DEMO MANUAL DC1270A LTC3852EUDD Low VIN, High Efficiency Step-Down DC/DC Converter DESCRIPTION Demonstration circuit 1270A is a low input voltage, high efficiency synchronous buck DC/DC converter with 2.7V to 5.5V input range. It can supply 15A maximum load current at 1.5V output. The demo board features the LTC®3852EUDD controller. The integrated charge pump provides 5V to the LTC3852’s control logic and gate drives, supporting a wide selection of logic-level N-channel power MOSFETs with high efficiency. The constant frequency current mode architecture allows a phase-lockable frequency of up to 750kHz. The LTC3852 is ideal for general purpose 3.3V systems, lithium-ion powered devices and distributed DC power systems. The LTC3852EUDD is in a 3mm × 5mm 24-Lead QFN package. The light load operation mode of the converter is determined with the FCB pin. Use JP2 jumper to select burst mode, discontinuous mode or forced continuous mode operation. Switching frequency is preset at about 400KHz. This frequency can be easily modified from 250kHz to 750kHz by changing the value of a resistor (R5). The converter can also be externally synchronized from 250kHz to 750kHz through MODE/PLLIN pin (PLLIN terminal on the board). To shut down the converter, one simple way is to force the RUN pin below 1.1V (JP1: OFF). The power good output (PGOOD terminal) is low when the output voltage exceeds the ±10% regulation window. 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 PARAMETER (TA = 25°C) CONDITION Input Voltage Range VALUE 2.7V to 5.5V VIN = 2.7V to 5.5V, IOUT = 0A to 15A 1.5V ±2% Maximum Output Current, IOUT VIN = 2.7V to 5.5V, VOUT = 1.5V 15A Typical Output Ripple VIN = 3.3V, IOUT = 15A (20MHz BW) 11mVP-P Typical Efficiency VIN = 3.3V, VOUT = 1.5V, IOUT = 15A 90.4% Output Voltage, VOUT Typical Switching Frequency 400kHz dc1270Af 1 DEMO MANUAL DC1270A QUICK START PROCEDURE Demonstration circuit 1270A is easy to set up to evaluate the performance of the LTC3852EUDD. Refer to Figure 1 for the proper measurement equipment setup and follow the procedure below: 1. With power off, connect the input power supply to VIN(2.7V to 5.5V) and GND (input return). 2. Connect the 1.5V output load between VOUT and GND (Initial load: no load). 3. Connect the DVMs to the input and outputs. 4. Turn on the input power supply and check for the proper output voltages. VOUT should be 1.5V ±2%. 5. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage and other parameters. Note: When measuring the output or input voltage ripple, do not use the long ground lead on the oscilloscope probe. See Figure 2 for the proper scope probe technique. Short, stiff leads need to be soldered to the (+) and (–) terminals of an output capacitor. The probe’s ground ring needs to touch the (–) lead and the probe tip needs to touch the (+) lead. OPTIONAL HIGH INPUT VOLTAGE (4V to 38V) OPERATION The LTC3852 can also be used for high input voltage applications (4V to 38V input), with the integrated charge pump bypassed: 1. Remove the 0Ω resistor from R3 and put the resistor at R26 position (disconnect VIN1 from VIN , and connect VIN2 from VIN). Remove R22 and R23. The C1 flying cap can also be removed. 