DEMO MANUAL DC1891A LTC3862-2 Low Noise PolyPhase® SEPIC DC/DC Converter DESCRIPTION Demonstration circuit 1891A is a 2-phase high efficiency nonisolated SEPIC (single ended primary inductor converter) converter featuring the LTC®3862-2 switching controller. The DC1891A converts a 6V to 60V input to a 12V output and provides 6A of output current. The converter operates at 300kHz (600kHz output ripple) with efficiency around 90%. With a proper amount of airflow, the DC1891A converter can generate over 6A of output current. The DC1891A can be easily modified to generate output voltages in the range from 0.8V to 48V. Also, the DC1891A can be optimized for specific input voltages. The narrowing of input voltage range can increase the converter’s efficiency. Therefore, a narrow input voltage range is more desirable. The LTC3862-2 can be synchronized to an external clock of up to 400kHz. Please refer to LTC3862-2 data sheet for design details and applications information. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology, PolyPhase and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. PERFORMANCE SUMMARY Specifications are at TA = 25°C PARAMETER CONDITIONS VALUE Minimum Input Voltage IOUT = 0A to 6A 6V Maximum Input Voltage IOUT = 0A to 6A 60V VOUT VIN = 6V to 60V, IOUT = 0A to 6A 12V ±3% Typical Output Ripple VOUT VIN = 6V to 60V, IOUT = 0A to 6A 100mVP-P Nominal Switching Frequency 300kHz dc1891af 1 DEMO MANUAL DC1891A QUICK START PROCEDURE Demonstration circuit 1891A is easy to set up to evaluate the performance of the LTC3862-2 circuit. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 4.Once the proper output voltage is established, adjust the load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the VIN or VOUT and GND terminals. See Figure 2 for the proper scope probe technique. 5.The DC1891A is equipped with an input capacitor CIN4 that is optional and is used to help with filtering when the board is connected to the lab supply with long leads. The capacitor CIN4 can be removed if the input power source is close and has low source impedance. 1.With power off, connect the input power supply to VIN and GND. Make sure that the input power supply has sufficient current rating at minimum input voltage for the required output load. 2.Turn on the power at the input. NOTE: Make sure that the input voltage does not exceed 60V. 3.Check for the proper output voltage. VOUT = 12V, ±3%. If there is no output, temporarily disconnect the load to make sure that the load is not set too high. CHANGING THE OUTPUT VOLTAGE To set the output voltage lower or higher than 12V, change the bottom voltage divider resistor connected to the FB pin of U1 (see the Schematic Diagram). Also, check the MOSFET, output diode and capacitor voltage ratings if the output voltage is set higher than 12V. The optional Q5 circuit is used to get the circuit running. Once the circuit is running, the 12V output is used to bias U1 via D2. The start-up circuit Q5 is turned off by Q6 when VOUT gets to the level set by D3, R14 and R16 that activates Q6. Please contact the LTC factory for details. dc1891af 2 DEMO MANUAL DC1891A QUICK START PROCEDURE DC1891a F01 