DEMO MANUAL DC1831A LT3763 High Power Constant Current, Constant Voltage Synchronous Buck Controller DESCRIPTION Demonstration circuit 1831A is a high power constant current, constant voltage synchronous buck controller featuring the LT®3763. The input of the demo board is up to 60V. The output is optimized for 10V, 10A as a LED driver. As an LED driver, the output current is being regulated until the output voltage reaches a programmed voltage limit. The voltage limit on the demo board is set to around 15V by R11 and R14. The load to be used with this demo board is high current LEDs or laser diodes. Smaller LEDs may not be able to handle the high current, even for a short period of time. It is necessary to mount the LED load on a proper heat sink. A fan may become necessary to avoid exceeding LED’s maximum temperature rating. The demo circuit 1831A achieves fast current rise time from 0A to 10A. To see the real rise time, connecting wires between the LED and the board should be as short as possible to minimize the wire inductance and resistance. The cathode of the LED should return to LED– with R17 populated with a resistor in a few mΩ. It is recommended to measure the voltage on R17 with a short 50Ω coax cable directly into a BNC connector on the oscilloscope. The current can be calculated from the measured voltage. A current probe adds more delays to the rise time so using a current probe is not recommended. If fast rise time is not required, the cathode of the LED can be connected to GND as shown in Figure 2. The input voltage range of the LT3763 itself is 6V to 60V. The demo board input range is 12V to 60V, therefore, the demo board utilizes 80V MOSFETs. If an application has a maximum input voltage of 48V, 60V MOSFETs such as BSC100N06LS3, can be used for better efficiency at lower voltage range. The typical efficiency of the demo board is 95% from a 24V input to a 10V, 10A load. The lower the input voltage, the higher the efficiency tends to be for a given load. At an output power level of 100W, even a one percent efficiency improvement is a big advantage in minimizing temperature rise. If an efficiency measurement is needed in an application, the output voltage must be measured at the output capacitors instead of at the LED load. This prevents cable loss from being counted as a loss of the board. The LT3763 turns off unnecessary circuits during PWM off period to minimize power losses. As a result, efficiency in many PWM dimming applications is high. The LT3763 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 1831A. 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. 100 99 EFFICIENCY (%) 98 97 96 LED CURRENT = 5A 95 94 LED CURRENT = 10A 93 92 In most applications, input voltage reaching the maximum specification is a transient event. However, a fan helps the circuit to stay cool if running at or near peak input voltage at full load in steady state. If running in steady state at or near maximum input voltage and full load is required, please contact LTC applications engineering. 