DEMO MANUAL DC1881A LTC3789EUFD High Efficiency Compact Buck-Boost Converter DESCRIPTION Demonstration circuit 1881A is a high efficiency synchronous buck-boost DC/DC converter with 6V to 36V input range. It can supply 2.5A maximum load current at 12V output. The demo board features the LTC®3789EUFD controller. The constant-frequency current mode architecture allows a phase-lockable frequency of up to 600kHz, while an optional output current feedback loop provides support for applications such as battery charging. With a wide input range, wide output range and seamless transfers between operation modes, the LTC3789 is ideal for automotive, telecom, distributed DC power systems and battery-powered applications. This board has a compact solution size with dual SO-8 MOSFETs, small inductor and capacitor footprints. The package of LTC3789EUFD is a small, low thermal impedance 4mm × 5mm 28-Lead QFN. PERFORMANCE SUMMARY PARAMETER The light load operation mode of the converter is determined with the MODE/PLLIN pin. Use the JP2 jumper to select pulse skipping mode or forced continuous mode (CCM) operation. Switching frequency is preset at about 400kHz. The converter can also be externally synchronized through the MODE/PLLIN pin (PLLIN terminal on the board). To shut down the converter, one simple way is to force the RUN pin below 1.2V (JP1: OFF). The power good output (PGOOD terminal) is low when the output voltage is outside of the ±10% regulation window. Design files for this circuit board are available at http://www.linear.com/demo 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. Specifications are at TA = 25°C CONDITION Input Voltage Range VALUE 6V to 36V Output Voltage, VOUT VIN = 6V to 36V, IOUT = 0A to 2.5A Maximum Output Current, IOUT VIN = 6V to 36V, VOUT = 12V Typical Output Ripple VIN = 36V, IOUT = 12A (20MHz BW) 44mVP-P Typical Efficiency VIN = 12V, VOUT = 12V, IOUT = 2.5A 97.2% Typical Switching Frequency 12V ±2% 2.5A 400kHz dc1881af 1 DEMO MANUAL DC1881A QUICK START PROCEDURE Demonstration circuit 1881A is easy to set up to evaluate the performance of the LTC3789. 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 (6V to 36V) and GND (input return). 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. 2. Connect the 12V output load between VOUT and GND (Initial load: no load). Additional Notes: 3. Connect the DVMs to the input and outputs. 1. Usually, the worst case efficiency at full load is at 6VIN. The board can deliver more output power at higher VIN. 4. Turn on the input power supply and check for the proper output voltages. VOUT should be 12V ±2%. 2. R2 is needed for additional/constant output current limit only. 