2. The related power components, such as input/output capacitors, MOSFETs, and inductor, need to be changed to fit the new application specification. 1270A F01 Figure 1. Proper Measurement Equipment Setup dc1270Af 2 DEMO MANUAL DC1270A QUICK START PROCEDURE + _ COUT VOUT GND 1270A F02 Figure 2. Measuring Output Voltage Ripple 100 90 EFFICIENCY (%) 80 BM PS CCM 70 60 50 40 VIN = 3.3V VOUT = 1.5V IOUT = 15A_MAX FSW = 400kHz QTOP = 1 × SIR438DP QBOT = 1 × SIR438DP 30 20 10 0 0.01 0.10 10 1.0 LOAD CURRENT (A) 100 3060 TA02 Figure 3. Efficiency vs Load Current PARTS LIST ITEM REFERENCEDESCRIPTION QUANTITY DESCRIPTION MANUFACTURERS PART NUMBER Required Circuit Components 1 2 CIN2, CIN1 Cap., POSCAP 220μF 6.3V 20% 7343 SANYO 6TPE220MI 2 2 CIN6, CIN5 Cap., X5R 10μF 16V 20% 1206 Taiyo Yuden EMK316BJ106ML 3 1 COUT1 Cap., X5R 100μF 6.3V 20% 1210 AVX 12106D107MAT2A 4 2 COUT3, COUT4 Cap., POSCAP 330μF 4V 20% SANYO 4TPE330MI 5 1 C1 Cap., X5R 2.2μF 10V 10% 0603 Taiyo Yuden LMK107BJ225MA 6 4 C2, C7, C14, C15 Cap., X5R 4.7μF 10V 10% 0603 Taiyo Yuden LMK107BJ475KA 7 1 C3 Cap., X7R 100pF 25V 10% 0603 AVX 06033C101KAT2A 8 1 C4 Cap., X7R 0.01μF 100V 10% 0603 AVX 06031C103KAT2A 9 3 C5, C6, C11 Cap., X7R 0.1μF 25V 10% 0603 AVX 06033C104KAT2A 10 1 C8 Cap., X7R 2200pF 25V 20% 0603 AVX 06033C222MAT2A 11 1 C9 Cap., X7R 150pF 25V 10% 0603 AVX 06033C151KAT1A 12 2 C12, C16 Cap., NPO 1000pF 25V 10% 0603 AVX 06033A102KAT1A 13 1 D1 Schottky Diode, 30V Central Semi. CMDSH-3 14 1 L1 Inductor, 0.4uH Vitec 59PR9875N dc1270Af 3 DEMO MANUAL DC1270A PARTS LIST ITEM QUANTITY 15 2 REFERENCEDESCRIPTION DESCRIPTION MANUFACTURERS PART NUMBER Q1,mQ3 Mosfet-N Channel, 30V/45A LFPAK Renesas RJK0330DPB-00-J0 Q1,mQ3 (Alternate) Mosfet-N Channel, Reduced Qg, 25V SO-8 Vishay SiliconixSiR438DP 16 1 RS1 Res., 0.002 1/2W 1% 2010 Vishay WSL-2010-2L000-F-EA 17 3 R1, R16, R17 Res., Chip 100k 0.06W 5% 0603 Vishay CRCW0603104JNEA 18 1 R2 Res., Chip 10 0.06W 5% 0603 Vishay CRCW0603100JNEA 19 8 R3, R6, R10, R13, R22-R25 Res/Jumper, Chip 0Ω 1/16W 1 AMP 0603 Vishay CRCW0603000ZOEA 20 1 R5 Res., Chip 82.5k 0.06W 1% 0603 Vishay CRCW060382K5FKEA 21 1 R7 Res., Chip 1k 0.06W 5% 0603 Vishay CRCW06031K00JNEA 22 1 R9 Res., Chip 5.90k 0.06W 1% 0603 Vishay CRCW06035K90FKEA 23 2 R12, R11 Res., Chip 100 0.06W 5% 0603 Vishay CRCW0603100RJNEA 24 1 R19 Res., Chip 20k 0.06W 1% 0603 Vishay CRCW06032002FKEA 25 1 R20 Res., Chip 17.4k 0.06W 1% 0603 Vishay CRCW06031742FKEA 26 1 R21 Res/Jumper, Chip 0Ω 1/8W 1 AMP 0805 Vishay CRCW08050000ZOEA 27 1 U1 I.C., Volt. Reg. QFN(24)(UDD) 3mm × 5mm Linear