DEMO MANUAL DC2234A LT8711 Micropower Synchronous Sepic Converter Description Demonstration circuit 2234A is a synchronous sepic converter featuring the LT®8711 multitopology switching controller. The LT8711 is a current mode PWM DC/DC controller with a dual input LDO to optimize gate driver efficiency. Ultralow 15μA quiescent current in low noise Burst Mode® operation achieves high efficiency at very light loads and helps extend the run-time in battery powered applications when in standby mode. The LT8711 switching frequency can be programmed either via oscillator resistor or external clock over a 100kHz to 750kHz range. The DC2234A can be modified from a SEPIC converter to other topologies. Synchronous BOOST and some other schematics are provided in the data sheet. Please consult the factory or LT8711 data sheet for details regarding how to customize the DC2234A or how to design different topologies for custom specifications. The demo board regulates a 12V, 4A output from a 4.5V to 40V input source, and operates at 200kHz switching frequency. The rated maximum load current is 4A, while derating is necessary for certain input voltage and thermal conditions. The data sheet gives a complete description of the device, operation and application information. The data sheet must be read in conjunction with this demo manual for DC2234A. The LT8711 is assembled in a 20-lead plastic TSSOP package with a thermally enhanced ground pad. Proper board layout is essential for maximum thermal performance. See the Layout Considerations section in the data sheet. The SYNC pin on the demo board is grounded (JP1 at BURST position) by default for low ripple high efficiency Burst Mode operation at light load. To synchronize to an external clock, move JP1 to SYNC and apply the external clock to the SYNC turret. Force continuous conduction mode can be selected by moving JP1 shunt to FCM position. The LT8711 includes many other features such as user configurable under voltage lockout, soft-start, input voltage feedforward regulation, and it is easily configured as synchronous buck, boost, SEPIC or nonsynchronous buck-boost converter. Design files for this circuit board are available at http://www.linear.com/demo/DC2234A L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners. Performance Summary Specifications are at TA = 25°C SYMBOL PARAMETER CONDITIONS VIN Input Voltage Range VOUT Output Voltage IOUT Maximum Output Current tSW Switching Frequency EFF Efficiency at DC MIN TYP 4.5 11.6 Derating is Necessary for Certain VIN and Thermal Conditions 40 12 12.4 4 185 VIN = 5V, IOUT = 1A VIN = 12V, IOUT = 2A VIN = 24V, IOUT = 4A VIN = 36V, IOUT = 4A MAX UNITS V V A 200 91.9 92 91.4 90.2 215 kHz % % % % dc2234af 1 DEMO MANUAL DC2234A Quick Start Procedure DC2234A is easy to set up to evaluate the performance of the LT8711. Refer to Figure 3 for proper measurement equipment setup and follow the procedure below: b. A voltmeter can be placed across the output terminals in order to get an accurate output voltage measurement. NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. See Figure 4 for the proper scope technique. 