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. Figure 1. Proper Measurement Equipment Setup dc1881af 2 DEMO MANUAL DC1881A QUICK START PROCEDURE + – COUT VOUT GND Figure 2. Measuring Output Voltage Ripple 100 VIN = 12V EFFICIENCY (%) VIN = 24V 95 VIN = 6V VIN = 36V 90 85 0 0.5 1.0 1.5 LOAD CURRENT (A) 2.0 2.5 DC1881 F03 Figure 3. Efficiency vs Load Current (VO = 12V, CCM) PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 CC1 CAP., C0G, 100pF, 50V, 10% 0603 AVX, 06035A101KAT2A 2 1 CC2 CAP., X7R, 0.01μF, 50V, 10% 0603 AVX, 06035C103KAT2A 3 1 CSS CAP., X7R, 0.1μF, 50V, 10% 0603 AVX, 06035C104KAT2A 4 1 C15 CAP., X7R, 1μF, 50V, 10% 0805 AVX, 08055C105K 5 2 C7, C8 CAP., X7R, 0.1μF, 50V, 10% 0603 AVX, 06035C104K 6 1 CF CAP., X7R, 22pF, 50V, 10% 0603 AVX, 06035C220K 7 1 C11 CAP., NPO, 68pF, 50V, 10% 0603 AVX, 06035A680KAT2A 8 1 C10 CAP., X5R, 2.2μF, 16V, 10% 0603 TDK, C1608X5R1C225K 9 1 C24 CAP., X5R, 1μF, 16V, 10% 0603 AVX, 0603YD105KAT2A 10 4 C16, C17, C19, C20 CAP., X7R, 22μF, 16V, 20% 1210 AVX, 1210YC226MAT2A 11 2 C4, C22 CAP., X7R, 0.22μF, 16V, 20% 0603 AVX, 0603YC224MAT2A dc1881af 3 DEMO MANUAL DC1881A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER 12 3 C9, C25, C26 CAP., X7R, 10μF, 50V, 20% 1210 TDK, C3225X7S1H106M 13 1 C18 CAP., X5R, 10μF, 6.3V, 20% 1206 AVX, 12066D106MAT2A 14 4 D4-D7 SCHOTTKY REC., DFLS160, POWER DI-123 DIODE INC., DFLS160 15 1 D8 ZENER DIODE, 5.1V, BZX84C5V1, SOT23 DIODES INC., BZX84C5V1-7-F 16 1 L1 INDUCTOR, 5.6μH COILCRAFT, XAL7070-562ME 17 2 Q1, Q2 DUAL N-CHANNEL MOSFET, SO-8 VISHAY, Si4288DY-T1-E3 18 1 RC RES., CHIP, 13k, 1/10W, 1% 0603 VISHAY, CRCW060313K0FKEA 19 1 RFB1 RES., CHIP, 113k, 1/10W, 1% 0603 YAGEO, RC0603FR-07113KL 20 1 RFB2 RES., CHIP, 8.06k, 1/10W, 1% 0603 YAGEO, RC0603FR-078K06L 21 1 R18 SENSOR RES., 0.015Ω, 1W, 1%, 2512 THIN FILM TECH., RL3720WT-R015-F 22 1 R2 SENSOR RES., 0.015Ω, .25W, 1%, 1206 VISHAY, WSL1206R0150FEA 23 6 R3, R4, R9, R10, R13, R14 RES., CHIP, 100Ω, 1/10W, 1% 0603 YAGEO, RC0603FR-07100RL 24 1 R7 RES., CHIP, 100k, 1/10W, 1% 0603 YAGEO, RC0603FR-07100KL 25 1 R8 RES., CHIP, 10Ω, 1/10W, 5% 0603 YAGEO, RC0603JR-0710RL 26 1 R26 RES., CHIP, 10Ω 1/8W, 5% 0805 YAGEO, RC0805JR-0710RL 27 1 R5 RES., CHIP, 10Ω 1/8W, 5% 0805 YAGEO, RC0805JR-0710RL 28 6 R1, R11, R17, R23, R25, R27 RES., CHIP, 0Ω, 1/10W, 1% 0603 YAGEO, RC0603FR-070RL 29 1 R20 0Ω JUMPER, 1/4W, 1206 IRC 30 1 R16 RES., CHIP, 1k, 1/10W, 1% 0603 YAGEO, RC0603FR-071KL 31 1 R24 RES., CHIP, 10k, 1/10W, 1% 0603 YAGEO, RC0603FR-0710KL 32 1 R21 RES., CHIP, 121k, 1/10W, 1% 0603 YAGEO, RC0603FR-07121KL 33 1 R30 RES., CHIP, 41.2k, 1/10W, 1% 0603 YAGEO, RC0603FR-0741K2L 34 1 R31 RES., CHIP, 12.1k, 1/10W, 1% 0603 YAGEO, RC0603FR-0712K1L 35 1 U1 I.C., VOLT. REG. LINEAR TECH. CORP. LTC3789EUFD Additional Demo