DEMO MANUAL DC1822A LTC3861EUHE High Current, Dual Output Synchronous Buck Converter Description Demonstration circuit 1822A is a dual output synchronous buck converter featuring the LTC®3861EUHE. The board provides two outputs of 1.5V/25A and 1.2V/25A from an input voltage of 7V to 14V at a switching frequency of 500kHz. The power stage consists of a 6mm × 6mm DrMOS and a 13mm × 13mm iron powder type inductor. An on-board 5V LT®3470 buck regulator provides the 5V bias for the LTC3861 and the DrMOS. The demo board uses a high density, two sided drop-in layout. The power components, excluding the bulk output and input capacitors, fit within a 1.5" × 1.2" area on the top layer. The control circuit fits in a 1.1" × 1.0" area on the bottom layer. The package style for the LTC3861EUHE is a 36-lead 5mm × 6mm QFN. L, LT, LTC, LTM, µModule, 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 The main features of the board are: • Remote sensing for each output, where the divider is placed before a high input impedance differential amplifier. • CLKIN and CLKOUT pins. • Optional resistors to tie the two outputs together. • Connector and header to tie two or more boards together for up to 12-phase operation. • Optional footprint for an LTC4449 gate driver and discrete MOSFETs. • Optional footprint for a dual phase Delta power block. Design files for this circuit board are available at http://www.linear.com/demo (TA = 25°C), no airflow CONDITION Minimum Input Voltage VALUE 7V Maximum Input Voltage 14V Output Voltage VOUT1 IOUT1 = 0A to 25A, VIN = 7V to 14V 1.5V ±2% Output Voltage VOUT2 IOUT2 = 0A to 25A, VIN = 7V to 14V 1.2V ±2% VOUT1 Maximum Output Current, IOUT1 VIN = 7V to 14V, VOUT1 = 1.5V 25A VOUT2 Maximum Output Current, IOUT2 VIN = 7V to 14V, VOUT2 = 1.2V 25A Nominal Switching Frequency Efficiency (See Figures 2 and 3) 500kHz VOUT1 = 1.5V, IOUT1 = 25A, VIN = 12V 91.6% Typical VOUT2 = 1.2V, IOUT2 = 25A, VIN = 12V 90.7% Typical dc1822af 1 DEMO MANUAL DC1822A Quick Start Procedure Demonstration circuit 1822A is easy to set up to evaluate the performance of the LTC3861EUHE. Please refer to Figure 1 for proper measurement equipment setup and follow the procedure below. 1.With power off, connect the input 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: JP1RUN1 ON JP2 RUN2 ON JP3 ON INT BIAS 2.Adjust the input voltage to be between 7V to 14V. VOUT1 should be 1.5V ±2%.VOUT2 should be 1.2V ± 2%. – VOUT1 LOAD 3.Next, apply 25A load to each output and re-measure VOUT. 4. Once the DC regulation is confirmed, observe the output voltage ripple, load step response, efficiency and other parameters. NOTE 1. Use the BNC connectors labeled VOUT1 or VOUT2 to measure the output voltage ripple. NOTE 2. Do not apply the load from the VOS1+ turret to the VOS1– turret or from the VOS2+ turret to the VOS2– turret. These are connected to the sense traces for the output voltage. Heavy load currents applied across these turrets may damage these traces. + + A A IOUT1 VOUT2 LOAD – IOUT2 Monitor voltage across COUT5 and COUT10 for accurate efficiency measurements. + + VOUT1 * VOUT2 V V – – * + VIN V – dc1822a F01 IIN A + VIN SUPPLY – Figure 1. Proper Measurement Equipment Setup dc1822af 2 DEMO MANUAL DC1822A quick start procedure DYNAMIC LOAD CIRCUIT (OPTIONAL) 1.Preset the amplitude of a pulse generator to 0.0V and the duty cycle to 5% or less. 2.Connect the scope to the VOUT BNC connectors for the rail under test with a coax cable. To monitor the load step current, connect the scope probe across the ISTEP± turrets for that rail. 3. Connect the output of the pulse generator to the PULSE GEN turret for the rail under test and connect the return to one of the GND turrets. 