DEMO MANUAL DC1909A LT3840 60V Current Mode Step-Down DC/DC Converter with Accurate Current Limit Description Demonstration circuit 1909A is a 150kHz, 60V currentmode DC/DC step-down converter with accurate current limit featuring the LT®3840. The circuit operates from a VIN range of 4.5V to 60V, survives an 80V transient, and outputs 3.3V at 20A (66W). An integrated buck-boost switching regulator generates a 7.5V bias supply voltage for MOSFET gate drive and IC power to increase the overall efficiency by reducing the power loss. 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 Performance Summary loads. Continuous current mode will maintain a constant switching frequency regardless of the load current. The average current control loop regulates the maximum output current of the switching regulator. An Optional LDO circuit is provided on the bottom side of the board for programming the LT3840 current limit set point. This board is suitable for a wide range of automotive, telecom, industrial, and other applications. The LT3840 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this demo manual for DC1909A. Design files for this circuit board are available at http://www.linear.com/demo 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. Specifications are at TA = 25°C SYMBOL PARAMETER CONDITIONS MIN IOUT = 0A to 20A 3.168 TYP MAX VIN Input Voltage Range VOUT Output Voltage 60 V 3.3 3.432 V IOUT Maximum Output Current fSW Switching Frequency 150 20 21.2 kHz VOUT(P-P) Output Ripple 50 mV VREG Output Regulation Line and Load (4.5VIN to 60VIN, 0AOUT to 20AOUT) 0.15 % POUT/PIN Efficiency (See Figure 3) VIN = 12V, IOUT = 20A VIN = 24V, IOUT = 20A 91.3 90.5 % % 4.5 18.8 UNITS A dc1909af 1 DEMO MANUAL DC1909A Quick Start Procedure DC1909A is easy to set up to evaluate the performance of the LT3840. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 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 2 for the proper scope technique. 1.Set an input power supply that is capable of 60V/20A. Then turn off the supply. 2.With power off, connect the supply to the input terminals VIN and GND. a.Make the ENABLE jumper is in the EN position. b.Input voltages lower than 4.5V can keep the converter from turning on due to the undervoltage lockout feature of the LTC3840. c.If efficiency measurements are desired, an ammeter capable of measuring 20A DC or a resistor shunt can be put in series with the input supply in order to measure the DC1909A’s input current. d.A voltmeter with a capability of measuring at least 60V can be placed across the input terminals in order to get an accurate input voltage measurement. 3.Turn on the power at the input. NOTE: Make sure that the input voltage never exceeds 80V. 4.Check for the proper output voltage of 3.3V. Turn off the power at the input. 