DEMO MANUAL DC1619A LT3845A: High Voltage Synchronous Buck Controller with Programmable Frequency and Sync DESCRIPTION Demonstration Circuit 1619A is a 100kHz to 500kHz programmable frequency, high voltage, current mode DC/DC step-down converter featuring the LT®3845A. The operating frequency can be synchronized up to 600kHz. This demo board is designed for 12V up to 10A (120W) output from a 16V to 60V input. A soft-start feature controls the output voltage slew rate at start-up, reducing current surges and voltage overshoots. The modes of operation (Burst Mode®, discontinuous current mode and continuous current mode) are jumper selectable. Both Burst Mode operation and discontinuous current mode increase the efficiency at light loads. Continuous current mode will maintain a constant switching frequency regardless of the load current. output voltages. In such applications, this optional circuit can increase the overall efficiency by reducing the power loss in the LT3845A. The demonstration board has the option of doubling the number of switching MOSFETs to facilitate higher output current. This board is suitable for a wide range of industrial control systems and telecom power supplies. An optional boost bias circuit is provided on the bottom side of the board for back-driving the LT3845A internal regulator from the output voltage. Customers may want to use this optional circuit with modified applications that have relatively high input voltages and low (~3.3V) Design files for this circuit board are available at http://www.linear.com/demo PERFORMANCE SUMMARY PARAMETER FOR BUCK REGULATOR The LT3845A data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this quick start guide for demo circuit 1619A. Note: It is best to ground the SYNC pin if the SYNC function is not being used. L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. (TA = 25°C) CONDITION VALUE Minimum Input Voltage 16V Maximum Input Voltage 60V Output Voltage, VOUT 12V ±2% Maximum Output Current VIN < 28V VIN ≥ 28V 7.5A to 10A (See Figure 5) 10A Typical Switching Frequency R9 = 49.9k 300kHz External Clock Synchronous Frequency Range R9 = 49.9k 325kHz to 600kHz Efficiency VIN = 48V, VOUT = 12V, IOUT = 8A 94% (See Figure 3) dc1619af 1 DEMO MANUAL DC1619A QUICK START PROCEDURE Demonstration circuit 1619A is easy to set up to evaluate the performance of the LT3845A. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 4. Turn on the power at the input and adjust the input voltage until the LT3845A turns on. 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 directly across the VIN or VOUT capacitors by soldering leads on the appropriate capacitor. See Figure 2 for proper scope probe technique. An oscilloscope probe can be directly connected to VIN or VOUT using a banana jack to BNC adaptors. 5. Check for the proper output voltage. 1. Place JP1 in the RUN position. 2. Place JP2 in the desired operating mode: burst, pulseskipping or continuous. 3. With power off, connect the input power supply to VIN and GND. – V + Note: Make sure that the input voltage does not exceed 60V. Note: If output does not come up, make sure the load is not set too high. Reduce the load and repeat steps 4 and 5. 