DEMO MANUAL DC2008A LTC1625 High Efficiency Synchronous Buck Converter DESCRIPTION Demonstration circuit DC2008 is DC/DC buck converter featuring the LTC®1625 constant frequency current mode buck controller. The DC2008A operates over a 4.5V to 28V input and provides 15A of output current as shown in Figure 3. The 225kHz constant frequency operation results in a small and efficient circuit. The converter provides high output voltage accuracy (typically ±3%) over a wide load range with no minimum load requirement. The demonstration circuit can be easily modified to generate different output voltages. PERFORMANCE SUMMARY The DC2008 has small circuit footprint. It is a high performance and cost effective solution for telecom, automotive and industrial applications. 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. Specifications are at TA = 25°C PARAMETER CONDITIONS UNITS Minimum Input Voltage IOUT = 0A to 15A 4.5V Maximum Input Voltage IOUT = 0A to 15A 28V VOUT VIN = 4.5V to 28V, IOUT = 0A to 15A 3.3V ±3% Typical Output Ripple VOUT VIN = 4.5V to 28V, IOUT = 15A 50mVP-P Nominal Switching Frequency 225kHz QUICK START PROCEDURE Demonstration circuit DC2008 is easy to set up to evaluate the performance of the LTC1625. For proper measurement equipment setup refer to Figure 1 and follow the procedure below: Note: When measuring the input or output voltage ripple, care must be taken to minimize the length of oscilloscope probe ground lead. Measure the input or output voltage ripple by connecting the probe tip directly across the VIN or VOUT and GND terminals as shown in Figure 2. 1.With power off, connect the input power supply to VIN and GND. 2.Check the EXTVCC bias voltage-setting jumper JP1. Remove it for internal VCC bias if required. 3.Turn the input power source on and slowly increase the input voltage. Be careful not to exceed 28V. Note: Make sure that the input voltage VIN does not exceed 28V. If higher operating voltage is required, power components with higher voltage ratings should be used. 4.Set the input voltage to 6V and check for the proper output voltage of 3.3V. If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 5.Once the proper output voltage is established, adjust the load and observe the output voltage regulation, ripple voltage, efficiency and other parameters. dc2008af 1 DEMO MANUAL DC2008A QUICK START PROCEDURE Figure 1. Proper Measurement Equipment Setup VIN GND Figure 2. Measuring Input or Output Ripple Changing The Output Voltage To change the output voltage change the bottom voltage divider resistors connected to LTC1625 FB pin (see the Schematic Diagram). Please refer to data sheet for details. Note that the output voltage will start following the input voltage when input voltage is lower than the voltage set by the voltage divider. In this mode the top synchronous MOSFET is turned continuously ON. The only losses in this mode are due to the DCR of inductor and top MOSFET DC resistance. In this mode the LTC1625 has a repetitive short pulses that are used to refresh the top MOSFET drive circuit. dc2008af 2 DEMO MANUAL DC2008A QUICK START PROCEDURE Converter Efficiency And Output Current The DC2008 output current