5.Once the proper output voltage is established, connect a variable load capable of sinking 20A at 3.3V to the output terminals VOUT and GND. Set the current for 0A. a.If efficiency measurements are desired, an ammeter or a resistor shunt that is capable of handling 20ADC can be put in series with the output load in order to measure the DC1909A’s output current. b.A voltmeter with a capability of measuring at least 3.3V can be placed across the output terminals in order to get an accurate output voltage measurement. 6.Turn on 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. dc1909af 2 DEMO MANUAL DC1909A Quick Start Procedure Figure 1. Proper Measurement Equipment Setup + VOUT – COUT GND Figure 2. Measuring Output Ripple dc1909af 3 DEMO MANUAL DC1909A Quick Start Procedure 95 EFFICIENCY (%) 90 85 80 75 VIN = 12V VIN = 24V 0 4 12 8 IOUT (A) 16 20 DC1909a F03 Figure 3. DC1909A Pulse-Skipping Mode Efficiency IOUT 5A/DIV VOUT 100mV/DIV 200µs/DIV DC1909a F04 Figure 4. DC1909A 9.5A to 19.5A Load Transient dc1909af 4 DEMO MANUAL DC1909A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Cap., SMT Alum 56µF 63V 25% Sun Elect.Ind. 63HVH56M Required Circuit Components 1 2 CIN1, CIN2 2 1 CIN3 Cap., X7S 0.22µF 100V 10% 0805 TDK C2012X7S2A224KT 3 6 CIN4 to CIN9 Cap., X7R 2.2µF 100V 20% 1210 Taiyo Yuden HMK325B7225MN-T 4 2 COUT1, COUT2 Cap., X5R 22µF 6.3V 20% 0805 TDK C2012X5R0J226M 5 2 COUT5, COUT6 Cap., POSCAP 680µF 6.3V ±20% D4 Panasonic 6TPE680MI 6 2 C1, C4 Cap., X7R 1µF 16V 10% 0603 TDK C1608X7R1C105K 7 1 C2 Cap., X5R 4.7µF 16V 20% 0603 TDK C1608X5R1C475MT 8 1 C3 Cap., X7R 0.47µF 100V 10% 1206 TDK C3216X7R2A474K 9 2 C6, C13 Cap., X7R 10nF 16V 20% 0402 AVX 0402YC103MAT2A 10 1 C8 Cap., NPO 100pF 25V 10% 0402 AVX 04023A101KAT2A 11 2 C10, C12 Cap., X7R 2.2nF 25V 20% 0402 AVX 04023C222MAT2A 12 1 C11 Cap., NPO 1nF 25V 10% 0402 AVX 04023A102KAT2A 13 1 C16 Cap., X7R 1µF 100V 15% 1206 Murata GRM31CR72A105KA01L 14 1 D1 Fast Switching Diode SOD-323 Diodes Inc. 1N4448HWS 15 1 D2 Schottky Diode 5A PowerDi5 Diodes Inc. PDS5100H 16 1 L1 Inductor, 33µH Coilcraft ME3320-333KL 17 1 L2 Inductor, 2.2µH COOPERBussmann HC2LP-2R2-R 18 2 Q1, Q2 MOSFET, N-Channel, 80V PG-TDSON-8 Infineon BSC123N08NS3 19 2 Q3, Q4 MOSFET, N-Channel, 75V/100A SuperSO8 Infineon BSC042NE7NS3 20 1 RSNS1 Res., 0.0025 1W 1% 2512 Vishay WSL25122L500FEA 21 5 R2, R7, R19, R20, R22 Res., Chip 0Ω 1/16W 1A 0402 Vishay CRCW04020000Z0ED 22 1 R3 Res., Chip 1M 0.06W 5% 0402 Vishay CRCW04021M00JNED 23 2 R6, R8 Res., Chip 12 0.06W 5% 0402 Vishay CRCW040212R0JNED 24 2 R9, R14 Res., Chip 100k 0.06W 5% 0402 Vishay CRCW0402100KJNED 25 1 R10 Res., Chip 825k 0.06W 1% 0402 Vishay CRCW0402825KFKED 26 1 R11 Res., Chip 105k 0.06W 1% 0402 Vishay CRCW0402105KFKED 27 1 R12 Res., Chip 13.0k 0.06W 1% 0402 Vishay CRCW040213K0FKED 28 1 R13 Res., Chip 499k 0.06W 1% 0402 Vishay CRCW0402499KFKED 29 1 R17 Res., Chip 1M 0.06W 5% 0603 Vishay CRCW06031M00JNEA 30 1 R21 Res., Chip 1k 0.06W 5% 0402 Vishay CRCW04021K00JNED 31 1 U1 I.C., LT3840EFE TSSOP28 Linear Technology Corporation LT3840EFE#PBF Additional Circuits 1 0 CIN10, CIN11, CIN12 (Opt) Cap., 1210 2 0 COUT3, COUT4 (Opt) Cap., 0805 3 0 COUT7 (Opt) Cap., 0603 