DEMO MANUAL DC7A Description Demonstration circuit 7A is a high input voltage, 4mA step-down regulator featuring the LTC78. The output of the regulator can be programmed for either 5V,.V or.8v with on-board jumpers or is adjustable from 8mV to V IN using an optional feedback divider. The input voltage range is from 4V to 4V. The LTC78 s Burst Mode operation, low quiescent current and internal top FET switch provide high efficiency over a wide range of loads. Other features include: Optional components to adjust the current limit, make it proportional to V IN or improve the efficiency and reduce the output voltage ripple. LTC78 High Efficiency, High V IN, Step-Down Regulator FBO turret to tie two or more LTC78 regulators together if the application requires more load current. Optional UVLO and OVLO divider. External/internal soft-start. For more details, refer to the LTC78 data sheet. The LTC78 data sheet gives a complete description of the IC operation and application information. The data sheet must be read in conjunction with this quick start guide. Design files for this circuit board are available at http://www.linear.com/demo/dc7a 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. Performance Summary Specifications are at T A = 5 C PARAMETER CONDITIONS VALUE Input Voltage Range 4V to 4V 5.V Output Voltage V IN = V, I OUT = ma to 4mA 5.V ±%.V Output Voltage V IN = V, I OUT = ma to 4mA.V ±%.8V Output Voltage V IN = V, I OUT = ma to 4mA.8V ±% Maximum Output Current, I OUT V IN = 4V to 4V, V OUT = 5.,.V,.8V or ADJ (V OUT V IN ) 4mA Typical Efficiency V IN = V, V OUT = 5V, I OUT = 4mA 8.% Typical Output Ripple V IN = V, V OUT = 5V, I OUT = 4mA 87mV P-P dc7af
DEMO MANUAL DC7A Quick Start Procedure Demonstration circuit 7A is easy to set up to evaluate the performance of the LTC78. Please refer to Figure for proper measurement equipment setup and follow the procedure below. ) With power off, connect the input supply, load and meters as shown in Figure. Preset the load to A and V IN supply to V. ) Place the RUN pin jumper (JP) in the ON position. ) Set the output to 5V by placing the JP jumper in the B position and the JP jumper in the A position. 4) Turn-on the V IN supply and increase to V. The 5V output should be 5V ±% per the Performance Summary table. 5) Next, apply 4mA load to the output and re-measure V OUT. 6) Once the DC regulation is confirmed, observe the output voltage ripple, load step response, efficiency and other parameters for the 5V,.V and.8v output settings. Note. CAUTION: The maximum input voltage of the DC7A is 4V. Voltages of 4V or lower are high enough to cause electric shock. Use great care when testing this demo board. Note. For a 5V output, the input voltage should be 6V or more. Note. When measuring the output or input voltage ripple, do not use the long ground lead on the oscilloscope probe. See Figure for the proper scope probe technique. Short, stiff leads need to be soldered to the (+) and ( ) terminals of an output capacitor. The probe s ground ring needs to touch the ( ) lead and the probe tip needs to touch the (+) lead. dc7af
DEMO MANUAL DC7A Quick Start Procedure I IN I OUT + V IN SUPPLY V OUT LOAD + Figure. Proper Measurement Equipment Setup + C OUT V OUT Figure. Measuring Output Voltage Ripple dc7af
