DEMO MANUAL DC1725A LT3759 Wide Input Voltage Range Boost/SEPIC/Inverting Controller DESCRIPTION The LT3759 is a current mode DC/DC controller operating over an input range of 1.6V to 42V, making it well suited for applications ranging from single-cell lithium-ion battery portable electronics to high voltage automotive and industrial power supplies. It also exhibits low shutdown quiescent current of 1μA, making it an ideal fit for battery operated systems. Thanks to a novel FBX pin architecture, the LT3759 can be connected directly to a divider from either a positive or negative output feedback voltage to ground. It also packs many popular features such as softstart, input undervoltage lockout, adjustable frequency and synchronization in a small 12-lead exposed pad MSOP package. Demonstration circuit 1725A features LT3759 in a 485kHz boost converter, designed for a 5V/2A output from a 1.8V to 4.5V input. The demo circuit configures the shutdown voltage at typical 1.70V, which means that the input voltage can be dropped to as low as 1.70V, once it starts up. The start-up voltage is set at 2.5V but can be adjusted by changing R1 and R2 values. The LT3759 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. 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. PERFORMANCE SUMMARY (TA = 25°C) PARAMETER CONDITIONS MIN Input Voltage Range, VIN IOUT = 0mA~2A 1.8 TYP Minimum Start-up Voltage MAX UNITS 4.5 V 2.5 V Switching Frequency IOUT = 2A 485 Output Voltage, VOUT VIN = 1.8V~4.5V IOUT = 0mA~2A 4.85 Maximum Continuous Output Current, IOUT VIN = 1.8V~4.5V 2.0 Output Voltage Ripple VIN = 2.5V, IOUT = 2A 60 mV Typical Efficiency VIN = 4.5V, IOUT = 2A 90 % 5.0 kHz 5.15 V A dc1725af 1 DEMO MANUAL DC1725A QUICK START PROCEDURE Demo circuit 1725A is easy to set up to evaluate the performance of LT3759. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below. NOTE: Make sure that the input voltage does not exceed 4.5V. If higher operating voltage is required, power components with higher voltage ratings should be used. 1. With power off, connect the input power supply, load and meters as shown in Figure 1. Preset the load to 0A, and VIN supply to be 0V. Place jumpers in the following positions for a typical 5V application: 3. Once the proper output voltage is established, adjust the input voltage and load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Typical efficiency curve is shown in Figure 3. EN (JP1) ON SYNC (JP2) OFF 2. Turn on VIN and increase slowly to 2.5V. Check for proper output voltages. The output should be regulated at 5V (±3%). The switching frequency should be about 485kHz. NOTE: If there is no output, or the output is out of spec, temporarily disconnect the load to make sure that the load is not set too high, and the power supply current capability is above 7A. Minimize voltage drop over the input wires. NOTE: When measuring the input or output voltage ripples, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the VIN and GND, or VOUT and GND terminals. See Figure 2 for proper scope probe technique. dc1725af 2 DEMO MANUAL DC1725A QUICK START PROCEDURE dc1725a F01 Figure 1. Proper Measurement Equipment Setup 100 90 EFFICIENCY (%) 80 70 60 50 40 30 20 VIN = 1.8V VIN = 2.5V VIN = 4.5V 10 0 0 INPUT OR OUTPUT CAPACITOR dc1725a F01 200 400 600 800 1200 1600 2000 1000 1400 1800 LOAD CURRENT (mA) dc1725a F03 Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple Figure 3. Efficiency with Different Input Voltages dc1725af 3 DEMO MANUAL DC1725A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 4 CO1, CIN1, CO2, CIN2 CAP, 1210, 100μF, 20%, 6.3V, X5R MURATA GRM32ER60J107ME20L 2 1 CIN3 CAP, 270μF, 20%, 10V SANYO 10SVPC270M 3 1 C1 CAP, 1206, 4.7μF, 10%, 50V, X5R TAIYO YUDEN UMK316BJ475KL 4 1 C2 CAP, 0402, 0.1μF, 10%, 16V, X5R AVX 0402YD104KAT2A 5 1 C3 CAP, 0402, 22nF, 10%, 25V, X7R MURATA GRM155R71E223KA61D 6 1 C4 CAP, 0402, 120pF, 10% 25V, X7R AVX 04023C121KAT2A 7 1 D1 DIODE, SCHOTTKY BARRIER RECTIFIER SMA DIODES INC/ZETEX SBR3U20SA 8 1 L1 IND, 2.2μH WÜRTH ELEKTRONIK 7443552200 9 1 Q1 XSTR, N-CHANNEL MOSFET VISHAY Si7858ADP-T1-E3 10 1 RCS1 RES, 0815 0.005Ω, 1% 1W SUSUMU/THIN FILM RL3720WT-R005-F 11 1 RFBA RES, 0402, 34kΩ, 1%, 1/16W VISHAY CRCW040234K0FKED 12 1 RFBB RES, 0402, 15.8kΩ, 1%, 1/16W VISHAY CRCW040215K8FKED 13 1 R1 RES, 0402, 348kΩ, 1%, 1/16W VISHAY CRCW0402348KFKED 14 1 R2 RES, 0402, 887kΩ, 1%, 1/16W VISHAY CRCW0402887KFKED 15 1 R3 RES, 0402, 5.1kΩ, 1%, 1/16W VISHAY CRCW04025K10FKED 16 1 R4 RES, 0402, 16.9kΩ, 1%, 1/16W VISHAY CRCW040216K9FKED 17 1 R5 RES, 0402, 100kΩ, 1%, 1/16W VISHAY CRCW0402100KFKED 18 1 U1 IC, INVERTING CONVERTER LINEAR TECH. LT3759EMSE Hardware/Components (For Demo Board Only) 1 7 E1-E7 TURRETS MILLMAX 2501-2-00-80-00-00-07-0 2 2 JP1, JP2 HEADER, 3-PIN, 2mm SAMTEC TMM-103-02-L-S 3 2 J1, J2 JACK, BANANA KEYSTONE 575-4 4 2 JP1, JP2 SHUNT, 2mm SAMTEC 2SN-BK-G 5 4 MH1, MH2, MH3, MH4 STANDOFF, SNAP ON KEYSTONE 8834 6 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 1725A 7 1 STENCIL FOR BOTH SIDES STENCIL 1725A dc1725af 4 DEMO MANUAL DC1725A SCHEMATIC DIAGRAM dc1725af 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 DC1725A 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 dc1725af 6 Linear Technology Corporation LT 1011 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2011