Board Circuit Components 1 0 CF1 (OPT) CAP., 0603 2 0 COUT1 (OPT) CAP., OS-CON, 330μF, 16V, 20% 3 0 C14, C23, C29 C35 (OPT) CAP., 1210 4 0 C12, C13 (OPT) CAP., 1206 5 0 R6, R12, R22 (OPT) RES., 0603 6 0 R28, R29 (OPT) RES., CHIP, 1206 SANYO, 16SEP330M+T Hardware: For Demo Board Only 1 2 JP1, JP2 3-PIN 0.079" SINGLE ROW HEADER SAMTEC, TMM103-02-L-S 2 2 XJP1, XJP2B SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G 3 9 TP3-TP7, TP10-TP14 TESTPOINT, TURRET, 0.094" pbf MILL-MAX, 2501-2-00-80-00-00-07-0 4 4 (STAND-OFF) STAND-OFF, NYLON 0.50" KEYSTONE, 8833 (SNAP ON) dc1881af 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 C D EXTVCC TP4 TP12 JP1 RUN 3 2 1 JP2 MODE 5 R31 12.1K 41.2K R30 VIN+ CCM RFB1 113K R24 10K D8 BZX84C5V1 3 2 1 INTVCC CF1 OPT RFB2 8.06K R16 1K CSS 0.1uF PULSE SKIP TP10 TP5 OFF ON PLLIN SS PGOOD R7 100K INTVCC R25 0 R22 OPT VOUT VIN+ C8 C7 121K R21 13K RC CC1 100 100 VOUT 0.01uF CC2 R10 R9 INTVCC CF 22pF VOS+ C11 68pF R14 100 50V R13 100 C24 1uF 16V 17 9 8 7 6 5 4 3 2 1 EXTVCC ILIM VOUTSNS VINSNS RUN FREQ MODE/PLLIN SGND ITH SENSE1- SENSE1+ SS VFB C10 2.2uF TG1 TRIM SW2 TG2 BOOST2 BG2 INTVCC BG1 PGND BOOST1 SW1 4 1. ALL RESISTORS ARE 0603. ALL CAPACITORS ARE 0603. NOTE: UNLESS OTHERWISE SPECIFIED R26 10 0805 0.1uF 0.1uF 50V 100pF 28 27 26 U1 LTC3789EUFD 25 PGOOD 4 IOSENSE+ 10 19 VIN IOSENSE- 11 SGND 29 0 100 INTVCC R27 10 R5 3 VIN+ R18 0.015 1W R1 0 R6 OPT C22 0.22uF 16V 6.3V D7 DFLS160 C18 10uF 4 Q1A Si4288DY C4 0.22uF 16V Q1B Si4288DY 2 R12 OPT D4 DFLS160 0 R17 0 R23 0 R11 R4 R3 100 12 13 14 15 16 18 20 21 22 24 23 C15 1uF 50V 0805 3 7 8 1 5 6 3 D5 DFLS160 XAL7070 L1 5.6uH C12 (OPT) 1206 R28 (OPT) 1206 R29 (OPT) C13 (OPT) D6 DFLS160 C17 C16 22uF 16V 1210 C14 (OPT) 1210 2 C29 C23 (OPT) 1210 2 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 0.25W R2 0.015 R20 0 __ ECO SCALE = NONE C26 10uF 50V 1210 1 + TP14 R8 10 VOS+ TP13 TP7 TP6 TP3 DATE 4-23-12 GND 12V / 2.5A MAX VOUT GND VIN 6V - 36V VIN+ CHARLIE Z. APPROVED DATE: N/A SIZE 1 LTC3789EUFD DEMO CIRCUIT 1881A Tuesday, May 15, 2012 IC NO. SHEET 1 OF 1 2 REV. HIGH EFFICIENCY COMPACT BUCK-BOOST CONVERTER 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only COUT1 OPT 16V VOUT PRODUCTION DESCRIPTION REVISION HISTORY TECHNOLOGY C19 C20 22uF 16V 1210 2 REV CHARLIE Z. TITLE: SCHEMATIC HZ APPROVALS 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. 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. CUSTOMER NOTICE 2 C35 (OPT) 1210 VOUT1 Q2B Si4288DY 4 Q2A Si4288DY C9 C25 10uF 50V 1210 5 6 3 7 8 1 5 A B C D DEMO MANUAL DC1881A SCHEMATIC DIAGRAM dc1881af 5 DEMO MANUAL DC1881A 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 dc1881af 6 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