DEMO MANUAL DC1854A LT8471EFE Dual Output, Buck and Inverting Converter Description DC1854A is a dual output buck and inverting converter. It provides 5V and –5V power from 6V to 32V input. The 5V output can source up to 1.4A load current and the –5V output can source up to 800mA load current. See the load current versus input voltage figures inside this demo manual for more information. The internal skyhook supply is used to provide voltage to the internal npn switch and can be used for various topologies. Although they are assembled as a single inductor buck and a single inductor inverting converter on DC1854A, the two DC/DC converters can be altered for different topologies. The LT®8471 is a dual PWM DC/DC converter containing two internal 2A, 50V switches and an additional 500mA switch to facilitate step-down and inverting conversion. Each 2A channel can be independently configured as a buck, boost, SEPIC, flyback or inverting converter. Capable of generating positive and negative outputs from a single input rail, the LT8471 is ideal for many local power supply designs. Performance Summary PARAMETER The LT8471 has an adjustable oscillator, set by a resistor placed from the RT pin to ground. Additionally, the LT8471 can be synchronized to an external clock. The free running or synchronized switching frequency range of the part can be set between 100kHz and 2MHz. DC1854A is set at 450kHz. Additional features such as frequency foldback, soft-start, and power good are integrated. The LT8471 data sheet gives a complete description of the part, operation and applications information. The data sheet must be read in conjunction with this Demo Manual for DC1854A. The LT8471EFE is assembled in a 20-lead plastic TSSOP (FE) package with a thermally enhanced ground pad. Proper board layout is essential for maximum thermal performance. See the data sheet section Layout Considerations. Design files for this circuit board are available at http://www.linear.com/demo/DC1854A L, LT, LTC, LTM, 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 CONDITIONS MIN VIN Input Voltage Range TYP 6 to 32 450 MAX UNITS V Switching Frequency R1 = 187k VOUT1 R2 = 316k, R3 = 59k Maximum Load Current IOUT1 VIN = 6V VIN = 12V VIN = 28V VOUT2 R4 = 316k, R5 = 59k Maximum Load Current IOUT2 VIN = 6V VIN = 12V VIN = 28V Efficiency VIN = 12V, IOUT1 = 1.45A, IOUT2 = 840mA VOUT1 AC ripple VIN = 12V, IOUT1 = 1.45A 7 mVP-P VOUT2 AC ripple VIN = 12V, IOUT2 = 840mA 13 mVP-P 5 1.5 1.45 1.2 kHz V A A A –5 550 840 1 V mA mA A 80.6 % dc1854af 1 DEMO MANUAL DC1854A Quick Start Procedure DC1854A is easy to set up to evaluate the performance of the LT8471EFE Follow the procedure below: 3.Connect resistive or electronic loads within the maximum parameters to outputs VOUT1 and VOUT2. 1.Connect the OV/UV terminal to GND to disable switching during power supply startup. 4.Release the OV/UV-to-GND connection. 