4.With the converter running, slowly increase the amplitude of the pulse generator output to provide the desired load step pulse height. The scaling for the load step signal is 10mV/Amp. See Figures 4 and 5 for transient response curves with a 50% load change. 95 Efficiency (%) 90 85 Parameters and conditions: RBOOST = 2.2Ω (R2, R25) L = Würth 744355147 (0.47µH, DCR = 0.67mΩ ±10%) External 5V bias applied Power from the external 5V bias included in the efficiency measurements 1.2V rail disabled No airflow 80 75 70 0 5 10 15 Load Current (Amps) VIN = 7V VIN = 12V 20 25 VIN = 14V 30 dc1822a F02 Figure 2. Efficiency Curves for the 1.5V Rail of the DC1822A. fSW = 500kHz with the FDMF6820A DrMOS 95 Efficiency (%) 90 85 Parameters and conditions: RBOOST = 2.2Ω (R2, R25) L = Würth 744355147 (0.47µH, DCR = 0.67mΩ ±10%) External 5V bias applied Power from the external 5V bias included in the efficiency measurements 1.5V rail disabled No airflow 80 75 70 0 5 10 15 Load Current (Amps) VIN = 7V VIN = 12V 20 25 VIN = 14V 30 dc1822a F03 Figure 3. Efficiency Curves for the 1.2V Rail of the DC1822A. fSW = 500kHz with the FDMF6820A DrMOS dc1822af 3 DEMO MANUAL DC1822A quick start procedure 88mV 1.5VO(AC) 50mV/DIV 25A LOAD STEP 5A/DIV 12.5A 20µs/DIV dc1822a F04 Figure 4. Load Step Response of the DC1822A 1.5V Rail at VIN = 12V. COUT = 3× Sanyo 2R5TPE330M9 || 2× 100µF X5R 6.3V 1210, L = 0.47µH, fSW = 500kHz 91mV 1.2VO(AC) 50mV/DIV 25A LOAD STEP 5A/DIV 12.5A 20µs/DIV dc1822a F05 Figure 5. Load Step Response of the DC1822A 1.2V Rail at VIN = 12V. COUT = 3× Sanyo 2R5TPE330M9 || 2× 100µF X5R 6.3V 1210, L = 0.47µH, fSW = 500kHz SINGLE OUTPUT/DUAL PHASE OPERATION A single output/dual phase converter may be preferred for higher output current applications. The optional components required to tie the phases together are found on the bottom of the schematic shown in Figure 8. To tie the two outputs together, make the following modifications: 1.Stuff 0Ω at R36 and R47 to tie the two outputs together. 2.Select one rail to be the master. • If VOUT1 is the master, then stuff 0Ω at R51 to disable the error amplifier for phase 2. Also stuff 0Ω at R52. • If VOUT2 is the master, then stuff 0Ω at R49 to disable the error amplifier for phase 1. Also stuff 0Ω at R50. 3.Remove the 0Ω jumper at R13 and stuff a 100pF capacitor at C14 for the IAVG signal. 4.Stuff 0Ω at R53, R48 and R54 to tie the COMP, TRK/SS and RUN pins together. 