DEMO MANUAL DC1497A LT3597 60V Triple Step-Down LED Driver Description Demonstration circuit 1497A is a 60V triple step-down LED driver featuring the LT3597. The demo board is optimized for 9 white LEDs, 100mA output per regulator from a 48V input. When different number or different color of LEDs is used for evaluation, attentions should be given to the maximum output voltage setting and fault reporting. The connections between the board and LEDs strings should be as short as feasible. The circuit achieves 10,000:1 PWM dimming at 100Hz PWM frequency. LED dimming can also be done by analog control of the CTRL1-3 pin. If dimming is not required, leave the PWM1-3 and CTRL1-3 terminals unconnected. The demo circuit pulls PWM1-3 and CTRL1-3 pins up to VREF. The switching frequency is set to 1MHz on the demo circuit for best solution size. The LT3597 internal compensation makes it a lot easier for a designer to design different application circuits. The LT3597 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this quick start guide for demo circuit 1497A. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, µModule, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. PWM 2V/DIV ILED 50mA/DIV 200ns/DIV DC1497a Figure 1. PWM Dimming dc1497af 1 DEMO MANUAL DC1497A PERFORMANCE SUMMARY (TA = 25°C) SYMBOL PARAMETER CONDITIONS MIN VIN* Input Supply 6 VLED LED String Voltage 28 VOUT(MAX) Maximum Output Voltage IOUT Output Current R23 = R24 = R25 = 20k DIM PWM Dimming Ratio PWM Dimming Frquency = 100Hz FSW Switching Frequency R22 = 33.2k EFE Efficiency VIN = 48V, VOUT = 29V, IOUT = 100mA, BIAS = 5V, No Dimming TYP MAX 55 34 38 98 100 UNITS V V V 102 mA 1.1 MHz 10,000:1 0.9 1 87 % *Actual VIN range should be determined by the load. For 9 white LEDs per channel, use a 48V input for evaluation. dc1497af 2 DEMO MANUAL DC1497A quick start procedure Demonstration circuit 1497A is easy to set up to evaluate the performance of the LT3597. Refer to Figure 2 for proper measurement equipment setup and follow the procedure below: 1.With power off, connect the input power supply to VIN and GND. 2.With power off, connect a 5V bias supply to BIAS and GND. Bias voltage should be less then 25V. 3. With power off, connect 3 LED strings, 9 white LEDs per string, between LED1+ and LED1–, LED2+ and LED2–, LED3+ and LED3– respectively. 4.Turn on the power at the input. Be careful not to look at the LEDs directly. 5.Carefully evaluate all design parameters as needed. 6.To evaluate PWM dimming, apply a PWM signal to PWM1, PWM2 and/or PWM3. To evaluate 10,000:1 PWM dimming, the PWM signal should have a frequency of 100Hz and the minimum pulse width can be as low as 1µs. 7. To modify the demo board for other applications, please contact the Linear Applications Group for help. Figure 2. Demo Board Setup dc1497af 3 DEMO MANUAL DC1497A parts list ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 3 C1, C2, C3 Capacitor, X7R, 4.7µF, 50V, 10%,1206 Murata, GRM31CR71H475KA12L 2 3 C4, C5, C6 Capacitor, X7R, 0.22µF, 25V, 10%, 0603 Murata, GRM188R71E224KA88L 3 2 C7, C10 Capacitor, X7R, 2.2µF, 100V, 10%, 1210 Murata, GRM32ER72A225KA35L 4 1 C8 Capacitor, X5R, 4.7µF, 25V, 10%, 0805 Taiyo Yuden, TMK212BJ475KG-T 5 3 D1, D2, D3 Diode, Schottky, Power DI-123 Diodes/Zetex, DFLS160-7 6 3 L1, L2, L3 Inductor, 100µH Sumida, CDR6D28MNNP-101NC 7 3 R1, R2, R3 Resistor, Chip, 