91 90 10 20 30 40 VIN (V) 50 60 DN1831A F01 Figure 1. Demo Board Efficiency dc1831af 1 DEMO MANUAL DC1831A PERFORMANCE SUMMARY SYMBOL PARAMETER VIN Input Supply Range (TA = 25°C) CONDITIONS MIN TYP 12 MAX 60 15 UNITS V VOUT Maximum Output Voltage IOUT Output Current 9.4 10 10.6 A fSW Switching Frequency 380 430 480 kHz EFF Efficiency at DC IOUT = 10A, VOUT = 10V 95 V % QUICK START PROCEDURE Demonstration circuit 1831A is easy to set up to evaluate the performance of the LT3763. 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. Note: make sure VIN is below 60V. 3. When measuring input and output voltage, measure at test points TP1 to TP4. 4. Turn on the power at the input. 5. Carefully evaluate other design parameters as needed. 2. With power off, connect the LED load to VOUT and GND (without PWM dimming) or VOUT and LED– (with PWM dimming). dc1831af 2 DEMO MANUAL DC1831A QUICK START PROCEDURE Figure 2. Proper Measurement Equipment Setup dc1831af 3 DEMO MANUAL DC1831A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 C1 Cap., Alum, 33μF,100V, 10.3x10.3 Sun Elect., 100CE33FS 2 2 C2, C5 Cap., X7R, 2.2μF, 100V, 10%, 1210 Murata, GRM32ER72A225KE35L 3 1 C6 Cap., X7R, 1μF, 100V, 10%, 1206 Murata, GRM31CR72A105KA01L 4 1 C7 Cap., X7R, 0.22μF, 10V, 10%, 0603 Murata, GRM188R71A224KA01D 5 2 C8, C10 Cap., POSCAP, 68μF, 16V Sanyo, 16TQC68MYF 6 2 C9, C11 Cap., X7R , 22μF, 25V, 10%, 1210 Murata, GRM32ER71E226KE15L 7 1 C12 Cap., X5R, 22μF, 6.3V,10%, 0805 Murata, GRM21BR60J226ME39L 8 1 C13 Cap., C0G, 2nF, 50V, 5%, 0603 Murata, GRM1885C1H202JA01D 9 2 C14, C19 Cap., X7R, 1000pF, 50V, 10%, 0603 AVX, 06035C102KAT2A 10 1 C15 Cap., X7R, 10nF,16V, 0603 Murata, GRM188R71C103KA01D 11 1 C17 Cap., X7R, 5.1nF, 10%, 25V, 0603 Murata, GRM188R71E512KA01 12 1 D1 1.0A Schottky Diode, DFLS160 Diodes/Zetex, DFLS160-7 13 1 D2 2.0A Schottky Diode, DFLS260 Diodes/Zetex, DFLS260-7 14 1 L1 Inductor, 2.8μH WE., 7443551280 15 4 Q1, Q2, Q3, Q4 MOSFET Renesas, RJK0851DPB 16 1 Q5 MOSFET Infineon, BSC014N03LS G 17 1 R1 Res., Chip, 374k, 1%, 0603 Vishay, CRCW0603374KFKEA 18 1 R2 Res., Chip, 124k, 1%, 0603 Vishay, CRCW0603124KFKEA 19 6 R3, R5, R8, R24, R25, R27 Res., Chip, 100k, 1%, 0603 Vishay, CRCW0603100KFKEA 20 1 R4 Res., Chip, 0.005Ω, 1W, 1%, 2512 Vishay, WSL25125L000FEA 21 1 R7 Res., Chip, 45.3k, 1%, 0603 Vishay, CRCW060345K3FKEA 22 1 R11 Res., Chip, 5.62k, 1%, 0603 Vishay, CRCW06035K62FKEA 23 1 R12 Res., Chip, 680K, 1%, 0603 Vishay, CRCW0603680KFKEA 24 1 R14 Res., Chip, 487Ω, 1%, 0603 Vishay, CRCW0603487RFKEA 25 1 R15 Res., Chip, 30.9k, 1%, 0603 Vishay, CRCW060330K9FKEA 26 1 U1 I.C. LT3763EFE, 20-Pin TSSOP Linear Tech., LT3763EFE Additional Demo Board Circuit Components 1 0 C3, C4 Cap., 1210, Opt 2 0 C16, C18, C20 Cap., 0603, Opt 3 2 R6, R17 Res., Chip, 0Ω, 2512 4 0 R9, R20, R21 Res., 1206, Opt 5 8 R10, R13, R16, R18, R19, R22, Res., Chip, 0Ω, 0603 R23, R26 Vishay, CRCW25120000Z0EG Vishay, CRCW06030000Z0ED Hardware–For Demo Board Only 1 5 J1, J2, J3, J4, J5 Jack, Banana Keystone, 575-4 2 10 E1-E8, E10, E11 Testpoint, Turret, 0.094" Mill-Max, 2501-2-00-80-00-00-07-0 3 4 Stand-Off, Nylon 0.5" tall Keystone, 8833 (Snap On) dc1831af 4 DEMO MANUAL DC1831A SCHEMATIC DIAGRAM dc1831af 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. 5 DEMO MANUAL DC1831A 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 dc1831af 6 Linear Technology Corporation LT 1012 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2012