7 10k SHDN PAD1 ** PAD2 ** R14 opt. 11 GND C6 3.3uF 25V R20 opt. C *** Q2 opt. 1 VS 2.8V-25V 36VDC MAX PWM 1 opt. 2 Vs Q1 Si2318DS PWM PWM TP9 LED1-LED3, PAD1, AND PAD2 ARE LANDING PADS IN LAYOUT. ** NOTE: PAD1 LOCATED NEXT TO Vc. * VERSION TABLE ASSEMBLY VERSION U1 R11 DC949A-A LT3478EFE-1 DO NOT STUFF DC949A-B LT3478EFE 0.1 ohm 1% 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 TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. CONTRACT NO. APPROVALS DRAWN June Wu DATE 1/9/07 CHECKED TECHNOLOGY TITLE LT3478EFE-1/LT3478EFE 4.5A Boost LED Driver with PWM APPROVED ENGINEER Keith Szolusha 1/9/07 DESIGNER Monday, January 15, 2007 SIZE 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 Fax: (408)434-0507 CAGE CODE SCALE: FILENAME: DWG NO REV A DC949A SHEET 1 OF 1