93.1k, 1/16W, 1%, 0402 Vishay, CRCW040293K1FKED 8 3 R4, R5, R6 Resistor, Chip, 3.01kΩ, 1/16W, 1%, 0402 Vishay, CRCW04023K01FKED 9 1 R16 Resistor, Chip, 82.5kΩ, 1/16W, 1%, 0402 Vishay, CRCW040282K5FKED 10 1 R19 Resistor, Chip, 49.9kΩ, 1/16W, 1%, 0402 Vishay, CRCW040249K9FKED 11 1 R20 Resistor, Chip,10kΩ, 1/16W, 1%, 0402 Vishay, CRCW040210K0FKED 12 1 R22 Resistor, Chip, 33.2kΩ, 1/16W,1%, 0402 Vishay, CRCW040233K2FKED 13 3 R23, R24, R25 Resistor, Chip, 20kΩ, 1/16W, 1%, 0402 Vishay, CRCW040220K0FKED 14 1 U1 I.C. LT3597EUHG, 52-Pin QFN-5mm × 8mm Linear Technology, LT3597EUHG Capacitor, Aluminum 4.7µF, 63V Sun Electric, 63CE4R7BS Additional Demo Board Circuit Components 1 1 C9 2 0 D4 Diode, OPT, SOD-323 3 1 R7 Resistor, Chip, 270kΩ, 1/16W, 1%, 0603 Vishay, CRCW0603270KFKEA 4 1 R9 Resistor, Chip, 91kΩ, 1/16W, 1%, 0402 Vishay, CRCW040291K0FKED 5 7 R10-R14, R17, R18 Resistor, Chip, 100kΩ,1/16W,1%, 0402 Vishay, CRCW0402100KFKED 6 1 R15 Resistor, Chip, 8.87kΩ,1/16W, 1%, 0402 Vishay, CRCW04028K87FKED 7 1 R21 Thermistor, Chip, 100k,1%, 0603 Murata, NCP18WF104F12RB Turret, Testpoint, 091" Mill Max 2501-2-00-80-00-00-07-0 Hardware – For Demo Board Only 1 8 E1-E5, E12-E14 2 10 E6-E11, E15-E18 Turret, Testpoint, 063" Mill Max 2308-2-00-80-00-00-07-0 3 1 JP1 Jumper, 3-Pin 1 Row .079CC Samtec, TMM-103-02-L-S 4 1 SHUNT FOR PJ1 Shunt, .079" Center Samtec, 2SN-BK-G 5 4 Stand-Off, Nylon 0.5" Tall Keystone, 8833 (Snap On) dc1497af 4 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. A B C D FAULT BIAS TP SYNC CTRL3 CTRL2 CTRL1 PWM3 PWM2 PWM1 GND VIN 6V - 55V E15 E17 E19 5 + R20 10K E18 E11 E10 E9 E8 E7 E6 E5 E4 OPT D4 R22 33.2K C9 4.7uF 63V R24 20K R25 20K R17 100K R14 100K C10 2.2uF 100V 1210 53 16 15 14 17 27 31 32 33 26 GND ISET3 ISET2 ISET1 RT SYNC CTRL3 CTRL2 CTRL1 NC R13 R12 100K 100K R10 100K C8 4.7uF 25V 0805 4 1. ALL RESISTORS ARE 0402 NOTE: UNLESS OTHERWISE SPECIFIED R23 20K R18 100K VREF C7 2.2uF 100V 1210 R11 100K VREF 30 VIN 4 29 PWM2 28 PWM3 GND 18 BIAS 37 FAULT 25 R7 270K 0603 R19 49.9K R16 82.5K LED3 VOUT3 FB3 DA3 SW3 BST3 LED2 VOUT2 FB2 DA2 SW2 BST2 LED1 2 24 23 35 43 41 3 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. SCALE = NONE 2 WALKER B. AK APPROVALS 1 DATE: SIZE R6 3.01K 50V C3 C2 50V R5 3.01K DESCRIPTION E14 E3 E13 E2 LED3- LED3+ LED2- LED2+ LED1- LED1+ OFF ON EN/UVLO Wednesday, February 02, 2011 1 DEMO CIRCUIT 1497A LT3597EUHG SHEET TRIPLE STEP-DOWN LED DRIVER IC NO. DATE 01-26-11 1 OF 1 2 REV. 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only R3 93.1K 4.7uF 1206 E1 JP1 3 2 1 E12 LED2+ APPROVED WALKER B. EN/UVLO E16 LED1+ LED3+ R2 93.1K 4.7uF 1206 R1 93.1K 4.7uF 1206 TECHNOLOGY L3 100uH C1 50V 1 REVISION HISTORY 2ND PROTOTYPE R4 3.01K L2 100uH L1 100uH 1 REV TITLE: SCHEMATIC D3 DFLS160 2 C6 0.22uF 0603 D2 DFLS160 39 1 C5 0.22uF 0603 1 __ ECO D1 DFLS160 2 C4 0.22uF 0603 2 2 21 22 34 44 46 48 20 19 7 6 4 CUSTOMER NOTICE t FB1 DA1 SW1 BST1 R9 91K VOUT1 3 LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APP ENG. APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. R15 8.87K R21 100K 0603 VREF U1 LT3597EUHG PWM1 TSET 11 51 VIN 50 VIN VREF 12 9 EN/UVLO CTRLM 13 5 A B C D DEMO MANUAL DC1497A Schematic Diagram dc1497af 5 DEMO MANUAL DC1497A 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 dc1497af 6 Linear Technology Corporation LT 0411 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2011