DEMO MANUAL DC1924A LT8705 80V VIN and VOUT Synchronous 4-Switch Buck-Boost DC/DC Controller DESCRIPTION Demonstration circuit 1924A is a high performance buckboost converter featuring the LT®8705 that can operate from input voltages above, below or equal to the output voltage. The demo board input range is 36V to 80V. The output is optimized for 48V at 5A, with the output current limit set at 7A. (The circuit will operate with lower input voltage than 36V if load current is reduced). The controller has integrated input current, input voltage, output current and output voltage regulators. The one regulator that wants to decrease current gets control over the compensation pin VC. The inductor current is controlled by the VC signal that is fed into a current comparator together with a ramp compensation signal. While the current mode control limits the inductor current both in normal and in reverse direction, these current limits have some variation as input voltage changes. The input and output current regulators offer more accurate current limits. The input voltage regulator is typically used in applications with solar panels or other high impedance power sources, and will reduce the current if the input voltage drops below the set point. The operating mode of the controller is determined through the MODE pin (jumper JP1) and can be set to discontinuous mode, forced continuous mode and Burst Mode® operation. The LT8705 is capable of bidirectional operation when operating in forced continuous mode. Additional circuitry may be needed depending on the application. The CLKOUT output and the SYNC input can be used to synchronize two DC1924A circuits with 180 degree phase shift. By feeding the LT8705 from a separate low voltage supply, the power dissipation can be reduced. To supply the LT8705 chip from an external voltage supply (> 6.4V), cut the trace as marked on the board to disconnect the EXTVCC pin from VOUT. The LT8705 will start when voltage is applied at the input (VIN pin), and when it is running it will draw current from the EXTVCC pin if the voltage is > 6.4V. Typical efficiency with 5A load is above 97% across a 36V to 72V input range using the supplied inductor. Lower core loss can be achieved by using a ferrite core inductor. The LT8705 data sheet gives a complete description of the part, operation and application information. The data sheet should be read in conjunction with this quick start guide for demo circuit 1924A. The input voltage range of the LT8705 itself is 2.8V (need EXTVCC > 6.4V) to 80V and the output range is 1.3V to 80V. The LT8705EUHF is assembled in a 38-Lead (5mm × 7mm) plastic QFN package with a thermal pad underneath the chip. Proper board layout is essential for maximum thermal and electrical performance. See the data sheet section Circuit Board Layout Checklist. Design files for this circuit board are available at http://www.linear.com/demo/DC1924A L, LT, LTC, LTM, Linear