DEMO MANUAL DC1781A LT3507A Triple Monolithic Step-Down Regulator with LDO DESCRIPTION Demo circuit 1781A is a Triple Monolithic Step-Down Regulator with LDO featuring the LT3507A. The demo circuit is designed for 1.8V, 3.3V, 5.0V and 2.5V outputs from a 7V to 36V input. The current capability of each channel is 2.7A, 1.5A, 1.8A and 0.3A respectively. Independent input voltage, feedback, soft-start and power good pins for each channel simplify complex power supply tracking/ sequencing requirements. All three converters are either synchronized to a common external clock input or single-resistor programmable from 250kHz to 2.5MHz using internal oscillator. At all frequencies, a 180° phase shift between VOUT1 and the other two outputs is maintained, reducing input voltage ripple and PERFORMANCE SUMMARY PARAMETER component size. Programmable frequency allows for optimization between efficiency and external component size. Each output can be independently disabled using its own soft-start pin, or by using the SD terminal the entire part can be placed in a low quiescent current shutdown mode. The LT3507A 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 1781A. 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. (TA = 25°C) CONDITIONS Minimum Input Voltage VALUE 7V Maximum Input Voltage 36V Output Voltage VOUT1 VIN = 7~36V 1.80V ±3% Output Voltage VOUT2 VIN = 7~36V 3.33V ±3% Output Voltage VOUT3 VIN = 7~36V 5.0V ±3% Output Voltage VOUT4 VIN = 7~36V 2.52V ±3% Switching Frequency 450kHz ±10% Maximum Output Current IOUT1 VIN = 7~36V 2.7A Maximum Output Current IOUT2 VIN = 7~36V 1.5A Maximum Output Current IOUT3 VIN = 7~36V 1.8A Maximum Output Current IOUT4 VIN = 7~36V 0.3A Voltage Ripple VOUT1 VIN = 12V, IOUT1 = 2.7A <20mV Voltage Ripple VOUT2 VIN = 12V, IOUT2 = 1.5A <20mV Voltage Ripple VOUT3 VIN = 12V, IOUT3 = 1.8A <20mV Voltage Ripple VOUT4 VIN = 12V, IOUT4 = 0.3A <10mV dc1781af 1 DEMO MANUAL DC1781A QUICK START PROCEDURE Demo circuit 1781A is easy to set up to evaluate the performance of the LT3507A. Refer to Figure 2 for proper measurement equipment setup and follow the procedure below: NOTE. When measuring the input or output voltage ripple, 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 or VOUT and GND terminals. See Figure 3 for proper scope probe technique. 1. With power off, connect the input power supply to VIN and GND. 2. Turn on the power at the input. NOTE. Make sure that the input voltage does not exceed 36V. 3. Check for the proper output voltages. NOTE. If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 4. Once the proper output voltages are established, adjust the load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. 100 90 EFFICIENCY (%) 80 70 60 50 40 30 20 VOUT1 = 1.8V VOUT1 = 3.3V VOUT1 = 5.0V 10 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 LOAD CURRENT (A) 2.4 2.7 DC1781A F01 Figure 1. DC1781A Buck Channel Efficiency at VIN = 12V, f = 450kHz dc1781af 2 DEMO MANUAL DC1781A QUICK START PROCEDURE Figure 2. DC1781A Proper Equipment Setup GND VIN Figure 3. Measuring Input or Output Ripple dc1781af 3 DEMO MANUAL DC1781A QUICK START PROCEDURE SYNC FUNCTION EMI FILTER Install a 10k R20 resistor if the board is synchronized from an external signal generator. Install EMI filters on the backside of the DC1781A, however, a