DEMO MANUAL DC1585A LT3083 Adjustable 3A Single Resistor Low Dropout Regulator DESCRIPTION Demonstration circuit 1585A is an adjustable 3A linear regulator featuring LT3083. Architected as a precision current source and voltage follower, it allows this new regulator to be used in many applications requiring high current, adjustability to zero output, and no heat sink. Also the device brings out the collector of the pass transistor to allow low dropout operation when used with multiple supplies. A key feature of the LT3083 is the capability to supply a wide output voltage range. DC1585A can be set to 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5.0V, as well as user selectable. DC1585A is capable of delivering up to 3A output current. DC1585A can be used as a high current linear regulator, a post regulator for switching supplies, a variable voltage supply or low output voltage power supply. PERFORMANCE SUMMARY Internal protection circuitry includes current limiting and thermal limiting. LT3083 regulator is offered in a 16-lead TSSOP (with an exposed pad for better thermal characteristics), a 4mm × 4mm DFN, 5-lead TO-220 and a 5-lead DD-PAK version. The LT3083 datasheet gives a complete description of the part, operation and application information. The datasheet should be read in conjunction with this quick start guide for working on or modifying the demo circuit 1585A. Design files for this circuit board are available at http://www.linear.com/demo 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 SYMBOL PARAMETER CONDITIONS MIN VIN Input Supply Range VOUT = 1.2V, IOUT1 = 1mA 1.7 TYP MAX 23 UNITS V VCONTROL VCONTROL Voltage VOUT = 1.2V, IOUT1 = 1mA 2.8 25 V VOUT Output Voltage Shunt at 1, 2 for JP1 1.14 1.2 1.26 V Shunt at 3, 4 for JP1 1.425 1.5 1.575 V Shunt at 5, 6 for JP1 1.71 1.8 1.89 V Shunt at 7, 8 for JP1 2.375 2.5 2.625 V Shunt at 9, 10 for JP1 3.201 3.3 3.399 V Shunt at 11, 12 for JP1 4.85 5.0 5.15 V dc1585af 1 DEMO MANUAL DC1585A QUICK START PROCEDURE Demonstration circuit 1585A is easy to set up to evaluate the performance of the LT3083. Refer to Figure 1 for the 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. Measure the input or output voltage ripple by touching the probe tip directly across the terminals of the input or output capacitors. See Figure 2 for the proper scope probe technique. 1. Use JP1 to set the desired output voltage. 2. With power off, connect the bias power supply to VCONTROL and GND. 5. Turn on the power at VIN. NOTE. Make sure that the VIN voltage does not exceed 23V. 6. Check for the proper output voltages. NOTE. If there is no output, temporarily disconnect the load to make sure that the load is not set too high or is shorted. 7. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, efficiency and other parameters. NOTE. Make sure that the power dissipation is limited below the thermal limit. 3. With power off, connect the input power supply to VIN and GND. 4. Turn on the power at VCONTROL. NOTE. Make sure that the VCONTROL voltage does not exceed 25V. + + – LOAD – + – – POWER SUPPLY + + – – – + – – + + POWER SUPPLY + Figure 1. DC1585A Proper Equipment Setup dc1585af 2 DEMO MANUAL DC1585A QUICK START PROCEDURE GND VIN Figure 2. Measuring Input or Output Ripple THERMAL IMAGE An example thermal image shows the temperature distribution on the board. The test is done in still air at room temperature with 6.4W power dissipation in the LT3083. This gives the IC case-to-ambient thermal resistance θJA=7.3°C/W on the demo board. Figure 3. Temperature Rise at 6.4W Dissipation dc1585af 3 DEMO MANUAL DC1585A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 2 C1, C2 CAP., X5R 4.7μF 50V 10% 1206 TAIYO YUDEN UMK316BJ475KLT 2 1 C3 CAP., X5R 22μF 16V 10% 1206 AVX 1206YD226KAT2A 3 1 C4 CAP., X7R 0.01μF 16V 10% 0603 AVX 0603YC103KAT2A 4 1 R1 RES., CHIP 24.3k 1/10W 1% 0603 VISHAY CRCW060324K3FKEA 5 1 R2 RES., CHIP 35.7k 1/10W 1% 0603 VISHAY CRCW060335K7FKEA 6 1 R3 RES., CHIP 49.9k 1/10W 1% 0603 VISHAY CRCW060349K9FKEA 7 1 R4 RES., CHIP 66.5k 1/10W 1% 0603 VISHAY CRCW060366K5FKEA 8 1 R5 RES., CHIP 100k 1/10W 1% 0603 VISHAY CRCW0603100KFKEA 9 1 R7 RES., CHIP 499 1/10W 1% 0805 VISHAY CRCW0805499RFKEA 10 1 R8 RES., CHIP 30.1k 1/10W 1% 0603 VISHAY CRCW06030K1FKEA 11 1 U1 I.C., LT3083EQ Q PACKAGE LINEAR TECH. CORP. LT3083EQ#PBF Additional Demo Board Circuit Components 1 1 CIN CAP., ALUMINUM. 10μF 50V 10% 2 0 R6(OPT) RES., 0603 SANYO 63CE22BS Hardware-For Demo Board Only: 1 5 E1-E5 TESTPOINT, TURRET, .095" MILL MAX 2501-2-00-80-00-00-07-0 2 1 JP1 2mm DOUBLE ROW HEADER, 2 × 7 PIN SAMTEC TMM-107-02-L-D 3 1 XJP1 SHUNT SAMTEC 2SN-BK-G dc1585af 4 B A VIN E3 E2 E1 + CIN * 10uF 50V * C2 4.7uF 50V 1206 C1 4.7uF 50V 1206 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 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. C4 0.01uF EDWIN L. APP ENG. SCALE = NONE HZ PCB DES. APPROVALS 13 11 10 3.3V 12 5.0V 9 R5 R1 R7 499 0805 E5 E4 DATE 02-02-10 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only EDWIN L. APPROVED DATE: N/A SIZE LT3083EQ DEMO CIRCUIT 1585A 2 Tuesday, November 09, 2010 IC NO. SHEET 1 OF 1 2 REV. ADJUSTABLE 3A SINGLE RESISTOR LDO REGULATOR TITLE: SCHEMATIC (OPT) 66.5K 1% R6 GND VOUT ADJ., 3A MAX 2nd PROTOTYPE DESCRIPTION REVISION HISTORY TECHNOLOGY 14 USER 100K 1% SELECT 2.5V 8 1.8V 6 7 4 3 R8 C3 22uF 16V 10% 1206 2 REV 2 24.3K 1% R2 30.1K 1% R3 35.7K 1% R4 49.9K 1% __ ECO 1.2V 1.5V 5 2 JP1 NC 1 OUT 6 OUT 3 1 LT3083EQ 4 VCONTROL 5 IN CUSTOMER NOTICE CIN IS OPTIONAL, FOR VIN PAMPING PURPOSE ONLY. 2. INSTALL SHUNTS AS SHOWN. 1. ALL RESISTORS AND CAPACITORS ARE IN 0603. NOTE: UNLESS OTHERWISE SPECIFIED GND VCONTROL 2.8V - 25V 1.7V - 23V U1 SET 2 1 B A DEMO MANUAL DC1585A SCHEMATIC DIAGRAM dc1585af 5 DEMO MANUAL DC1585A 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 dc1585af 6 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