capability depends on the components used. Typical performance of DC2008A is shown in Figure 3. If bulk input capacitors are required use sufficient numbers of low ESR type of capacitors like aluminum polymer. Please consult LTC factory for details on selecting proper input and output capacitors. The Schematic Diagram can be modified for lower or higher currents and output voltages. Please contact LTC factory for details. The load step response of DC2008A is very good even though relatively small amount of output capacitance is present at the output. If higher load steps need to be handled or lower transients are required, more output capacitance can be added in order to keep the voltage transients at the desired level. The load step transients are shown in Figure 4. Also, note that the load step response even from 0% load is excellent thanks to synchronous operation. 96 94 EFFICIENCY (%) Output Load Step Response 98 92 90 88 86 84 5V INPUT 12V INPUT 24V INPUT 82 80 0 2 4 6 8 10 12 14 16 18 20 22 IOUT (A) DC2000A F03 Figure 3. High Efficiency of DC2008 Allows the Board to be Used in Thermally Critical Applications with Outputs Over 15A Beware that the load steps on the output will demand current steps on the input. The DC2008A demo board responds fast to load transients, which demands fast response from the input power source. Monitor the input voltage at the DC2008A input terminals to ensure that the input power source is capable of supplying such fast load current demands. Input And Output Filtering The DC2008 is equipped with adequate amount of input and output filtering. The input and output voltage ripples with a 10A load are shown in Figure 5. Also, the switch node waveform is shown for reference. Figure 4. Fast Transient Response of the DC2008 Is Achieved with a Relatively Small Amount of Output Capacitance The output ripple voltage will stay constant regardless of the load. Some of the output capacitors could be removed at the expense of output ripple voltage and load transient response. The input ripple voltage is dependent on the output load current. The input capacitors were selected based on the amount of RMS ripple current that needs to be handled. Beware that adding high ESR electrolytic capacitors at the input may result in high power dissipation in the capacitors. Figure 5. The DC2008 Has Very Low Output Ripple Voltage. The Input Ripple Voltage, if Required, Can Be Further Reduced By More Input Capacitance of by Adding a Small LC Filter dc2008af 3 DEMO MANUAL DC2008A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 CC1 CAP., X7R, 15nF, 25V, 10% 0603 KEMET, C0603C153J3GACTU 2 1 CC2 CAP., X7R, 1nF, 50V, 10% 0603 YAGEO., CC0603KRX7R9BB102 3 1 C3 CAP., X5R, 0.1µF, 16V, 10%, 0603 KEMET, C0603C104K4RACTU 4 1 CF CAP., X5R, 0.1µF, 50V, 10%, 0603 TDK, CGA3E2X5R1H104K080AA 5 6 CIN1-CIN6 CAP., X5R, 6.8µF, 50V, 10%, 1812 TDK, C4532X7R1H685K 6 2 COUT5, COUT6 CAP., X5R, 100µF, 10V, 20%, 1812 TDK, C4532X5R1A107M280KC 7 4 COUT1-COUT4 CAP., TANT, 680µF,6.3V,7343 KEMET, T530X687M006A1E010 8 1 CVCC1 CAP., X5R, 4.7µF, 6.3V, 10%, 0805 TAIYO YUDEN JMK212BJ475KD-T 9 1 C2 CAP., X7R, 0.47µF, 6.3V, 10%, 0805 TDK, CGJ4J2X7R0J474K 10 1 D2 DIODE, SCHOTTKY, SOD-323 