4 0 C5 (Opt) Cap., 1206 5 0 C7, C9, C17 (Opt) Cap., 0402 6 0 C14 (Opt) Cap., X7R 1µF 16V 20% 0805 Taiyo Yuden EMK212BJ105MG 7 0 C15 (Opt) Cap., X7R 1µF 10V 10% 0603 Taiyo Yuden LMK107BJ105KA 8 0 R4 (Opt) Res., 1206 9 0 R5 (Opt) Res., 0402 dc1909af 5 DEMO MANUAL DC1909A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER 10 11 0 R15 (Opt) Res., Chip 3.74M 0.06W 1% 0603 Vishay CRCW06033M74FKEA 0 R16, R18 (Opt) Res., 0603 12 0 U2 (Opt) I.C., LDO Linear Reg. SC70-SC8 Linear Technology Corporation LT3009ESC8-5#PBF Hardware, For Demo Board Only: 1 11 E1, E2, E5, E6, E7, E8, E9, E10, Turret, Testpoint E11, E12, E13 Mill Max 2501-2-00-80-00-00-07-0 2 2 E3, E4 Turret, Testpoint Mill Max 2308-2-00-80-00-00-07-0 3 1 JP1 Headers, 3 Pins 2mm Ctrs. Sullins NRPN031PAEN-RC 4 1 JP2 Headers, Dbl. Row 2 × 3 2mm Ctrs. Sullins NRPN032PAEN-RC 5 6 J1, J2, J3, J4, J5, J6 Connector, Banana Jack Keystone 575-4 6 2 XJP1, XJP2 Shunt, 2mm Ctrs. Samtec 2SN-BK-G 7 4 MH1 to MH4 STANDOFF, NYLON, 0.5" KEYSTONE, 8833 (SNAP ON) dc1909af 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 VIN_S GND GND IMON ICTRL GND GND TK/SS SYNC PG E2 J2 J1 1 E13 E12 E11 E10 E9 E8 E7 E6 E5 JP1 3 2 ENABLE DIS EN GND_S GND VIN 4V TO 60V 80V TRANSIENT E1 5 ICTRL R14 100k R9 100k VOUT R17 1M 0603 4 6 3 5 JP2 2 1 MODE R7 0 Ohm R5 (Opt) R3 1M INTVCC FB 63V R18 (Opt) 0603 CIN2 63V + 56礔 CIN1 + 56礔 BURST C8 100pF C10 2.2nF R12 13.0k 1% C13 10nF 6 8 5 10 4 9 11 12 13 3 14 4 28 1礔 16V 0603 C11 1nF R21 1k AUXSW1 1 18 C17 (Opt) 17 ICTRL C12 2.2nF 29 GND R22 0 Ohm 16 IMON GND FB SENSE- SENSE+ BGRTN BG SW TG BOOST PGND INTVCC AUXSW2 27 L1 33礖 ME3320-333KL U1 LT3840EFE#PBF ICOMP TK/SS VC RT MODE SYNC PG OVLO UVLO EN AUXVIN VIN AUXBST NOTE: UNLESS OTHERWISE SPECIFIED. 1. ALL RESISTORS 0402. 2. ALL CAPACITORS 0402. CONT PULSE SKIP R11 105k 1% (150kHz) 1206 1uF 100V C16 0.47uF 100V 1206 C3 C1 15 7 20 19 24 25 21 22 23 2 26 C7 (Opt) C6 10nF 3 C4 12 R6 (Opt) C9 825k 1% R10 BSC042NE7NS3 1礔 16V 0603 Q3 Q1 BSC123N08NS3 D1 1N4448HWS R13 499k 1% 12 R8 0 Ohm R20 R19 0 Ohm R2 C2 4.7礔 16V 0603 0 Ohm FB INTVCC 3 Q4 BSC042NE7NS3 C5 (Opt) 1206 R4 (Opt) 1206 Q2 BSC123N08NS3 CIN3 0.22uF 100V 0805 CIN5 2.2uF 100V 1210 2 CIN6 2.2uF 100V 1210 D2 PDS5100H 2 0.0025 1% 1W 2512 L2 2.2礖 HC2LP-2R2-R COOPERBussmann RSNS1 CIN4 2.2uF 100V 1210 2 D 4 3 1 5 COUT1 22uF 6.3V 0805 CIN8 2.2uF 100V 1210 C14 1uF 16V 0805 INTVCC CIN7 2.2uF 100V 1210 1 5 CIN10 (Opt) 1210 ADJ OUT 2 3 4 GND GND GND SHDN IN 7 6 U2 LT3009ESC8-5#PBF VOUT COUT4 COUT5 COUT6 (Opt) + 680礔 + 680礔 6.3V 6.3V 0805 CIN12 (Opt) 1210 COUT3 (Opt) 0805 CIN11 (Opt) 1210 C15 1uF 10V 0603 5V R16 TBD 0603 1 R15 3.74M 1% 0603 ICTRL OPTIONAL CIRCUIT COUT2 22uF 6.3V 0805 CIN9 2.2uF 100V 1210 1 E4 J6 J5 GND_S GND VOUT 3.3V / 20A VOUT_S COUT7 0603 J4 J3 E3 A B C D DEMO MANUAL DC1909A Schematic Diagram dc1909af 7 DEMO MANUAL DC1909A 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 dc1909af 8 Linear Technology Corporation LT 0614 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2014