6. Once the proper output voltage is established, adjust the input voltage and load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. 7. An external clock can be added to the SYNC pin when the SYNC function is used. See the Oscillator SYNC section in the data sheet for details. – – 0V TO 60V 7.5A + + LOAD 0A TO 10A A – – A + + – V + DC1619 F01 Figure 1. Proper Measurement Equipment Setup dc1619af 2 DEMO MANUAL DC1619A QUICK START PROCEDURE WIRE INPUT OR OUTPUT CAPACITOR Figure 2. Measuring Input or Output Ripple 100 95 EFFICIENCY (%) 90 85 80 75 70 16VIN 20VIN 24VIN 36VIN 48VIN 60VIN 65 60 55 50 0 1 2 3 4 5 6 IOUT (A) 7 8 9 10 DC1619A F03 Figure 3. DC1619A Burst Mode Efficiency dc1619af 3 DEMO MANUAL DC1619A QUICK START PROCEDURE Figure 4. DC1619A 2A to 8A Load Transient 10.5 IOUT(MAX) (A) 10.0 9.5 9.0 8.5 8.0 7.5 16 20 24 28 32 36 40 44 48 52 56 60 VIN (V) DC1619A F05 Figure 5. DC1619A Output Current Derating Graph dc1619af 4 DEMO MANUAL DC1619A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 2 CIN1, CIN2 CAP., SMT Aluminum, 33μF, 63V SUNCON, 63HVH33M 2 2 CIN3, CIN4 CAP., X7R, 2.2μF, 100V, 10%, 1210 MURATA,GRM32ER72A225KA35L 3 1 COUT1 CAP., POSCAP, 68μF, 16V, 20%, SANYO, 16TQC68M 4 1 COUT3 CAP., X5R, 22μF, 16V, 10%, 1210 TAIYO, EMK325BJ226KM-T 5 1 C1 CAP., X5R, 0.47μF, 100V, 10%, 1206 TDK, C3216X5R2A474KAT 6 2 C2, C5 CAP., X7R, 1500pF, 50V, 10%, 0402 AVX, 04025C152KAT 7 1 C4 CAP., C0G, 100pF, 50V, 10%, 0402 TDK, C1005COG1H101J 8 1 C6 CAP., X5R, 0.1μF, 16V, 10%, 0402 AVX, 0402YD104KAT 9 1 C7 CAP., X5R, 1μF, 16V, 10%, 0603 TDK, C1608X5R1C105K 10 1 C9 CAP., C0G, 220pF, 100V, 10%, 1206 VISHAY, VJ1206A221XB 11 1 D1 HIGH VOLTAGE SWITCHING DIODE, SOD-523 PHILLIPS, BAS521 12 1 D2 SMT SCHOTTKY BARRIER RECTIFIER, SMB DIODES INC, B160-13-F 13 1 D3 HIGH VOLTAGE SWITCHING DIODE, SOD-323 DIODES INC, 1N4148WS-7-F 14 1 L1 INDUCTOR, 10μH WURTH ELEKTRONIC, 74435561100 15 2 Q1, Q2 N-MOSFET, 80V INFINEON, BSC123N08NS3 16 1 R1 RES., CHIP, 1M, 1/16W, 1%, 0402 VISHAY, CRCW04021M00FKED 17 1 R2 RES., CHIP, 97.6k, 1/16W, 1%, 0402 VISHAY, CRW040297K6FKED 18 1 R4 RES., CHIP, 143k, 1/16W, 1%, 0402 VISHAY, CRCW0402143KFKED 19 1 R5 RES., CHIP, 16.2k, 1/16W, 1%, 0402 VISHAY,CRCW040216K2FKED 20 1 R7 RES., CHIP, 20k, 1/16W, 1%, 0402 VISHAY, CRCW040220K0FKED 21 1 R9 RES., CHIP, 49.9k, 1/16W, 1%, 0402 VISHAY,CRCW040249K9FKED 22 1 R10 RES., CHIP, 4.99Ω, 1/16W, 1%, 0402 VISHAY,CRCW04024R99FKED 23 1 R16 RES., CHIP, 6.65Ω, 1/4W, 1%, 1206 VISHAY, CRCW12066R65FKED 24 1 R17 RES., CHIP, 0.007Ω, 1W, 1%, 2512 VISHAY, WSL25127L000FEA 25 1 U1 I.C, LT3845AEFE#PBF, TSSOP (4.4MM) 16-PIN LINEAR TECH., LT3845AEFE#PBF Additional Demo Board Circuit Components 1 0 COUT2 (OPT) CAP., POSCAP, 68μF, 16V, 20%, SANYO, 16TQC68M 2 0 COUT4 (OPT) CAP., X5R, 22μF, 16V, 10%, 1210 AVX, 1210YD226KAT 3 0 C3, C8, C10-C13 (OPT) CAP., 0402 4 0 D4, D5 (OPT) DUAL SMT SWITCHING DIODE, SOT-23 DIODES INC, BAV99-7-F 5 1 R3 RES., CHIP, 5.1M, 1/16W, 5%, 0402 PANASONIC, ERJ2GEJ515X 6 5 R11-R15 RES., CHIP, 0Ω, 1/16W, 0402 VISHAY, CRCW04020000Z0ED 7 1 R8 RES., CHIP, 100k, 1/16W, 1%, 0402 VISHAY, CRCW0402100KFKED 8 0 Q4, Q5 (OPT) N-MOSFET, 80V INFINEON, BSC123N08NS3 9 0 Q3 (OPT) COMPLIMENARY MOSFET PAIR, SC-70 VISHAY, Si1555DL-T1-E3 