DEMO MANUAL DC1160 LT3518: Full-Featured LED Driver with 2.3A Switch Current DESCRIPTION Demonstration circuit 1160 is a full-featured LED driver with 2.3A switch current featuring the LT®3518. The board is optimized to drive a 330mA LED string with a total LED voltage between the input voltage and 40V in a boost topology. The high input voltage range, high efficiency low side internal 2.3A NPN power switch, low voltage floating current sense amplifier, soft-start, high side PMOS PWM gate driver, high PWM dimming ratio, overvoltage protection, shutdown control pin, analog LED current dimming control, and externally programmable switching frequency (with sync) make the LT3518 an extremely versatile and powerful LED driving IC. The LT3518 has a 45V switch with 2.3A peak switch current limit rating. DC1160 has overvoltage protection at 40V if the LEDs are open or not properly attached to the terminals on the PCB. The shutdown function is activated by pulling the shutdown terminal to ground. In shutdown the boost configuration allows the input voltage to be seen on the output and if the attached LED array leaks current at the input voltage, the LEDs may not completely turn off. If the top gate is installed, it will provide shutdown output disconnect and the LEDs will turn off during shutdown. The CTRL terminal can be used to analog dim the LED current. In order to use the CTRL terminal, R6 (0Ω) pullup short resistor must be removed and replaced with a resistor divider from VREF to GND or an external voltage on the CTRL terminal. The high side PMOS PWM dimming MOSFET can be used to achieve 3000:1 PWM dimming ratio. The board is programmed for 1MHz oscillator frequency, but can be adjusted by changing R14. Higher frequency results in higher PWM dimming ratio. The VIN pin can be tied directly to PVIN for simplicity or powered from an additional low voltage input such as 3.3V for higher efficiency operation and lower on-chip power dissipation. A few simple modifications can be made to DC1160 in order to convert the board from a boost LED driver to a buck mode or buck-boost mode LED driver. Please consult the data sheet for schematic details and the factory for customization details. The LT3518 data sheet gives a complete description of the part, operation and applications information. The data sheet must be read in conjunction with this Quick Start Guide for demonstration circuit 1160. The LT3518 is assembled in a small 16-lead plastic (4mm × 4mm) QFN UF package with a thermally enhanced ground pad. Proper board layout is essential for maximum thermal performance. See the data sheet section Layout Considerations. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. dc1160f 1 DEMO MANUAL DC1160 QUICK START PROCEDURE DC1160 is easy to set up to evaluate the performance of the LT3518. Follow the procedure below: 5. Turn PVIN power on. Note: Make sure that the PVIN input voltage does not exceed 40V and that the VIN input voltage does not exceed 30V. 6. Turn VIN power on and observe the regulated LED current, the circuit efficiency, etc. without looking directly at the LEDs. 1. Connect a string of LEDs with forward voltage less than 40V, but greater than the PVIN input voltage, to the LED+ and GND terminals on the PCB as shown. 7. For PWM dimming, tie a 100Hz, 3V to 5V PWM waveform to the PWM terminal and GND and observe the PWM dimming LED current and PWM gate waveforms. 2. With power off, connect a 3.3V input power supply to the VIN and GND terminals on the PCB. 8. For shutdown, tie the SHDN terminal to GND and observe the LED current dropping to zero and the VIN input current dropping to about 65mA with R4 installed (VIN/51k). 3. With power off, connect a 3V to 40V input power supply to PVIN and GND terminals on the PCB. PVIN should not exceed the attached LED string voltage. PWM 5V/DIV 4. Connect a 3.3V source to PWM and GND. ILED 200mA/DIV 100 90 IL1 1A/DIV EFFICIENCY (%) 80 70 1μs/DIV 60 DC1160 F02 Figure 2. 