6. Turn on the power at the input. 1. Set an input power supply that is capable of 40V/12A. Then turn off the supply. 2. With power off, connect the supply to the input terminals VIN and GND. 3. Turn on the power at the input. NOTE: Make sure that the input voltage never exceeds 40V. 4. Check for the proper output voltage of 12V. Turn off the power at the input. NOTE: If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 7. Once the proper output voltage is again established, adjust the load and/or input within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other desired parameters. 8. An external clock can be added to the SYNC terminal when SYNC function is used (JP1 on the SYNC position). Please ensure that the chosen RT sets the LT8711 switching frequency to equal or below the lowest SYNC frequency. See the data sheet section, Clock Synchronization. 5. Once the proper output voltage is established, connect a variable load capable of sinking 4A at 12V to the output terminals VOUT and GND. Set the current for 0A. a. If efficiency measurements are desired, an ammeter can be put in series with the output load in order to measure the DC2234A’s output current. dc2234af 2 DEMO MANUAL DC2234A Quick Start Procedure 100 95 EFFICIENCY (%) 90 85 80 75 70 65 5V INPUT 12V INPUT 24V INPUT 36V INPUT 60 55 50 0 0.5 1 1.5 2.5 2 IOUT (A) 3 4 3.5 DC2234a F01 Figure 1. Efficiency vs Load Current at 200kHz Switching Frequency N-FET Temperature Rise 120 IOUT = 2A IOUT = 3A IOUT = 4A 80 60 40 20 0 IOUT = 2A IOUT = 3A IOUT = 4A 90 TEMPERATURE RISING (°C) 100 TEMPERATURE RISING (°C) P-FET Temperature Rise 100 80 70 60 50 40 30 20 10 0 5 10 15 30 20 25 INPUT VOLTAGE (V) 35 40 45 0 0 5 10 15 30 20 25 INPUT VOLTAGE (V) 35 40 45 DC2234a F02 Figure 2. DC2234A Temperature Rising vs Input Voltage dc2234af 3 DEMO MANUAL DC2234A Quick Start Procedure Figure 3. Proper Measurement Equipment Setup Figure 4. Measuring Output Ripple Figure 5. DC2234A 12V Input 2A to 4A Load Transient dc2234af 4 DEMO MANUAL DC2234A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 6 C2, C3, C4, CIN2, CIN3, CIN4 CAP, X7R, 10µF, 50V, 10% 1210 MURATA, GRM32ER71H106KA12L 2 1 CO1 ALUM, POLYMER, 270µF, 16V, 20% PANASONIC, 16SVPC270M 3 3 CO2, CO3, CO4 CAP, X7R, 22µF, 25V, 10% 1210 MURATA, GRM32ER71E226KE15L 4 1 CO7 CAP, X7R, 10µF, 25V, 10% 1206 MURATA, GRM31CR71E106KA12L 5 1 C7 CAP, X7R, 10nF, 25V, 10% 0603 MURATA, GRM188R71E103KA01D 6 4 C11, C14, C18, C22 CAP, X7R, 2.2µF, 16V, 10% 0805 MURATA, GRM21BR71C225KA12L 7 1 C13 CAP, X7R, 4.7µF, 50V, 10% 1206 TDK, C3216X7R1H475K160AC 8 1 C15 CAP, X7R, 4.7nF, 25V, 10% 0603 MURATA, GRM188R71E472KA01D 9 1 C16 CAP, C0G, 100pF, 50V, 5% 0603 TDK, C1608C0G1H101J080AA 10 1 C17 CAP, X7R, 0.47µF 16V 10% 0603 MURATA, GRM188R71C474KA88D 11 1 C19 CAP, X7R, 1000pF, 100V, 10% 1206 MURATA, GRM319R72A102KA01D 12 1 D1 DIODE, 60V, 2A, POWERDI-123 DIODES INC, DFLS260-7 13 1 D2 DIODE, 80V, 125mA, SOD-523 DIODES INC, 1N4148WT-7 14 1 L2 IND, 8.2µH COILCRAFT, XAL1510-822MEB 15 1 L3 IND, 15µH COILCRAFT, XAL1510-153MEB 16 1 MN1 N-MOSFET, 