2.With power off, connect the input power supply to the VIN and GND terminals. Make sure that the VIN DC input voltage will not exceed 32V. 5.Observe the VOUT1 and VOUT2 voltages as well as the PG1 and PG2 voltages. Observe the circuit efficiency or other operation while the input voltage is between 6V and 32V. Figure 1. Test Procedure Setup Drawing for DC1854A dc1854af 2 DEMO MANUAL DC1854A 90 1.75 85 1.50 75 70 65 1.00 VOUT2 (–5V) 0.75 0.50 60 0.25 55 50 VOUT1 (5V) 1.25 IOUT MAX (A) EFFICIENCY (%) 80 5 10 15 20 VIN (V) 25 30 35 0 5 10 15 dc1854 F02 Figure 2. DC1854A Efficiency at IOUT1,2 Max vs VIN (see Figure 3) 20 VIN (V) 25 30 35 dc1854 F03 Figure 3. DC1854A CH1 and CH2 Maximum Load Current vs Input Voltage VOUT1 VOUT2 dc1854 F04 Figure 4. DC1854A Output Voltage Ripple 12VIN, IOUT1 = 1.45A, IOUT2 = 840mA (Bandwidth Limit Enabled) Figure 5. DC1854A Output Voltage Ripple Measurement Method dc1854af 3 DEMO MANUAL DC1854A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 2 C1, C2 CAP., X7R 0.47µF 50V 10% 1206 MURATA, GRM31MR71H474KA01L 2 3 C3, C4, C5 CAP., X5R 2.2µF 50V 10% 1206 MURATA, GRM31CR61H225KA88L 3 1 C6 CAP., X5R 1µF 50V 10% 1206 TDK, C3216X5R1H105K 2 rls 4 2 C7, C8 CAP., X7R 0.1µF 16V 10% 0603 MURATA, GRM188R71C104KA01D 5 4 C9, C10, C14, C17 CAP., X5R 47µF 10V 10% 1210 MURATA, GRM32ER61A476KE20L 6 1 D1 DIODE, SCHOTTKY 40V 2A POWERDI123 DIODES INC., DFLS240L-7 7 1 D2 DIODE, SCHOTTKY 60V 2.1A DO214AC VISHAY, VS-10MQ060NTRPBF 8 1 L1 INDUCTOR, 6.8µH 4020 WURTH ELECTRONIK, 74437324068 9 1 L2 INDUCTOR, 10µH 4020 WURTH ELECTRONIK, 74437324100 10 1 L3 INDUCTOR, 15µH ±20% WURTH ELECTRONIK, 744025150 11 1 R1 RES., CHIP 187k 0.1W 1% 0603 VISHAY, CRCW0603187KFKEA 12 2 R2, R4 RES., CHIP 316k 0.1W 1% 0603 VISHAY, CRCW0603316KFKEA 13 2 R3, R5 RES., CHIP 59k 0.1W 1% 0603 VISHAY, CRCW060359K0FKEA 14 1 U1 I.C., VOLTAGE REG. TSSOP20-FE/CB LINEAR TECH., LT8471EFE#PBF Additional Demo Board Circuit Components 1 0 C11, C12, C15, C16, C18, C19 (Opt) CAP., 1210 2 1 C13 CAP., ALUM 47µF 35V 10% 3 0 C20 CAP., 1206 4 0 C21, C22 CAP., 0603 5 0 D3 SCHOTTKY DIODE SOD-123 SUN ELECT., 35CE47AX 6 1 R6 RES., CHIP 499k 0.1W 1% 0603 7 0 R7, R11, R12 RES., 0603 VISHAY, CRCW0603499KFKEA 8 2 R8, R9 RES., CHIP 100k 0.1W 5% 0603 VISHAY, CRCW0603100KFKEA 9 1 R10 RES/JUMPER, CHIP 0Ω 0.25W 5A 0603 VISHAY, CRCW06030000Z0EA Hardware: For Demo Board Only 1 13 E1-E13 TURRET, TESTPOINT MILL MAX, 2501-2-00-80-00-00-07-0 2 4 MH1-MH4 STAND-OFF, NYLON 0.25" TALL KEYSTONE, 8831 (SNAP ON) dc1854af 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 SS2 SS1 PG2 PG1 E13 E2 E1 SYNC OV/UV GND VIN 6V to 32V 5 E9 E12 R9 100k R6 499k 1% C7 0.1µF 0603 15µH 744025150 SS1 PG2 PG1 OV/UV C3 SHOUT C8 0.1µF 0603 8 17 4 6 D3 (Opt) SOD‐123 13 14 ALL RESISTORS 0603. R7 (Opt) C6 1µF 50V 1206 L3 C5 2.2µF 50V 1206 C1 0.47µF 50V 1206 C2 0.47µF 50V 1206 3 4 C3 U1 LT8471EFE FB1 R1 187k 1% 450kHz 3 E1 FB2 E2 2.2µF 50V 1206 NOTE: UNLESS OTHERWISE SPECIFIED. R11 (Opt) R8 100k C20 (Opt) 1206 R10 0 Ohm C13 47µF 35V R12 (Opt) E5 E11 E4 + 15 4 3 VIN1 18 SYNC 9 SS2 VIN2 1 C1 20 C2 7 RT 10 11 GND 12 GND 21 GND GND 5 5 2 16 19 D1 DFLS240L‐7 6.8µH 74437324068 L1 L2 10µH 74437324100 D2 VS‐10MQ060NTRPBF C4 2.2µF 50V 1206 R3 59.0k 1% R2 316k 1% 2 C21 (Opt) 0603 C22 (Opt) 0603 C12 (Opt) 1210 R5 59.0k 1% R4 316k 1% C11 (Opt) 1210 2 C10 47µF 10V 1210 C9 47µF 10V 1210 C14 47µF 10V 1210 C17 47µF 10V 1210 C15 (Opt) 1210 C18 (Opt) 1210 1 SGND C16 (Opt) 1210 C19 (Opt) 1210 E10 E6 E3 E8 E7 * GND VOUT1 +5V 1.4A GND VOUT2 ‐ 5V ‐800mA *See Demo Manual 1 * A B C D DEMO MANUAL DC1854A Schematic Diagram dc1854af 5 DEMO MANUAL DC1854A 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 dc1854af 6 Linear Technology Corporation LT 0214 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2014