3000:1 PWM Dimming at 100Hz, PVIN = 12V, VLED = 30V 50 40 30 20 VIN = 12V CTRL = VREF 0 20 60 80 40 PWM DUTY CYCLE (%) 100 DC1160 F01 Figure 1. DC1160A Efficiency 30V LED String, PVIN = VIN = 12V dc1160f 2 DEMO MANUAL DC1160 QUICK START PROCEDURE V 330mA LED ARRAY + VLED – – 6.5V TO 30V IPVIN + + A ILED – PVIN + V + A – – IVIN mA + + 3.3V + VIN 3.3V OR PWM V – DC1160 F03 OPTIONAL Figure 3. Proper Measurement Equipment Setup dc1160f 3 DEMO MANUAL DC1160 PARTS LIST ITEM QUANTITY REFERENCE PART DESCRIPTION MANUFACTURER, PART NUMBER REQUIRED CIRCUIT COMPONENTS: 1 1 C5 Capacitor, X7R, 4.7nF, 25V, 20% 0402 AVX, 04023C472MAT2A 2 2 C3,C4 Capacitor, X7R, 0.01μF, 16V, 10% 0402 AVX, 0402YC103KAT 3 1 CVIN Capacitor, X7R, 1μF, 50V, 10% 1206 Murata, GRM31MR71H105KA88L 4 2 CPVIN, COUT 5 1 D1 6 1 7 1 8 1 Capacitor, X5R, 2.2μF, 50V, 10% 1206 Murata, GRM31CR71H225KA88L Schottky Rectifier, 2.1A\60V, SMA Vishay, 10MQ060NPBF L1 Inductor, 10μH Sumida, CDRH8D28-100NC R1 Resistor, Chip, 0.300Ω, 1/4W, 1% 1206 Vishay, CRCW1206R300FNTA R8 Resistor, Chip, 392k, 1/16W, 1% 0402 Vishay, CRCW0402392KFKED 9 1 R12 Resistor, Chip, 10k, 1/16W, 1% 0402 Vishay, CRCW040210K0FKED 10 1 R13 Resistor, Chip, 5.1k, 1/16W, 1% 0402 Vishay, CRCW04025K10FKEA 11 1 R14 Resistor, Chip, 16.5k, 1/16W, 1% 0402 Vishay, CRCW040216K5FKEA 12 1 U1 I.C., LT3518EUF Linear Tech., LT3518EUF#PBF ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS: 1 0 C1,C2,C6 2 1 Q1 3 2 R6, R7 4 1 5 0 1 12 R4 OPT MOSFET, P-Channel 40-V (D-S) SOT23 Vishay, Si2319DS-T1-E3 Resistor, Chip, 0, 0402 Vishay, CRCW04020000Z0ED Resistor, Chip, 51k, 1/16W, 5% 0402 AAC, CR05-513JM R2, R3, R5, OPT R9-R11, R15, R16 HARDWARE FOR DEMO BOARD ONLY: E1 to E12 Testpoint, Turret, 0.094" Mill-Max, 2501-2 dc1160f 4 1 2 3 GND CTRL PWM SHDN GND A E10 E7 E8 E6 E5 VIN E3 3V-30V 40V Transients R10 Opt. R4 51k Opt. R16 1206 Opt. R6 0 R2 Opt. 1206 R5 Opt. OUT VIN B VREF CTRL TGEN C4 0.01uF 5 10 13 PWM SHDN U1 LT3518EUF 2 C5 4.7nF R13 5.1k R14 16.5k 1% 1MHz FB TG C 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. Customer Notice LTC CONFIDENTIAL - FOR CUSTOMER USE ONLY R7 0 C3 0.01uF R11 Opt. 9 4 CVIN 1uF 50V 10uH SS 8 4 CPVIN 2.2uF 50V GND 17 +C2 11 E4 R12 10k R8 392k OUT R1 0.300 1% 1206 E11 E9 E12 1 LED+ 330mA OUT GND SYNC GND Q2 Opt. R9 Opt. OUT R3 Opt. PVIN E2 Opt. +C1 E1 R15 Opt. LED+ LED+ PVIN Q1 Si2319DS 2 3 C6 2.2uF Opt. OUT E LINEAR TECHNOLOGY CORPORATION 12 16 COUT 2.2uF 50V D D Wednesday, July 18, 2007 Demo Circuit 1160A Document Number Sheet 1 E of LT3518EUF 1 Rev Full-Featured LED Driver with 2.3A Switch Current Date: Size A 1630 McCARTHY BLVD. MILPITAS, CA. 95035 PHONE (408) 432-1900 FAX (408) 434-0507 Title 1 D1 10MQ060N VC PVIN 3V-40V L1 6 CIN Boost 3 VIN 1 SW 2 SW 15 ISP RT PVIN C ISN B 1 14 SYNC 7 2 3 A 1 2 3 4 DEMO MANUAL DC1160 SCHEMATIC DIAGRAM dc1160f 5 DEMO MANUAL DC1160 ASSEMBLY DRAWINGS Silkscreen Top dc1160f 6 DEMO MANUAL DC1160 PCB LAYOUT AND FILM Silkscreen Top Component Side dc1160f 7 DEMO MANUAL DC1160 PCB LAYOUT AND FILM Inner Layer 2 Inner Layer 3 dc1160f 8 DEMO MANUAL DC1160 PCB LAYOUT AND FILM Soldermask Top Pastemask Top dc1160f 9 DEMO MANUAL DC1160 PCB LAYOUT AND FILM Soldermask Bottom Pastemask Bottom Solder Side dc1160f 10 DEMO MANUAL DC1160 FABRICATION DRAWING . . . dc1160f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 11 DEMO MANUAL DC1160 DEMONSTRATION BOARD IMPORTANT NOTICE Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations. If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other Intellectual property rights of any kind. LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and observe good laboratory practice standards. Common sense is encouraged. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer. Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation dc1160f 12 Linear Technology Corporation LT 0909 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2009