DEMO MANUAL DC1754A Description LTC3104EDHD 2.8µA Quiescent Current, 15V, 300mA Synchronous Step-Down DC/DC Converter and 10mA Quiescent Demonstration Circuit 1754A features the LTC®3104, a high efficiency, monolithic synchronous step-down converter using a current mode architecture capable of supplying 300mA of output current. The IC operates with a fixed frequency oscillator at 1.2MHz. The LTC3104 has two user selectable (JP3) operating modes: Burst Mode® operation and forced continuous operation (fixed frequency PWM). The IC has internal compensation and an accurate programmable RUN pin. The LTC3104 also incorporates a programmable LDO which can be operated from VIN , VOUT or an independent supply. Jumper JP4 provides a convenient way to change the input supply to the LDO. The LDO can also be independently turned off or on through JP2. The LTC3104 operates with a 2.5V to 15V input voltage range. The demo board has been designed with the Performance Summary main output set to 3.3V and the LDO output (VLDO) to 1.8V. Since the LTC3104 is a buck converter, as VIN approaches VOUT, the output will start dropping out of regulation. Consult the data sheet for information on the minimum VIN to VOUT differential for regulation. The regulation range is also a function of the load current. Typical demo board efficiency is shown in Figures 1 and 2. The LTC3104 data sheet has detailed information about the operation, specification and applications of the part. The data sheet should be read in conjunction with this Quick Start Guide. Design files for this circuit board are available. Call the LTC factory. 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. (TA = 25°C) PARAMETER CONDITIONS TYPICAL VALUE Input Voltage Range (See Note 1) 2.5V to 15V VOUT (See Note 1) 3.3V VLDO 1.8V IOUT 300mA IOUT LDO 10mA Note 1. The demo board can operate with VIN less than VOUT, however VOUT will drop out of regulation. The regulation range is a function of IOUT. Please refer to the data sheet for more information. dc1754Af 1 DEMO MANUAL DC1754A Quick Start Procedure Using short twisted-pair leads for any power connections and with all loads and power supplies off, refer to Figure 3 for the proper measurement and equipment setup. The battery/power supply (PS1) should not be connected to the circuit until it is stated in the following procedure. 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 VIN or VOUT and GND terminals (see Figure 4), or by using an oscilloscope probe tip jack. 1. Jumper, PS1 and LOAD settings to start: PS1 = OFF 4. Connect a load to VLDO, as shown in Figure 3. The load can be up to 10mA or 180Ω for VLDO = 1.8V. Again, connect an ammeter if accurate current measurement or monitoring is desired. 5. Turn on PS1 and slowly increase voltage until the voltage at VIN is 5V. Move Jumper JP1 to ON. 6. Verify VOUT is ~3.3V. 7. Move Jumper JP2 to ON. 8. Verify VLDO is ~1.8V 9.VIN can now be varied between 4.1V and 15V. VOUT should remain in regulation. 10.VIN can also be varied down to 2.5V. For VIN ≤ 4.1V, VOUT may drop out of regulation as previously described. VLDO should remain in regulation. JP1 (RUN) = OFF JP2 (RUNLDO) = OFF 11.IOUT can also be varied from 0mA to 300mA. IOUT VLDO may also be varied from 0mA to 10mA. JP3 (MODE) = FIXED FREQUENCY JP4 (VLDO) = VOUT 2. With power off, connect the power supply (PS1) as shown in Figure 3. If accurate current measurements are desired (for efficiency calculation for example), then connect an ammeter in series with the supply as shown. The ammeter is not required, however. 3. Connect a load to VOUT, as shown in Figure 3. The load can be up to 300mA or 11Ω for VOUT = 3.3V. Connect an ammeter if accurate current measurement or monitoring is desired. 12.For Burst Mode operation, move jumper JP2 to BURST. See the data sheet for more information. NOTES: (1) If VOUT drops out of regulation, check to be sure the maximum load has not been exceeded, or that VIN is not below the minimum value for regulation (see the data sheet). (2) To measure no-load input current, remove R4. 100 100 95 95 100mA LOAD 300mA LOAD 85 80 75 70 65 85 70 65 60 55 5 7 11 9 VIN (V) 13 15 dc1754a F01 Figure 1. DC1754A Efficiency in PWM Mode 5mA LOAD 75 55 3 1mA LOAD 80 60 50 10mA LOAD 90 EFFICIENCY (%) EFFICIENCY (%) 90 50 3 5 7 11 9 VIN (V) 13 15 dc1754a F02 Figure 2. DC1754A Efficiency in Burst Mode Operation dc1754Af 2 DEMO MANUAL DC1754A quick start procedure Figure 3. Proper Measurement Equipment Setup GND VIN Figure 4. Measuring Input or Output Ripple dc1754Af 3 DEMO MANUAL DC1754A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 C1 CAP CER, 10µF, 25V, X5R, 1210 TDK, C3225X5R1E106M 2 3 C2, C4, C6 CAP CER, 1µF, 25V, X5R, 0603 TDK, C1608X5R1E105M 3 1 C3 CAP CER, 22µF, 10V, X5R, 20%, 1206 TDK, C3216X5R1A226M 4 1 C5 CAP CER, 4.7µF, 6.3V, X5R, 0603 TDK, C1608X5R0J475K 5 1 C7 CAP CER, 12pF, 50V, C0G 5%, 0603 TDK, C1608C0G1H120J 6 1 C8 CAP CER, 0.1µF, 50V, X7R, 0603 TDK, C1608X7R1H104M 7 1 L1 Inductor, 15µH Coilcraft, LPS4018-153MLB 8 2 R1, R5 RES, 2MΩ, 1/10W, 1%, 0402, SMD Panasonic, ERJ-2GEJ205X 9 1 R2 RES, 2.21kΩ, 1/10W, 1%, 0402, SMD Panasonic, ERJ-2RKF2211X 10 5 R3, R4, R7, R8, R10 RES, 1MΩ, 1/10W, 1%, 0402, SMD Panasonic, ERJ2RKF1004X 11 1 R6 RES, 442kΩ, 1/10W, 1%, 0402, SMD Panasonic, ERJ-2RKF4423X 12 1 U1 LTC3104EDE, DFN14DE Linear Technology Corporation, LTC3104EDHD Additional Demo Board Circuit Components 1 0 C9 (OPT) OPT CAP TANT, 68µF, 20V, 10%, SMD, 7343 OPT 2 1 C10 OPT CAP CER, 1000pF, 50V, X7R, 20%, 0603 OPT 3 0 R9 OPT RES, 1/10W, 1%, 0402, SMD OPT Hardware—for Demo Board Only 1 6 E1, E2, E3, E4, E5, E6 Testpoint, Turret 0.094 " Mill-Max, 2501-2-00-80-00-00-07-0 2 4 JP1, JP2, JP3, JP4 JMP, 0.079 " Single Row Header, 3-Pin Samtec, TMM-103-02-L-S 3 4 XJP1, XJP2, XJP3, XJP4 Shunt, 0.079 " Center Samtec, 2SN-BK-G 4 4 (Stand-Offs) Keystone, 8832 (Snap on) Stand-Off, Nylon, 0.375 " Tall dc1754Af 4 DEMO MANUAL DC1754A R9 DNP C10 DNP Figure 5. Circuit Schematic Schematic Diagram dc1754Af 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. 5 DEMO MANUAL DC1754A 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 dc1754Af 6 Linear Technology Corporation LT 1211 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2011