Technology Burst Mode and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. dc1924afa 1 DEMO MANUAL DC1924A Specifications are at TA = 25°C SYMBOL PARAMETER CONDITIONS VIN Input Supply Range Note: Output Power Is Limited When VIN < 30V VOUT Output Voltage 48 V IIN Maximum Load Current 5 A IOUT Output Current Limit 7 A fSW Switching Frequency EFF Efficiency at DC Input 100 11 95 98 10 90 97 9 85 96 8 80 95 7 94 6 93 5 EFFICIENCY (%) 12 99 4 55 90 2 50 89 1 45 0 40 0.01 48 54 60 VIN (V) EFFICIENCY EFFICIENCY FERRITE DISSIPATION DISSIPATION FERRITE 48 80 66 72 78 DC1924a F01a Figure 1a. Efficiency and Power Loss as Function of Input Voltage at 5A Load. Dotted Lines Show Increased Efficiency When the Inductor Is Replaced by a Ferrite Core Inductor (Coiltronics SER2918H-223KL) UNITS V 200 kHz 97.5 97.2 97.5 % % % 6 5 4 3 65 3 42 36 70 92 36 MAX 75 91 30 TYP 60 2 POWER LOSS (W) 100 88 MIN VIN = 36V, VOUT = 48V, IOUT = 5A VIN = 48V, VOUT = 48V, IOUT = 5A VIN = 72V, VOUT = 48V, IOUT = 5A DISSIPATION (W) EFFICIENCY (%) PERFORMANCE SUMMARY 1 0.1 1 LOAD CURRENT (A) EFFICIENCY EFFICIENCY FERRITE POWER LOSS POWER LOSS FERRITE 10 0 DC1924a F01b Figure 1b. Efficiency and Power Loss in CCM Buck Mode. VIN = 56V. Dotted Lines Show Increased Efficiency When the Inductor Is Replaced by a Ferrite Core Inductor (Coiltronics SER2918H-223KL) dc1924afa 2 DEMO MANUAL DC1924A QUICK START PROCEDURE 1.Demonstration circuit 1924A is easy to set up to evaluate the performance of the LT8705. Refer to Figure 2 for proper measurement equipment setup and follow the procedure below. 2.With power off, connect the input power supply to VIN (TP1) and GND (TP3). 3.Connect the SHDN terminal to ground with a clip-on lead to disable the board. 4.Apply 48V to the input. The power source must have greater than 12A capability if you want to evaluate the board with full load over the input range. 5.Remove the clip-on lead from SHDN to enable the board. 6.Note that the demo circuit will be enabled at VIN > 5.6V, when VIN is rising. If operation at very low input voltage is not wanted, increase the value of R11 to set the undervoltage shutdown at the wanted level. 7.Once the proper output voltage is established, adjust the load and the input voltage within the operating range and observe the output voltage regulation, ripple voltage and efficiency and other parameters as needed. When measuring input/output voltages, measure at the input/ output terminals of the board to avoid measurement error caused by voltage drops in cables. 