DEMO MANUAL DC7A Quick Start Procedure 9 8 7 6 L = Sumida CDRH5RNP-5NC (5µH, DCR = 85mΩ typ) V OUT = 5V Efficiency (%) 5 4 V IN 48V IN V IN 4V IN.., Load Current (ma) Figure. Efficiency at 5V OUT dc7a F 8 7 6 L = Sumida CDRH5RNP-5NC (5µH, DCR = 85mΩ typ) V OUT =.V Efficiency (%) 5 4 V IN 48V IN V IN 4V IN.., Load Current (ma) Figure 4. Efficiency at.v OUT dc7a F4 4 dc7af
DEMO MANUAL DC7A Quick Start Procedure 7 6 L = Sumida CDRH5RNP-5NC (5µH, DCR = 85mΩ typ) V OUT =.8V 5 Efficiency (%) 4 V IN 48V IN V IN 4V IN.., Load Current (ma) Figure 5. Efficiency at.8v OUT dc7a F5 dc7af 5
DEMO MANUAL DC7A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components C CAP µf, V, ELEC NIPPON CHEMI-CON, EMVEARAMKG5S C CAP µf,, %, V, X7R KEMET CX5KRACTU C4 CAP 47nF, 6, %, 5V, X7R AVX 6C47KATA 4 C6, C7 CAP µf,, %, V, X7R TAIYO YUDEN LMK5ABJ7MMH-T 5 C9 CAP.µF, 6, %, 5V, X7R AVX 6C4KATA 6 D DIODE SBRUP DIODES, SBRUP-7 7 L INDUCTOR 5µH SUMIDA CDRH5RNP-5NC 8 R RES M, 6Ω, 5%, /W VISHAY CRCW6MJNEA 9 U IC LTC78EMSE LINEAR TECH LTC78EMSE#PBF Additional Demo Board Circuit Components C CAP 6 OPTION OPTION C8, C CAP OPTION OPTION R, R4, R7, R8 RES 6 OPTION OPTION 4 R, R6 RES Ω 6 JUMPER VISHAY CRCW6ZED Hardware 5 E, E, E, E4, E5 TURRET MILL-MAX 5---8---7- JP, JP, JP HEADER mm PIN SULLINS, NRPNPAEN-RC 4 MH, MH, MH, MH4 STANDOFF SNAP ON KEYSTONE_88 4 JP, JP, JP SHUNT mm SAMTEC SN-BK-G 6 dc7af
DEMO MANUAL DC7A Schematic Diagram 5 4 D D VIN U LTC78EMSE L 5uH E C VOUT R uf VIN SW VOUT CDRH5R C6 C8 C M C7 C + V C9 uf.8v /.V / 5V D R6 V uf OPT.uF 4mA 4 SBRUP V RUN ANODE 6 R VFB 9 E OPT RUN JP SS R7 ON OFF OPT OVLO C4 47nF [] 4. SMALLER AMOUNT OF COUT CAN BE USED R FOR APPLICATIONS THAT CAN TOLERATE 5 B FBO HIGHER OUPUT RIPPLE. VPRG 7 REFER TO THE DATA SHEET FOR R8 A APPLICATIONS INFORMATION. VIN JP ISET VPRG 6 OPT [] E VIN 4V - 4V E4 C C E5 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. FB NC NC NC NC B 7 8 4 5 C OPT R4 OPT A B B JP NOTE: UNLESS OTHERWISE SPECIFIED. ALL RESISTORS ARE 6. ALL CAPACITORS ARE 6.. FOR 5V OUTPUT, VIN RANGE IS 6V-4V. 6 McCarthy Blvd. Milpitas, CA 955 Phone: (48)4-9 JP JP [] APPROVALS CUSTOMER NOTICE LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;.V A B TECHNOLOGY Fax: (48)44-57 HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL LTC Confidential-For Customer Use Only 5.V B A APPLICATION. COMPONENT SUBSTITUTION AND PRINTED A APP ENG. TITLE: SCHEMATIC A CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT EXT. R A A PERFORMANCE OR RELIABILITY. CONTACT LINEAR HIGH EFFICIENCY, HIGH VIN, 4mA TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. www.linear.com B B VOUT.8V STEP-DOWN REGULATOR REV. IC NO. SIZE LTC78EMSE DEMO CIRCUIT 7A N/A Tuesday, January 6, 5 SHEET OF DATE: THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. SCALE = NONE 4 5 dc7af 7
DEMO MANUAL DC7A 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 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 6 McCarthy Blvd. Milpitas, CA 955 Copyright 4, Linear Technology Corporation 8 LT 5 PRINTED IN USA Linear Technology Corporation 6 McCarthy Blvd., Milpitas, CA 955-747 (48) 4-9 FAX: (48) 44-57 www.linear.com LINEAR TECHNOLOGY CORPORATION 5 dc7af