10 0 R6, R18-R22 (OPT) RES., 0402 Hardware For Demo Board Only 1 4 J1-J4 JACK, BANANA KEYSTONE, 575-4 2 5 E1-E5 TESTPOINT, TURRET, 0.095" MILL-MAX, 2501-2-00-80-00-00-07-0 3 1 JP1 JMP, 3-PIN 1 ROW 0.079CC SAMTEC, TMM-103-02-L-S 4 1 JP2 2MM DOUBLE ROW HEADER 2x3 SAMTEC, TMM-103-02-L-D 5 2 JP1(1 and 2), JP2 (5 and 6) SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G 6 4 STAND-OFF STAND-OFF, NYLON 0.50" tall KEYSTONE, 8833(SNAP ON) dc1619af 5 B A E2 J1 J2 SYNC E3 6 BURST 5 CIN2 33uF 63V* CIN3 2.2uF 100V 1210 R3 5.1M 5% R6 R5 16.2K 1% R4 1% (OPT) VFB * 79V CAPACITOR SURGE VOLTAGE CIN1 + 33uF 63V* PULSE SKIP 4 3 VFB 2 1 CONT . + VCC JP2 MODE GND GND VIN 16V - 60V E1 143K (OPT) C3 SHDN RUN CIN4 2.2uF 100V 1210 R7 20K 1 R8 100K U1 8 FSET 7 SYNC 6 VC 5 VFB 4 BURST_EN 3 SS 2 SHDN 1 VIN R9 49.9K 1500pF C2 100V 1206 C1 0.47uF C4 100pF R2 97.6K C5 1500pF 2 JP1 R1 1M LT3845AEFE 17 SGND VIN 1 3 SENSE- 9 SENSE+ 10 PGND 11 BG 12 VCC 13 SW 14 TG 15 BOOST 16 0 R11 TG 4.99 R10 D3 1N4148 0 C8 (OPT) R13 16V BG VCC D1 BAS521 R12 C6 0.1uF 0 4 VCC C7 1uF 16V 0603 BG TG 4 8 7 6 5 1 2 3 8 7 6 5 6 R15 R14 1 2 3 1 0 0 C9 220pF 100V 1206 R16 6.65 1206 L1 D2 B160 10uH* VS+ 0.007 2512 R17 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL 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 + 2 - COUT1 + 68uF 16V REV ECO DESCRIPTION DATE GND GND VOUT 12V, 120W VOUT 11-15-10 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only E5 J3 J4 E4 VOUT MARTY M. APPROVED DATE: N/A SIZE 11-15-10 IC NO. LT3845AEFE DEMO CIRCUIT 1619A SHEET 1 OF 2 2 REV. HIGH VOLTAGE SYNCHRONOUS BUCK CONTROLLER WITH ADJUSTABLE OPERATING FREQUENCY TECHNOLOGY COUT3 22uF 16V 1210 VOUT COUT4 (OPT) 1210 REVISION HISTORY PRODUCTION FAB COUT2 (OPT) NC MARTY M. TITLE: SCHEMATIC SCALE = NONE APP ENG. PCB DES. APPROVALS * L1 LAYOUT PADS ARE NON-STANDARD PADS DESIGNED TO ACCOMMODATE THE WURTH ELEKTRONIC, 74435561100 INDUCTOR OR THE WURTH ELEKTRONIC, 7443551151 INDUCTOR NOTES:UNLESS OTHERWISE SPECIFIED RESISTORS: OHMS, 0402 CAPACITORS: uF, 0402 Q2 BSC123N08N SW Q1 BSC123N08N VIN 2 B A DEMO MANUAL DC1619A SCHEMATIC DIAGRAM dc1619af B A C10 1uF 10V R18 2 D4 BAV99 C11 1uF 10V 1 2VOUT 3VOUT C12 1uF 10V 2 R19 D5 BAV99 1 C13 1 REFER TO THE LT3845AEFE DATASHEET FOR MORE DETAILS. USE OPTIONAL BIAS CIRCUIT TO BACKFEED VCC WHEN VOUT IS BETWEEN 3V AND 9V AND VCC POWER DISSIPATION EXCEEDS 250mW. VCC 3 1uF 10V OPTIONAL BIAS CIRCUIT 3 4 3 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. 2 R20 BG CUSTOMER NOTICE Q3A Si1555DL 5 Q3B Si1555DL VOUT THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. 1 MARTY M. TITLE: SCHEMATIC TECHNOLOGY 4 4 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only Q5 Q4 IC NO. 2 DATE: 11-15-10 N/A SIZE LT3845AEFE DEMO CIRCUIT 1619A SHEET 2 OF 2 2 REV. HIGH VOLTAGE SYNCHRONOUS BUCK CONTROLLER WITH ADJUSTABLE OPERATING FREQUENCY NC PCB DES. SCALE = NONE R21 R22 APP ENG. APPROVALS BG SW TG VIN OPTIONAL POWER FETS 2 8 7 6 5 1 2 3 8 7 6 5 1 2 3 1 B A DEMO MANUAL DC1619A SCHEMATIC DIAGRAM dc1619af 7 DEMO MANUAL DC1619A 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 dc1619af 8 Linear Technology Corporation LT 0211 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2011