Tech. Corp. LTC3852EUDD Additional Circuit Components 1 0 CIN3, CIN4 Cap., POSCAP 220μF 6.3V 20% 7343 Sanyo 6TPE220MI 2 0 COUT2 Cap., X5R 100μF 6.3V 20% 1210 AVX 12106D107MAT2A Sanyo 4TPE330MI 3 0 COUT5, COUT6 Cap., POSCAP 330μF 4V 20% 4 0 C13 Cap., 0603 5 0 Q4, Q2 N-Chan. Single, SO8-PWRPAK-SGL 6 0 R8, R14, R15, R26 Res., 0603 Hardware For Demo Board Only 1 9 E1-E4, E6 to E10 Turret, Testpoint Mill Max 2501-2-00-80-00-00-07-0 2 2 JP3, JP1 Headers, 3 Pins 2mm Ctrs. Samtec TMM-103-02-L-S 3 1 JP2 Headers, 4 Pins 2mm Ctrs. Samtec TMM-104-02-L-S 4 4 J1-J4 Connector, Banana Jack Keystone 575-4 5 3 XJP1 to XJP3 Shunt, 2mm Ctrs. Samtec 2SN-BK-G 6 4 Stand-Off, Nylon 0.5" Tall Keystone, 8833(Snap On) 7 1 FAB, Rev3 Printed Circuit Board Demo Circuit 1270A 8 2 Stencil Stencil #1270A dc1270Af 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 JP2 PGOOD TRACK OFF ON RUN EXTCLK E9 E8 JP1 RUN E6 JP3 3 2 1 3 FREQ/PLLFLTR 1 400K 2 4 3 5 C5 100K 1K R7 C4 C8 2200pF 0.01uF 1000pF C16 82.5K 1% 0.1uF R5 0 Ohm R13 INTVCC 100K R16 R9 0 Ohm R25 VIN 5.90K 100K R17 C11 0.1uF C9 150pF 10 3 22 21 23 20 19 SHDN PGOOD TRACK/SS RUN ITH 220uF 6.3V CIN3 (OPT) CIN4 (OPT) C- 12 4 11 25 4 6 9 FB SENSE- SENSE+ BG INTVCC VIN2 VPUMP BOOST SW TG VIN1 24 1 2 13 C7 4.7uF 10V 15 VIN2 C14 4.7uF 10V 14 INTVCC C15 4.7uF 10V 5 16 18 VIN VIN+ E2 17 4.7uF 10V C2 R3 0 Ohm GND1 GND GND2 NC NC U1 LTC3852EUDD FREQ/PLLFLTR C1 CIN2 220uF 6.3V J2 VIN 2.7V TO 5.5V CIN1 2.2uF 10V 7 0603 8 MODE/PLLIN C+ C3 100pF R2 10 GND + E3 PLLIN PS 1 2 J1 + B CCM R1 VIN- + BURST MODE E1 4 + C D 5 R22 R20 17.4K 1% R14 (OPT) 0 Ohm R10 0 Ohm R24 C12 1000pF R19 20K 1% 0 Ohm 0 Ohm R23 0 Ohm R6 (OPT) C13 3 0 Ohm 0805 R21 Q3 D1 CMDSH-3 0.1uF C6 Q1 3 CIN5 10uF 16V 1206 R15 (OPT) 59PR9875N Vitec L1 0.4uH NOTE: ECO 3 REV DESCRIPTION PRODUCTION RS1 R11 100 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. 2 COUT2 (OPT) + DATE: N/A SIZE APPROVED J3 E4 R26 (Opt) TECHNOLOGY VIN E10 VIN2 VOUT- GND DATE 08/23/10 IC NO. Tuesday, November 02, 2010 1 SHEET 1 OF 1 LOW VIN, HIGH EFFICIENCY STEP-DOWN DC/DC CONVERTER REV. LTC3852EUDD 3 DEMO CIRCUIT 1270A 1630 McCarthy Blvd. Milpitas, CA 95035 www.linear.com Phone: (408)432-1900 Fax: (408)434-0507 VIN2 E7 VOUT 1.5V / 15A VOUT+ CHARLIE Z. COUT3 COUT4 COUT5 COUT6 + + + 330uF 330uF (OPT) (OPT) 4V 4V J4 CHARLIE Z. TITLE: SCHEMATIC RB SCALE = NONE APP ENG. PCB DES. APPROVALS R12 100 COUT1 100uF 6.3V 2. WHEN DCR SENSING IS IMPLEMENTED, SHORT RS1 AND DO NOT POPULATE R11 AND R12. 0.002 1% 1 REVISION HISTORY 1. WHEN RESISTOR SENSING IS IMPLEMENTED DO NOT POPULATE R8 AND R15. CUSTOMER NOTICE Q4 (OPT) R8 (OPT) Q2 (OPT) CIN6 10uF 16V 1206 2 A B C D DEMO MANUAL DC1270A SCHEMATIC DIAGRAM dc1270Af 5 DEMO MANUAL DC1270A 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 dc1270Af 6 Linear Technology Corporation LT 1210 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2010