Figure 1. Proper Measurement Equipment Setup GND VIN DC1891a F02 Figure 2. Measuring Input or Output Ripple dc1891af 3 DEMO MANUAL DC1891A QUICK START PROCEDURE 92 VIN = 12V, VOUT = 12V IOUT = 1A 3A LOAD STEP 90 88 EFFICIENCY (%) 86 84 VOUT 200mV/DIV 82 80 78 76 6V INPUT 12V INPUT 24V INPUT 48V INPUT 74 72 70 0 1 2 3 4 IOUT (A) 5 6 7 IOUT 2A/DIV 500µs/DIV 8 DC1891a F03 Figure 3. Reducing the Input Voltage Range and Selecting More Optimal MOSFET, Diode and Inductor Can Optimize the Efficiency of DC1891A OUTPUT LOAD STEP RESPONSE The load step response of DC1891A is very fast even though a relatively small amount of output capacitance is present (188µF ceramic and 440µF electrolytic). The load step transients are shown in Figure 4. To improve load step response further or to reduce the output ripple, more output capacitance can be added. Low ESR output capacitors will have the greatest effect on reducing the ripple and load step transients. DC1891a F04 Figure 4. Fast Transient Response of DC1891A is Achieved with a Small Amount of Output Capacitance SOFT-START FUNCTION The DC1891A features a soft-start circuit that controls the inrush current and output voltage ramp at start-up. The capacitor CSS controls the start-up period. The start-up waveforms are shown in Figure 5. VIN = 12V, VOUT = 12V IOUT = 5A START-UP IIN 2A/DIV VOUT 2V/DIV 50ms/DIV DC1891a F05 Figure 5. The DC1891A Ramps the Output Slowly at Start-Up without Generating an Input Current Surge dc1891af 4 DEMO MANUAL DC1891A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 CC2 CAP, NPO 100pF, 25V, 5%, 0603 AVX 06033A101JAT2A 2 4 C3, C4, CSS, C5 CAP, X7R 0.01µF 25V 10% 0603 AVX 06033C103KAT2A 3 1 CC1 CAP, X5R 0.015µF 25V 10% 0603 AVX 06033D153KAT2A 4 1 C1 CAP, NPO 1000pF 25V 10% 0603 AVX 06033A102JAT2A 5 1 C2 CAP, X5R, 2.2µF, 25V, 10%, 0805 AVX 08053D225KAT2A 6 1 CIN4 CAP, 33µF, 63V SUN ELECT, 63HVH33MS 7 1 CU1 CAP, X7R 4.7µF 50V 10% 1206 MURATA GRM31CR71H475KA12L 8 7 CS1 TO CS4, CIN1 TO CIN3 CAP, X7S 4.7µF 100V 20% 1812 TDK C4532X7S2A475M 9 4 COUT1 TO COUT4 CAP, X7S 47µF 16V 20% 1812 TDK CKG45NX7S1C476M 10 2 COUT5, COUT6 CAP, 220µF 16V APXE UNITED CHEMI-CON APX160ARA221MHA0G 11 1 CF CAP, X7R 0.01µF 16V 10% 0603 AVX 0603YC103KAT2A 12 2 D3, D5 ZENER DIODE, SOD-323 NXP SEMI PDZ6.8B 13 1 D4 DIODE, SOD-523 NXP SEMI BAS516 14 2 D1, D2 SCHOTTKY RECTIFIER, TO-277A VISHAY V8P10-M3/86A 15 2 Q2, Q4 POWER MOSFET, PG-TDSON-8 INFINEON BSC060N10NS3G 16 1 Q5 PNP TRANSISTOR, SOT-23 NXP SEMI PBSS9110T 17 2 Q6, Q8 NPN TRANSISTOR, SOT-323 NXP SEMI PMST5550 18 1 Q7 NPN TRANSISTOR, SC-75 NXP SEMI BC847T 19 1 RC1 RES, CHIP 13.7k, 1% 0603 VISHAY CRCW060313K7FKEA 20 1 ROSC RES, CHIP 43.2k, 1% 0603 VISHAY CRCW060343K2FKED 21 2 R4, R10 RES, CHIP 10Ω 5% 0603 VISHAY CRCW060310R0JNEA 22 2 RF, R17 RES, CHIP 0Ω, Jumper 0603 VISHAY CRCW06030000Z0EA 23 1 R9 RES, CHIP 110k, 1% 0805 VISHAY CRCW0805110KFKEA 24 1 R1 RES, CHIP 12.4k, 1% 0603 VISHAY CRCW060312K4FKEA 25 1 R3 RES, CHIP 845k, 1% 0603 VISHAY CRCW0603845KFKEA 26 1 R11 RES, CHIP 249k, 1% 0603 VISHAY CRCW0603249KFKEA 27 2 R6, R8 RES, 0.005Ω, 1/2W, 1%, 2010 VISHAY WSL20105L000FEA 28 1 R12 RES, CHIP 33k, 1% 0603 VISHAY CRCW060333K0FKEA 29 1 R13 