8.To measure input/output voltage ripple, avoid a long ground lead on the oscilloscope probe, as it may pick up switching noise. A commonly accepted method is to remove the oscilloscope probe end cap and ground lead and set the 20MHz bandwidth limit on the oscilloscope. Measure the input/output voltage ripple by touching the probe tip directly to the positive terminal of the input or output capacitor. Connect the probe ground terminal to the board’s GND plane near the capacitor with a very short wire. dc1924afa 3 DEMO MANUAL DC1924A QUICK START PROCEDURE Figure 2. Test Setup dc1924afa 4 DEMO MANUAL DC1924A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 2 C13, C47 CAP CERM 0.22µF 10% 16V X5R 0603 TAIYO YUDEN EMK107BJ224KA-T 2 2 C14, C15 CAP CER 1000pF 16V 20% X7R 0603 AVX CORPORATION 0603YC102MAT4A 3 8 C41-C44, C48, C49-C51 CAP CER 4.7µF 100V X7S 1812 TDK C4532X7S2A475M 4 2 C46, C65 CAP CER 1.0µF 100V X7S 0805 TDK C2012X7S2A105K 5 4 C45, C52, C55, C64 CAP ALUM 220µF 100V 20% RADIAL UCC EKY-101ELL221MK25S 6 3 C56, C57, C58 CAP CER 4.7µF 16V 10% X5R 0603 TAIYO YUDEN, EMK107ABJ475KA-T 7 1 C59 CAP CER 1µF 16V 10% X7R 0603 TDK C1608X7R1C105K 8 1 C61 CAP CER 100nF 16V 10% X7R 0603 TDK C1608X7R1C104K 9 1 C62 CAP CER 220pF 25V 5% NP0 0603 NIC NMC0603NPO221J50TRPF 10 1 C63 CAP CER 3300pF 25V 5% NP0 0603 KEMET C0603C332J3GAC 11 2 D1, D2 RECTIFIERS ULTRA FAST RECTIFIER SINGLE CENTRAL SEMI CMMR1U-02 TR 12 4 D3, D4, D5, D6 LED SMARTLED GREEN 570NM 0603 LG L29K-G2J1-24-Z 13 1 L1 INDUCTOR POWER 22µH 11.0A SMD WÜRTH ELECTRONICS 74435572200 14 2 M1, M2 MOSFET N-CH 80V 55A TDSON-8 INFINEON BSC123N08NS3 G 15 2 M3, M4 MOSFET N-CH 60V 19A TDSON-8 INFINEON BSC039N06NS 16 2 R8, R9 RES 10.0Ω 1/10W 1% 0603 SMD VISHAY CRCW060310R0FKEA 17 1 R11 RES 71.5k 1/10W 1% 0603 SMD PANASONIC ERJ-3EKF7152V 18 1 R13 RES 392k 1/10W 0.1% 0603 SMD VISHAY MCT06030D3923BP100 19 1 R14 RES 20.0k 1/10W 1% 0603 SMD VISHAY CRCW060320K0FKEA 20 1 R16 RES 10.0k 1/10W 0.1% 0603 SMD PANASONIC ERA-3AEB103V 21 2 R27, R46 RES 100k 1/10W 1% 0603 SMD VISHAY CRCW0603100KFKEA 22 4 R38, R41, R51, R58 RES 2.00Ω 1/10W 1% 0603 SMD VISHAY CRCW06032R00FKEA 23 1 R40 RES 0.01Ω 3W 2512 5% SMD TT ELECTRONICS LRF3WLF-01-R010-J 24 4 R42, R43, R44, R45 RES 549Ω 1/10W 1% 0603 SMD VISHAY CRCW0603549RFKEA 25 1 R47 RES 210k 1/10W 1% 0603 SMD VISHAY CRCW0603210KFKEA 26 1 R49 RES 24.3k 1/10W 1% 0603 SMD VISHAY CRCW060324K3FKEA 27 1 R50 RES 56.2k 1/10W 1% 0603 SMD VISHAY CRCW060356K2FKEA 28 1 R57 RES 0.007Ω 1W 1% 2512 SMD VISHAY CRCW25127L000FEA 29 1 R62 RES 4.02Ω 1/10W 1% 0603 SMD VISHAY CRCW06034R02FKEA 30 1 U1 LT8705 SYNCHRONOUS 4 SWITCH BUCK-BOOST DC/DC CONTROLLER LINEAR TECH LT8705EUHF#PBF dc1924afa 5 DEMO MANUAL DC1924A PARTS LIST Additional Demo Board Circuit Components 1 0 C12, C60 CAP 0603 OPTION CAP 0603 OPTION 2 0 C53, C54, C66-C71 CAP 1812 OPTION CAP 1812 OPTION 3 0 M1-1, M2-1, M3-1, M4-1 MOSFET POWER56 OPTION MOSFET POWER56 OPTION 4 0 R53, R54, R59, R60 RES 0603 OPTION RES 0603 OPTION 5 5 R22, R39, R48, R55 RES 0.0Ω 1/10W 0603 SMD VISHAY CRCW06030000Z0EA 6 2 R56 RES 0.0Ω 1.5W 2512 SMD VISHAY CRCW25120000Z0EG Hardware: For Demo Board Only 1 1 JP1 CONN HEADER 4POS 2MM VERT T/H SAMTEC TMM-104-02-L-S 2 4 TP1, TP2, TP3, TP4 JACK NON-INSULATED 0.218" KEYSTONE 575-4 3 14 TP5, TP8-TP20 TERM SOLDER TURRET 0.094 MILL-MAX 25012-00-80-00-00-07-0 4 1 SHUNT1 CONN SHUNT 2MM 2POS SAMTEC 2SN-BK-G 5 4 MH1, MH2, MH3, MH4 6 1 SPACER STACKING #4 SCREW NYLON KEYSTONE ELECTRONICS 8833 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT #1924A dc1924afa 6 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. 