5.Remove the redundant compensation components. PARALLELING BOARDS The DC1822A demo boards can be tied together to form a converter with up to 12 phases. To tie the boards together, place the boards side-by-side and then connect the boards by connecting J8 of one board to J9 of the other. This will connect the IAVG, COMP, TRK/SS and signal ground signals together. Next, use copper strips to tie the VOUT planes, the VIN planes and GND planes of the two adjacent boards together. The board has exposed copper along the edges of the board for this purpose. Figure 6 shows how to set up a 4-phase converter and Figure 7 shows how to set up a 3-phase plus single phase converter. dc1822af 4 Cu VIN VOUT 0.0mΩ 0.0mΩ BOARD #1 BOARD #2 VOUT1 TO VOUT2 R36 & R47 NS NS ILIM1 TO VCC R50 0Ω 0Ω NS NS ILIM2 R R24 0Ω NS FB1 TO VCC R49 0Ω 0Ω FB2 TO VCC R51 0Ω 0Ω TRK/SS1 TO TRK/SS2 R48 0Ω 0Ω COMP1 TO COMP2 R53 0Ω 0Ω RUN1 TO RUN2 R54 Figure 6. Setup of a 4-Phase Converter; Phase 1 of Board 1 is the Master STUFF STUFF ILIM1 R R17 ILIM2 TO VCC R52 Note: Tie GND shapes together on the bottom layer by using the exposed copper along the edge of the board. VIN VOUT BOARD 2—TOP LAYER Cu VIN VOUT BOARD 1—TOP LAYER NS NS NS NS PHASE MODE SETTING R41 R42 VOUT 100pF dc1822a F06 NS NS IAVG PIN R13 100pF C14 DEMO MANUAL DC1822A quick start procedure dc1822af 5 6 VIN Cu VIN VOUT1 NS BOARD #2 NS NS ILIM1 TO VCC R50 STUFF STUFF ILIM1 R R17 NS 0Ω ILIM2 TO VCC R52 STUFF NS ILIM2 R R24 0Ω NS FB1 TO VCC R49 NS 0Ω FB2 TO VCC R51 NS 0Ω TRK/SS1 TO TRK/SS2 R48 NS 0Ω COMP1 TO COMP2 R53 NS 0Ω RUN1 TO RUN2 R54 0Ω NS NS NS PHASE MODE SETTING R41 R42 Single phase rail VOUT2 Figure 7. Setup of a 3-Phase Plus Single Phase Converter; Phase 1 of Board 1 Is the Master of the 3-Phase Rail 0.0mΩ BOARD #1 VOUT1 TO VOUT2 R36 & R47 Note: Tie GND shapes together on the bottom layer by using the exposed copper along the edge of the board. Triple phase rail VOUT1 BOARD 2—TOP LAYER Cu VIN VOUT1 BOARD 1—TOP LAYER 100pF dc1822a F07 NS NS IAVG PIN R13 100pF C14 DEMO MANUAL DC1822A quick start procedure dc1822af DEMO MANUAL DC1822A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER DC1822A Required Circuit Components 1 4 C1, C7, C8, C9 CAP, 0.22µF, 10%, 25V, X7R, 0603 AVX 06033C224KAT2A 2 2 C1-1, C1-2 CAP, 1500pF, 10%, 50V, GOG, 0603 MURATA,GRM1885C1H152JA01D 3 2 C2-1, C2-2 CAP, 100pF, 5%, 25V, NPO, 0603 AVX 06033A101JAT2A 4 2 C28, C29 CAP, 10µF, 20%, 6.3V, X5R, 0805 AVX 08056D106MAT2A 5 4 C3, C11, C34, C35 CAP, 2.2µF, 10%, 16V, X7R, 0603 MURATA GRM188R61C225KE15D 6 2 C3-1, C3-2 CAP, 3300pF, 10%, 50V X7R, 0603 AVX 06035C332KAT2A 7 1 C6 CAP, 1µF, 20%, 25V, X5R, 0603 AVX 06033D105MAT2A 8 1 CIN2 CAP, 180µF, 20%, 16V, OSCON SANYO 16SVP180MX 9 4 CIN3, CIN4, CIN5, CIN6 CAP, 22µF, 20%, 16V, X5R, 1210 AVX 1210YD226MAT2A 10 6 COUT1-COUT3, COUT6-COUT8 CAP, 330µF, 20%, 2.5V POSCAP 7343 SANYO 2R5TPE330M9 11 4 COUT4, COUT5, COUT9, COUT10 CAP, 100µF, 20%, 6.3V, X5R, 1210 AVX 12106D107MAT2A 12 2 L1,L2 IND, 0.47µH, 20% WURTH 744355147 13 2 R1, R45 RES, 18.2k, 1%, 1/10W, 0603 VISHAY CRCW060318K2FKEA 14 4 R11, R18, R39, R43 RES, 10Ω, 1%, 1/10W, 0603 VISHAY CRCW060310R0FKEA 15 2 R17, R24 RES, 53.6k, 1%, 1/10W, 0603 VISHAY CRCW060353K6FKEA 16 2 R2, R25 RES, 2.2Ω, 1%, 1/16W, 0603 VISHAY CRCW06032R20FKEA 17 2 R20, R38 RES, 2.87k, 1%, 1/10W, 0603 VISHAY CRCW06032K87FKEA 18 1 R2-1 RES, 9.76k, 1%, 1/16W, 0603 VISHAY CRCW06039K76FKEA 19 1 R2-2 RES, 9.31k, 1%, 1/16W, 0603 VISHAY CRCW06039K31FKEA 20 3 R3, R16, R26 RES, 1Ω, 1%, 1/10W, 0603 YAGEO RC0603FR-071RL 21 2 R3-1, R3-2 RES, 280Ω, 1%, 1/10W, 0603 VISHAY CRCW0603280RFKEA 22 1 R37 RES, 34k, 