RES, CHIP 220k, 1% 0603 VISHAY CRCW0603220KFKEA 30 1 R14 RES, CHIP 56k, 1% 0603 VISHAY CRCW060356K0FKEA 31 2 R15, R16 RES, CHIP 10k, 1% 0603 VISHAY CRCW060310K0FKEA 32 1 R19 RES, CHIP 100k, 1% 0603 NIC NRC06F1003TRF 33 1 R20 RES, CHIP 180k, 1% 0603 VISHAY CRCW0603180KFKEA 34 2 T1,T2 COUPLED INDUCTOR, 6.8µH WÜRTH 7448709068 35 1 U1 PWM CONTROLLER LTC3862EFE-2 LINEAR TECHNOLOGY LTC3862EFE-2 dc1891af 5 DEMO MANUAL DC1891A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Additional Demo Board Circuit Components 1 0 Q1, Q3 (OPT) MOSFET, PG-TDSON-8 2 0 R18 (OPT) RES, CHIP 0603 3 0 R7, R5 (OPT) RES, CHIP 2010 Hardware: For Demo Board Only 1 6 E3 TO E8 TESTPOINT, TURRET, 0.094" MILL-MAX 2501-2-00-80-00-00-07-0 2 2 E1, E2 STUD, TEST PIN PEM KFH-032-10ET 3 4 E1, E2 (2 each) NUT BRASS, # 10-32 M/S BR PL ANY 10-32 4 2 E1, E2 RING, LUG # 10 KEYSTONE, 8205 5 2 E1, E2 WASHER #10, TIN PLATED BRASS ANY #10EXT BZ TN 6 4 JP1 TO JP4 HEARDER, 3PIN 1 ROW 0.079CC SULLINS NRPN031PAEN-RC 7 4 JP1 TO JP4 SHUNT, 0.079" CENTER SAMTEC 2SN-BK-G 8 1 SW1 SWITCHE, SEALED TOGGLE C&K GT11MCBE (THRU-HOLE) 9 4 STAND-OFF STAND-OFF, NYLON 0.50" TALL KEYSTONE 8833(SNAP ON) 10 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 1891A dc1891af 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 Q7 A BC847T 3 2 180° 120° 3 2 1 1 RC1 13.7k R19 100k C5 10nF 10nF R13 220k +VIN R16 10k 1 2 Q8 PMST5550 R12 33k R15 10k PBSS9110T Q5 PLLFLTR SYNC CLKOUT SGND FB ITH SS FREQ 3 SENSE2+ SENSE2- B NC G2 PGND G1 INTVCC VIN RUN SENSE1- SENSE1+ 3V8 JP4 DMAX U1 LTC3862EFE-2 PHASEMODE BLANK SLOPE DMAX JP3 SLOPE B Optional Bias Circuit PMST5550 1 Q6 R14 56k 12 11 VOUT P11 P10 9 8 7 6 5 4 3 2 1 10 1.66 1.0** 0.625 3 2 1 D3 PBZ6.8B Vu1 RF 0 R9 110k R1 12.4k CSS 43.2k JP2 BLANK ROSC 3 2 1 R20 180k CF 0.01uF CC2 100pF CC1 15nF JP1 PHASE 325ns 250ns** 175ns 1 2 4 3 2 3 75% 84%** 96% 3 2 1 GND 25 1 24 0 1 1nF Vu1 4.7uF 845k R4 10 CU1 R3 R11 249k C1 OFF ON CIN1 CIN2 CIN3 +VIN + C THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. D 2 CS1 47uF 16V 3 1 SCALE = NONE GORAN P. HZ 4.7uF 100V 4.7uF 100V D1 V8P10 1 4.7uF 100V E8 E7 E6 E5 E4 E3 E2 E1 +VIN 5-23-12 DATE 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only GND GND GND GND 12V / 6A Goran P. APPROVED E * See Demo Manual * * +VOUT GND 6V-60V TECHNOLOGY VOUT +VIN PRODUCTION DESCRIPTION REVISION HISTORY D DATE: N/A SIZE LTC3862EFE-2 DEMO CIRCUIT 1891A Wednesday, August 01, 2012 IC NO. E SHEET 1 OF 1 2 REV. LOW NOISE POLYPHASE SEPIC POWER CONVERTER TITLE: SCHEMATIC 2 REV 4.7uF 100V T1 7448709060 6.8uH 4 2 CS3 CS4 D2 V8P10 COUT1 COUT2 COUT3 COUT4 220uF 16V APXE Q3 OPT Q4 BSC060N10NS3G R7 OPT R8 .005 1W R6 .005 1W COUT5 COUT6 Q1 OPT CS2 Q2 BSC060N10NS3G R5 OPT __ ECO T2 7448709060 6.8uH 4 3 APPROVALS 4.7uF 100V R10 10 CIN4 33uF 63V HVH 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 OPT R17 1 R18 2 C4 10nF C2 2.2uF 3 1 C3 10nF PDZ6.8B D4 BAS516 13 14 15 16 17 18 19 20 21 22 23 2 D5 2 RUN SW1 C + 2 A 1 2 3 4 DEMO MANUAL DC1891A SCHEMATIC DIAGRAM dc1891af 7 DEMO MANUAL DC1891A 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 dc1891af 8 Linear Technology Corporation LT 0812 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2012