1 2 3 6 C41 4.7µF 100V 1812 C42 4.7µF 100V 1812 C66 OPT. C67 OPT. TP12 AGND PGND TP3 TP11 SYNC TP9 SS TP8 LDO33 TP20 EXTVCC TP10 MODE TP5 /SHDN LDO33 VOUT 0 R55 DCM BURST FCM R54 OPT. R53 OPT. JP1 4 3 2 1 GATEVCC C46 1.0µF 100V 0805 3- CUT TRACE TO DISCONNECT EXTVCC FROM VOUT AND SUPPLY EXTVCC THROUGH TP20. 5 C54 OPT. GATEVCC C57 4.7µF C53 OPT. 2- ALL SMD CAPACITORS AND RESISTORS ARE 0603. 1- ALL SMD CAPACITORS ARE 16V. NOTES (UNLESS OTHERWISE SPECIFIED): ____________________________ SEE NOTE 3 R14 20K R11 71.5K R56 + C45 220µF 100V 0 2512 + C52 220µF 100V 15 35 5 1 C56 4.7µF FBIN 34 33 32 8 7 6 5 R38 2 C65 1.0µF 100V 0805 EXTVCC GATEVCC INTVCC FBIN #SHDN VIN CSPIN CSNIN 4 R58 2 TG1 M1-1 OPT C44 4.7µF 100V 1812 8 7 6 5 U1 LT8705EUHF 4.02 R62 C43 4.7µF 100V 1812 D1 2 1 1 2 3 1 2 3 R39 0 C47 0.22µF 4 4 LDO33 C58 4.7µF M2 C15 1nF C59 1µF R8 10 R60 OPT. OPT. M2-1 4 BSC123N08NS3 G 5 6 7 8 TP1 CMMR1U-02 4 TG1 22 L1 OPT. C12 R9 10 R46 100K R47 210K C14 1nF R40 0.010 1225 Wide R51 2 M3 BSC039N06NS 22µH 1 2 3 R48 0 4 8 7 6 5 1 2 3 R41 2 C61 R49 24.3K 0.1uF C60 OPT. 4 M3-1 OPT 19 1 2 3 1 2 3 7 6 5 C13 0.22µF CSPOUT N/C N/C 6 25 26 27 28 36 10 30 31 20 24 3 C63 3300pF 25V R50 56.2K FBOUT SRVO_FBIN SRVO_IIN SRVO_IOUT SRVO_FBOUT SWEN CLKOUT CSNOUT C62 220pF 25V M4-1 OPT. 8 7 6 5 TG2 R22 0 R59 OPT. 4 4 VIN 36V to 80V C48 4.7µF 100V 1812 C68 OPT. C69 OPT. CUSTOMER NOTICE C49 4.7µF 100V 1812 R57 0.007 2512 R16 10K LDO33 C70 OPT. R27 100K R43 549 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. C50 4.7µF 100V 1812 C71 OPT. APPROVALS R13 392K VOUT 2 SCALE = NONE LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. S. M. VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APP ENG. MEHDI A. APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. CMMR1U-02 M4 BSC039N06NS 8 SRVO_FBIN R42 549 SRVO_IIN C51 4.7µF 100V 1812 DATE: N/A SIZE + C55 220µF 100V R44 549 TECHNOLOGY R45 549 TP14 CLKOUT TP19 SWEN TP18 SRVO_FBOUT TP17 SRVO_IOUT TP16 SRVO_IIN TP15 SRVO_FBIN TP13 AGND TP4 PGND TP2 VOUT 48V / 5A 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only + C64 220µF 100V 1 1 DEMO CIRCUIT 1924A LT8705EUHF Thursday, June 26, 2014 IC NO. SHEET 1 2 OF 2 REV. 80V / 48V Synchronous Buck-Boost Controller TITLE: SCHEMATIC D4 M1 BSC123N08NS3 G D5 2 D6 3 SRVO_IOUT 4 SRVO_FBOUT 5 LDO33 4 TG1 EXTVCC 29 BOOST1 23 MODE 37 2 D2 1 3 2 1 21 SW1 SS 9 CSP BG1 BG1 3 AGND 14 SYNC 11 D3 5 6 7 8 8 7 6 5 13 1 2 3 2 1 RT 12 BG2 IMONOUT 1 2 BG2 7 2 CSN 16 IMONIN 38 1 2 TG2 18 TG2 17 PGND 39 SW2 VC 8 BOOST2 1 2 4 6 1 2 3 4 DEMO MANUAL DC1924A SCHEMATIC DIAGRAM dc1924afa 7 DEMO MANUAL DC1924A 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 dc1924afa 8 Linear Technology Corporation LT 0714 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013