CENTRAL, CMDSH4E 11 1 D3 DIODE., SCHOTTKY, SMA, DIODE, B340A-13-F 12 1 L1 IND., 3.5µH WÜRTH ELEKTRONIK, 7443556350 13 2 Q1,Q4 NPN/PNP TRANSISTOR., SC-74 NXP SEMI., PBSS4140DPN 14 1 Q5 N-CHANNEL MOSFET, LFPAK RENESAS, RJK0453DPB-T-E3 15 1 Q2 N-CHANNEL MOSFET, LFPAK RENESAS, RJK0452DPB-T-E3 16 1 RC1 RES., CHIP, 15k, 1%, 0603 CRCW060315K0FKEA 17 1 RF RES., CHIP, 1.0Ω, 1%, 0603 VISHAY,CRCW06031R00FKEA 18 1 R1 RES., CHIP, 10Ω, 1%, 0603 VISHAY, CRCW060310R0FKEA 19 1 R3 RES., CHIP, 0Ω, 0603 VISHAY, CRCW06030R00FKEA 20 1 R4 RES., CHIP, 21k, 1%, 0603 KOA Speer Electronics, RK73H1JTTD2102F 21 1 R5 RES., CHIP, 11.8k, 1%, 0603 VISHAY, CRCW060311K8FKEA 22 1 U1 LTC1625IGN, GN PACKAGE 16-PIN LINEAR TECH., LTC1625IGN Additional Demo Board Circuit Components 1 0 CIN7, OPT CAP., OPTIONAL 2 1 CE CAP., X5R, 0.1µF, 16V, 10%, 0603 KEMET, C0603C104K4RACTU 3 1 DZ DIODE., 350mW, 5% ,SOD-323 PHILIPS, PDZ6.8B 4 1 Q3 TRANSISTOR., NPN SOT-89 ZETEX, FCX619 5 1 RZ RES., CHIP, 4.7k, 5%, 0603 VISHAY, CRCW06034K70JNED MILL-MAX, 2501-2-00-80-00-00-07-0 Hardware-For Demo Board Only 1 6 E4-E9 TESTPOINT, TURRET, 0.095" 2 4 STAND OFF STAND OFF KEYSTONE, 8833 3 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 2008A 4 1 STENCIL TOP AND BOTTOM STENCIL DC2008A 5 1 JP1 0.079 SINGLE ROW HEADER, 2-PIN SAMTEC, TMM102-02-LS 6 2 JP2,JP3 0.079 SINGLE ROW HEADER, 3-PIN SAMTEC, TMM-103-02-L-S 7 3 JP1-JP3 SHUNT SAMTEC, 2SN-BK-G 8 4 J1-J4 STUD, TEST PIN PEM KFH-032-10 9 8 J1-J4 (X2) NUT, BRASS 10-32 ANY #10-32 10 4 J1-J4 RING, LUG #10 KEYSTONE #10 11 4 J1-J4 WASHER, TIN PLATED BRASS ANY #10 dc2008af 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 SGND RUN/SS E6 E4 5 2 1 3 C CCM BURST INTVCC JP2 MODE 2 1 3 C3 0.1uF 16V 150KHz 225KHz JP3 FSW 4 VOUT CC1 15nF RC1 15k DZ PDZ6.8B RZ 4.7k 1 2 E Q3 FCX619 R5 11.8k 21k 1% R4 CC2 1nF CE 0.1uF B C 7 6 5 4 3 2 1 U1 LTC1625IGN VOSENSE SGND ITH FCB RUN/SS SYNC EXTVCC CF 0.1uF 16 VIN 50V 3 VPROG BG PGND INTVCC BOOST SW TK TG 8 10 9 11 12 14 15 13 1 0 4 1 2 4 1 4 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 2 Q2 L1 3.5uH D3 B340A 7443556350 SCALE = NONE HZ APPROVALS COUT1 6.8uF 50V 1812 E7 TECHNOLOGY DATE E9 J4 J3 E8 -VIN GND -VOUT GND VOUT 3.3V / 15A +VOUT VIN 4.5V - 28V +VIN 7-31-13 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only 1812 J2 J1 E5 Goran P. DATE: N/A SIZE 1 LTC1625IGN DEMO CIRCUIT 2008A Tuesday, October 29, 2013 IC NO. SHEET 1 OF 1 2 REV. LTC1625, SYNCHRONOUS STEP-DOWN REGULATOR TITLE: SCHEMATIC 6.3V 7343 1 APPROVED VOUT COUT5 + COUT6 100uF 10V + CIN7 OPT 35V PRODUCTION DESCRIPTION REVISION HISTORY COUT2 + COUT3 COUT4 680uF CIN1 CIN2 CIN3 CIN4 CIN5 CIN6 2 REV RJK0452DPB __ ECO Q5 RJK0453DPB SW LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A Goran P. 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. 4 Q4 PBSS4140DPN R1 10 5 2 PBSS4140DPN Q1 CUSTOMER NOTICE R3 5 2 INTVCC CMDSH-4E D2 C2 0.47uF 16V CVCC1 4.7uF 10V 2 EXTVCC JP1 VIN 6 3 RF 1.0 6 3 5 1 2 3 3 5 1 2 3 4 1 2 D 5 A B C D DEMO MANUAL DC2008A SCHEMATIC DIAGRAM dc2008af 5 DEMO MANUAL DC2008A 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 dc2008af 6 Linear Technology Corporation LT 1113 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013