1%, 1/10W, 0603 VISHAY CRCW060334K0FKEA 23 2 R8, R44 RES, 100k, 1%, 1/10W, 0603 VISHAY CRCW0603100KFKEA 24 9 R9, R12, R13, R19, R21-R23, R32, R73 RES, 0Ω, JUMPER, 0603 VISHAY CRCW06030000Z0EA 25 11 RB-1, RB-2, RT-2, R1-1, R1-2, R4-R6, R29, R30, R46 RES, 10k, 1%, 1/10W, 0603 VISHAY CRCW060310K0FKEA 26 1 RT-1 RES, 15k, 1%, 1/10W, 0603 YAGEO RC0603FR-0715KL 27 1 U1 I.C., LTC3861EUHE LINEAR TECH. LTC3861EUHE#PBF 28 2 U2, U3 MOSFET, DrMOS, DC-DC, 3.3V, PWM FAIRCHILD FDMF6820A Additional Circuit Components 1 1 C17 CAP, 0.22µF, 10%, 25V, X7R, 0603 AVX 06033C224KAT2A 2 1 C18 CAP, 1µF, 20%, 25V, X5R, 0603 AVX 06033D105MAT2A 3 1 C19 CAP, 22µF, 20%, 16V, X5R, 1210 AVX 1210YD226MAT2A 4 2 C2, C4, C5, C10, C12-C16, C20, C22-C25, C27, C30-C33 CAP, 0603 OPT 5 1 C21 CAP, 22pF, 10%, 25V, NPO, 0603 AVX 06033A220KAT2A 6 1 C26 CAP, 1µF, 20%, 25V, X5R, 0603 AVX 06033D105MAT2A 7 0 CIN1 CAP, SVP, F8 OPT 8 0 CIN7-CIN14, COUT11-COUT17 CAP, 1210 OPT 9 0 COUT15-COUT17, COUT22-COUT24 CAP, 7343 OPT 10 0 D1 DIODE, BAV170, SOT23 OPT dc1822af 7 DEMO MANUAL DC1822A parts list ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER 11 0 D2, D3 CMDSH-3 OPT 12 1 L3 IND, 33µH, –53DLC TOKO A914BYW-330M=P3 13 0 L4 INDUCTOR, –53LDC OPT 14 0 PB1 DC/DC Converters, D12S1R845A OPT 15 2 Q1, Q2 MOSFET, 30V N-CHANNEL, DPAK VISHAY SUD50N03-12P-E3 16 0 Q3, Q4, Q7, Q8 BSC050NE2LS OPT 17 0 Q5, Q6, Q9, Q10 BSC010NE2LS OPT 18 0 R10, R14, R15, R27, R28, R31, R33-R35, R41, R42, R47-R55, R62, R64-R67, R69, R71, R72, R74-R81 RES, 0603 OPT 19 2 R56, R58 RES, 10k, 1%, 1/10W, 0603 VISHAY CRCW060310K0FKEA 20 2 R57, R60 RES, 0.010Ω, 1%, 1W, 2010 IRC LRC-LRF2010LF-01-R010-F 21 1 R59 RES, 0Ω, JUMPER, 1206 VISHAY CRCW12060000Z0EA 22 1 R61 RES, 604k, 1%, 1/16W, 0603 VISHAY CRCW0603604KFKEA 23 1 R63 RES, 200k, 1%, 1/16W, 0603 VISHAY CRCW0603200KFKEA 24 1 U4 BUCK REGULATOR, LT3470ETS8 LINEAR TECHNOLOGY LT3470ETS8 25 0 U5 BUCK REGULATOR, LT3470ETS8 OPT 26 0 U8, U9 N-CHANNEL MOSFET DRIVER, LTC4449 OPT 1 27 E1-E27 TESTPOINT, TURRET, 0.095" MILL-MAX 2501-2-00-80-00-00-07-0 2 6 J1-J6 STUD, TEST PIN PEM KFH-032-10 Hardware 3 12 J1-J6 NUT, BRASS PL #10-32 ANY #10-32M/S 4 6 J1-J6 RING, LUG #10 KEYSTONE 8205 5 6 J1-J6 WASHER, TIN, PLATED BRASS ANY 6 2 J7, J10 CON, BNC, 5 PINS CONNEX 112404 7 1 J8 HEADER, DOBL ROW, RT ANGLE, 2×4, 8 PIN MILL-MAX 802-10-008-20-001000 8 1 J9 SOCKET, DBL ROW, RT ANGLE, 2×4, 8 PIN MILL-MAX 803-43-008-20-001000 9 4 JP1, JP2, JP3, JP4 HEADER, 3 PIN, 0.079" SINGLE ROW SAMTEC TMM-103-02-L-S 10 4 MTGS AT 4 CORNERS STAND-OFF, NYLON 0.5" KEYSTONE 8833 (SNAP-ON) 11 4 XJP1, XJP2, XJP3, XJP4 SHUNT, 0.079" CENTER SAMTEC 2SN-BK-G dc1822af 8 1 2 3 4 A B C C U2 D + E + + TECHNOLOGY + E D Figure 8. DC1822A Demo Circuit Schematic B A 1 2 3 4 DEMO MANUAL DC1822A Schematic Diagram dc1822af 9 1 2 3 A B + C D D E TECHNOLOGY E Figure 9. DC1822A Demo Circuit Schematic + + 4 C + B + 10 + A 1 2 3 4 DEMO MANUAL DC1822A Schematic Diagram dc1822af DEMO MANUAL DC1822A Schematic Diagram Figure 10. DC1822A Demo Circuit Schematic dc1822af 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. 11 DEMO MANUAL DC1822A 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 dc1822af 12 Linear Technology Corporation LT 0612 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2012