DEMO MANUAL DC1948A LT3090 –36V, 600mA Negative Linear Regulator with Programmable Current Limit Description Demonstration circuit 1948A is a 600mA low dropout negative linear regulator featuring the LT®3090. This device is designed for applications requiring negative output voltage, high current with no heat sink, output adjustability to zero and low dropout voltage. The LT3090 features fast transient response, high PSRR and low output noise. The LT3090 supplies 600mA at a typical dropout voltage of 300mV. Operating quiescent current is nominally 1mA and drops to << 1μA in shutdown. A single resistor adjusts the LT3090’s precision programmable current limit. The LT3090’s positive or negative current monitor either sources a current (0.5mA/A) or sinks a current (1mA/A) proportional to output current. Built-in protection includes reverse output protection, internal current limit with foldback and thermal shutdown with hysteresis. The LT3090 is offered in a 10 pin DFN package and a 16-lead MSOP package. The LT3090 data sheet gives a complete description of the device, operation and application information. The data sheet should be read in conjunction with this quick start guide for working on or modifying the demo circuit 1948A. Design files for this circuit board are available at http://www.linear.com/demo/DC1948A 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. Performance Summary SYMBOL PARAMETER Specifications are at TA = 25°C CONDITIONS MIN TYP MAX UNITS VIN Input Supply Range VOUT = 1.2V, IOUT1 = 1mA –1.5 V VOUT Output Voltage Shunt at 1, 2 for JP1 –1.286 –1.25 –1.213 V Shunt at 3, 4 for JP1 –2.575 –2.5 –2.425 V IOUT Output Current –36 Shunt at 5, 6 for JP1 –5.15 –5 –4.85 V Shunt at 7, 8 for JP1 –12.36 –12 –11.64 V Shunt at 9, 10 for JP1 –15.45 –15 –14.55 V Shunt at 11, 12 for JP1 and R10 Stuffed as 357kΩ –18.54 –18 –17.46 V R1 = 10k, (Note 1) 600 mA Note 1. This is for the typical condition when VIN – VOUT < 5V. Current limit varies with different values of VIN – VOUT. Refer to the LT3090 data sheet for details. dc1948af 1 DEMO MANUAL DC1948A Quick Start Procedure Demonstration circuit 1948A is easy to set up to evaluate the performance of the LT3090. 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. 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 proper scope probe technique. 1.Use JP2 to set the desired output voltage. 2.Put JP4 on ON position. 3.With power off, connect the input power supply to VIN and GND. 4.Turn on the power at the VIN. NOTE. Make sure that the VIN voltage does not exceed –36V. 5.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. 6.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. Figure 1. DC1948A Proper Equipment Setup Figure 2. Measuring Input or Output Ripple dc1948af 2 DEMO MANUAL DC1948A Positive or Negative Current Monitor Configuration There are both positive and negative current monitors on the LT3090. The configurations for these two monitors are different. When the positive current monitor is in use, JP1 needs to be configured on IMP position and JP3 needs to be configured on +3V position. Meantime a +3V external power supply needs to be connected to +3V turret. Figure 3 shows this configuration. When the negative current monitor is in use, JP1 needs to be configured on VIN position and JP3 needs to be configured on IMN position. There is no external power supply needed. Figure 4 shows this configuration. Figure 4. Negative Current Monitor Configuration Figure 3. Positive Current Monitor Configuration Cable Drop Compensation Configuration Demo Circuit 1948A can be configured to evaluate the cable drop compensation on the LT3090. Note that cable drop compensation is only using negative current monitor configuration. JP1, JP3 and R12 shall be configured. JP1 needs to be configured on VIN position. JP3 needs to be configured on CDC position. R12 needs be replaced by a calculated value which has the following relationship with the total output cable impedance (RCBL) below. R12 and RCBL are both in kΩ: R12 = RCBL • 1k Thermal Image An example thermal image shows the temperature distribution on board. The test is complete in still air at room temperature with 2.1W power dissipation in the LT3090. This gives the IC case-to-ambient thermal resistance of about θJA = 24°C/W on the demo board. Figure 5. Temperature Rise at 2.1W Dissipation dc1948af 3 DEMO MANUAL DC1948A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 2 C1, CIN2 CAP, X7R 4.7µF 50V 10% 1206 TDK C3216X7R1H475KT 2 1 C2 CAP, X7R 0.1µF 16V 10% 0603 AVX 0603YC104KAT2A 3 1 C4 CAP, X7R 1µF 10V 10% 0603 TAIYO YUDEN LMK107BJ105KA 4 1 R1 RES, CHIP 10k 0.1W 1% 0805 VISHAY CRCW080510K0FKTA 5 1 R2 RES, CHIP 49.9k 0.1W 1% 0805 VISHAY CRCW080549K9FKTA 6 1 R4 RES, CHIP 2k 0.06W 1% 0603 VISHAY CRCW06032K00FKEA 7 1 R5 RES, CHIP 24.9k 0.06W 1% 0603 VISHAY CRCW060324K9FKEA 8 1 R6 RES, CHIP 49.9k 0.06W 1% 0603 VISHAY CRCW060349K9FKEA 9 1 R7 RES, CHIP 100k 0.06W 1% 0603 VISHAY CRCW0603100KFKEA 10 1 R8 RES, CHIP 243k 0.06W 1% 0603 VISHAY CRCW0603243KFKEA 11 1 R9 RES, CHIP 301k 0.06W 1% 0603 VISHAY CRCW0603301KFKEA 12 1 R11 RES, CHIP 1k 0.06W 1% 0603 VISHAY CRCW06031K00FKEA 13 1 R12, R14 RES, CHIP 0Ω 0.25W 5A 0603 VISHAY CRCW06030000Z0EA 14 1 U1 IC, NEGATIVE LINEAR REG DFN(10) (DD) 3mm × 3mm LINEAR TECHNOLOGY CORPORATION LT3090EDD Additional Demo Board Circuit Components 1 1 CIN1 CAP, ALUM 10µF 50V 10% 2 0 C3 (OPT) CAP, 1206 3 0 R10, R13, R15 (OPT) RES, 0603 SUNCON 50CE10BSS Hardware: For Demo Board Only 1 8 E1, E2, E3, E4, E6, E7, E8, E9 TURRET, TESTPOINT MILL MAX 2501-2-00-80-00-00-07-0 2 1 JP1 HEADERS, DBL ROW 2 × 2 2mm CTRS SAMTEC TMM-102-02-L-D 3 1 JP2 HEADERS, DBL ROW 2 × 6 2mm CTRS SAMTEC TMM-106-02-L-D 4 1 JP3 HEADERS, DBL ROW 2 × 3 2mm CTRS SAMTEC TMM-103-02-L-D 5 1 JP4 HEADERS, 2mm CTRS SAMTEC ASP-157349-01 6 4 XJP1, XJP2, XJP3, XJP4 SHUNT, 2mm CTRS SAMTEC 2SN-BK-G dc1948af 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 5 +3V IMONN IMONP SHDN GND + 5 4 3 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. SCALE = NONE EDWIN LI GND VOUT -600mA Max DATE Aug 20, 2013 www.linear.com 1 2 1 SHEET 1 OF 1 IC NO. REV. 2 MODIFY DATE: TECHNOLOGY TITLE: SCHEMATIC SIZE PRODUCTION EDWIN LI 2 REVISION HISTORY APPROVED DESCRIPTION APPROVALS 2 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 * ECO REV 3 4 A B C D DEMO MANUAL DC1948A Schematic Diagram dc1948af 5 DEMO MANUAL DC1948A 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 dc1948af 6 Linear Technology Corporation LT 0913 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013