trace cut is required for the insertion of the option circuit. See Figure 4 for the cut line. Figure 4. Cut Line for the EMI Filter Installation dc1781af 4 DEMO MANUAL DC1781A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 3 CIN1, CIN2, CIN3 CAP., X7R, 2.2μF, 50V, 10%, 1210 TDK, C3225X7R1H225K 2 1 C1 CAP., X7R, 0.47μF, 25V, 10%, 0603 MURATA, GRM188R71E474KA12D 3 2 C2, C9 CAP., X7R, 0.22μF, 25V, 10%, 0603 TDK, C1608X7R1E224K 4 2 C3, C10 CAP., X5R, 47μF, 10V, 20%, 1206 TAIYO YUDEN, LMK316BJ476ML-T 5 1 C4 CAP., X5R, 22μF, 6.3V, 20%, 1206 TAIYO YUDEN, JMK316BJ226ML 6 3 C5, C6, C11 CAP., X7R, 680pF, 50V, 10%, 0402 AVX, 04025C681KAT 7 4 C7, C8, C13, C20 CAP., X5R, 0.1μF, 10V, 10%, 0402 AVX, 0402ZD104KAT 8 1 C12 CAP., X5R, 2.2μF, 6.3V, 20%, 0603 TAIYO YUDEN, JMK107BJ225MA 9 3 C15, C17, C19 CAP., NPO, 47pF, 50V, 5%, 0402 AVX, 04025A470JAT 10 1 D4 DIODE, SCHOTTKY, B340A, SMA-DIODE DIODES INC., B340A 11 2 D5, D6 DIODE, SCHOTTKY, B240A, SMA-DIODE DIODES INC., B240A 12 3 D7, D8, D9 DIODE, SCHOTTKY, CMDSH-4E, SOD323 CENTRAL SEMI., CMDSH-4E 13 1 L1 IND., 4.7μH NIC, NPIM74C4R7MTRF 14 1 L2 IND., 8.2μH NIC, NPIM74C8R2MTRF 15 1 L3 IND., 10μH NIC, NPIM74C100MTRF 16 1 Q1 XTOR, NPN, 50V LOW SATURATION, MLP322 ZETEX, ZXTCM322TA 17 5 R1, R2, R3, R15, R22 RES., CHIP, 100k, 1/16W, 1%, 0402 YAGEO, RC0402FR-07100KL 18 1 R4 RES., CHIP, 12.4k, 1/16W, 1%, 0402 VISHAY, CRCW040212K4FKEA 19 1 R5 RES., CHIP, 31.6k, 1/16W, 1% 0402 VISHAY, CRCW040231K6FKEA 20 3 R6, R7, R11 RES., CHIP, 20k, 1/16W, 1% 0402 VISHAY, CRCW040220K0FKEA 21 3 R8, R9, R23 RES., CHIP, 10k, 1/16W, 1% 0402 YAGEO, RC0402FR-0710KL 22 1 R10 RES., CHIP, 53.6k, 1/16W, 1% 0402 VISHAY, CRCW040253K6FKEA 23 1 R12 RES., CHIP, 10.2k, 1/16W, 1% 0402 NIC, NRC04F1022TRF 24 1 R13 RES., CHIP, 1.07k, 1/16W, 1% 0402 YAGEO, RC0402FR-071K07L 25 1 R14 RES., CHIP, 49.9k, 1/16W, 1% 0402 VISHAY, CRCW040249K9FKEA 26 1 R16 RES., CHIP, 499, 1/16W, 1% 0402 AAC, CR05-4990FM 27 1 R17 RES., CHIP, 18.2k, 1/16W, 1% 0402 VISHAY, CRCW040218K2FKEA 28 1 R18 RES., CHIP, 3.32k, 1/16W, 1% 0402 VISHAY, CRCW04023K32FKEA 29 1 R19 RES., CHIP, 107k, 1/16W, 1% 0402 AAC, CR05-1073FM 30 1 U1 I.C., LT3507EUHF, QFN38UHF LINEAR TECH., LT3507EUHF dc1781af 5 DEMO MANUAL DC1781A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Additional Demo Board Circuit Components 1 1 CIN4 CAP., ELECTROLYTIC, 22μF, 50V SANYO, 50CE22LX 2 0 C14, C16, C18, C28 CAP., 0402 OPT 3 0 C21 CAP., X7R, 0.01μF, 50V, 10%, 0603 OPT 4 0 C22 CAP., X7R, 2.2μF, 50V, 10%, 1210 OPT 5 0 C23 CAP., ELECTROLYTIC, 22μF 50V OPT 6 4 C24-C27 CAP., X5R, 1μF, 10V, 10%, 0603 MURATA, GRM188R61A105K 7 0 C29 CAP., 1206 OPT 8 0 D1, D2, D3 DIODE, SCHOTTKY, CMDSH-4E, SOD323 OPT 9 0 FB1 BEAD, 1206 OPT TAIYO YUDEN, FB MJ3216HS800 10 0 L4 IND., 22μH, OPT 11 0 R20 RES., CHIP, 0402 OPT 12 0 R21 RES., CHIP, 0603 OPT VISHAY, IHLP4040DZER220-M01 Hardware-For Demo Board Only: 1 10 E1, E2, E6-E9, E12-E15 TP, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0 2 9 E3, E4, E5, E10, E11, E16-E19 TP, TURRET, 0.064" MILL-MAX, 2308-2-00-44 dc1781af 6 DEMO MANUAL DC1781A SCHEMATIC DIAGRAM dc1781af 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. 7 DEMO MANUAL DC1781A 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 dc1781af 8 Linear Technology Corporation LT 0711 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2011