80V, POWERPAK SO-8 VISHAY, SIR826ADP-T1-GE3 17 1 MP1 P-MOSFET, 60V, POWERFLAT 5x6 STMicroelectronics, STL42P6LLF6 18 2 R1, R3 RES, SENSE, 0.002Ω, 1.5W, 2%, KRL3216 SUSUMU, KRL3216E-C-R002-G-T5 19 6 R5, R9, R12, R14, R18, R19 RES, CHIP, 0Ω, 0.1W, 0603 NIC, NRC06ZOTRF 20 1 R6 RES, CHIP, 3.3Ω, 0.1W, 1%, 0603 VISHAY, CRCW06033R30FKEA 21 2 R7, R15 RES, CHIP, 10Ω, 0.1W, 1%, 0603 VISHAY, CRCW060310R0FKEA 22 1 R13 RES, CHIP, 1M, 0.1W, 1%, 0603 VISHAY, CRCW06031M00FKEA 23 1 R16 RES, CHIP, 71.5k, 0.1W, 1%, 0603 VISHAY, CRCW060371K5FKEA 24 2 R17,R23 RES, CHIP, 100k, 0.1W, 1%, 0603 NIC, NRC06F1003TRF 25 1 R21 RES, CHIP, 118k, 0.1W, 1%, 0603 NIC, NRC06F1183TRF 26 1 R22 RES, CHIP, 49.9k, 0.1W, 1%, 0603 VISHAY, CRCW060349K9FKEA 27 1 R24 RES, CHIP, 3.3Ω, 1/2W, 5%, 1210 VISHAY, CRCW12103R30JNEA 28 1 U1 IC, LT8711EFE 20-LEAD TSSOP LINEAR TECH, LT8711EFE#PBF EP-CAP, 56µF, 50V, HVH SERIES SUN ELECT, 50HVH56M Additional Demo Board Circuit Components 1 1 CIN1 2 0 CIN5, CIN6, CO5, CO6, C20(OPT) CAP, 1210 3 0 C1 (OPT) CAP, 2220 4 0 C6, C8, C9, C10, C12, C21(OPT) CAP, 0603 5 0 L1 (OPT) IND, 8.2µH 6 0 MN2 (OPT) N-MOSFET, POWERPAK SO-8 7 0 MP2 (OPT) P-MOSFET, POWERFLAT 5x6 8 0 R4 (OPT) RES, 1210 9 0 R20 (OPT) RES, 0603 dc2234af 5 DEMO MANUAL DC2234A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Hardware: For Demo Board Only 1 11 E1 TO E11 TESTPOINT, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0 2 1 JP1 DOUBLE ROW HEADER 2 x 3 0.079" WURTH ELEKTRONIK, 62000621121 3 1 XJP1 SHUNT, 0.079" CENTER WURTH ELEKTRONIK, 60800213421 4 4 MH1 TO MH4 STAND-OFF, NYLON 0.50" TALL KEYSTONE, 8833 (SNAP ON) dc2234af 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. A B C D SYNC AGND EN/FBIN PGND VIN 4.5V - 40V E11 E10 E9 E4 E3 E2 E1 5 SYNC EN/FBIN 56uF 50V 50HVH56M + CIN1 VIN MN2 OPT 1 3 5 JP1 R1 0.002 KRL3216E INTVCC 2 MN1 SiR826ADP CIN6 1210 CIN5 OPT 2 4 6 VIN BURST C4 1210 C3 10uF C9 OPT C13 4.7uF 50V 1206 NG R24 3.3 1210 C19 1nF 100V 1206 4 1. ALL RESISTORS ARE 0603. ALL SMD CAPACITORS ARE 0603. BG C14 2.2uF 0805 INTVCC R17 100K 13 1 14 16 17 INTVCC EN/FBIN VIN CSN CSP U1 LT8711EFE 3.3 R6 MP2 OPT R5 0 D1 DFLS260 MP1 STL42P6LLF6 D2 1N4148 SOD-523 1 2 C20 OPT 1210 C7 10nF R20 OPT C10 OPT SYNC FCM R18 0 10 R15 10 R7 4 3 OPT 2220 OPT 1210 C2 50V C1 NOTE: UNLESS OTHERWISE SPECIFIED CIN4 1210 CIN3 10uF CIN2 50V L1B OPT L2 8.2uH XAL1510-822 8 7 6 5 1 2 3 R4 C12 OPT 3 C17 470nF 3 R23 100K 4 R9 0 OPT C6 (200kHz) R21 118k VC EXTVCC INTVEE BIAS FB ISN KRL3216E R3 0.002 L3 15uH XAL1510-153 1 L1A OPT ISP 6 4 BG 11 OPMODE 5 SYNC 19 10 TG SS 4 SS ISP RT RT 20 ISN 7 NC 12 GND 21 NC 18 5 INTVEE 8 3 R22 49.9K C15 4.7nF VC BIAS 15 FB 2 9 C21 OPT R12 0 C16 100pF R16 71.5k C8 OPT 1M R13 2 C11 2.2uF 0805 R14 0 2 VOUT C22 2.2uF 0805 CO5 CO6 OPT 1210 C18 2.2uF 0805 R19 0 CO4 1210 CO3 25V CO2 22uF + CO1 270uF 16V 16SVPC270M 1 1 CO7 10uF 25V 1206 E8 E7 E6 E5 PGND VOUT 12V / 4A (VIN > 5V) A B C D DEMO MANUAL DC2234A Schematic Diagram dc2234af 7 DEMO MANUAL DC2234A 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 dc2234af 8 LT 0917 • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2017