DEMO MANUAL DC2243A LT3668 40V Step-Down Regulator with Dual Tracking LDOs Description Demonstration circuit 2243A is a triple power supply that includes one 400mA step-down regulator and two 200mA low dropout (LDO) linear tracking regulators featuring the LT®3668. The demo circuit is designed for one 6V and dual 5V outputs from a 7V to 40V input. Two LDO outputs are configured as post-regulators of the switching regulator output. The total current capability of three output channels is up to 400mA, while the two LDO regulators are capable of 200mA each. The switching frequency of the step-down regulator can be programmed via an oscillator resistor (R8) over a 250kHz to 2.2 MHz range. The default setting is 600kHz. The LT3668 internal boost diode and loop compensation reduce the components count and solution size. The current mode control scheme creates fast transient response and good loop stability. The switching regulator has cycleby-cycle current limit and diode current sense, providing protection against shorted outputs. JP1 can be used to set the whole LT3668 in shutdown mode. JP3 and JP4 enable and disable the outputs of the dual 5V tracking LDOs respectively. The LT3668 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this quick start guide for demo circuit 2243A. Proper board layout is essential for both proper operation and maximum thermal performance. See the data sheet section “PCB Layout”. Design files for this circuit board are available at http://www.linear.com/demo/DC2243A 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 Specifications are at TA = 25°C SYMBOL PARAMETER CONDITIONS VIN1 Input Supply Range of VIN1 fSW Switching Frequency VOUT1 MIN TYP MAX UNITS 7 40 V VIN1 = 12V, VOUT1 = 6V/IOUT1 = 400mA VOUT2 = 5V/IOUT2 = 0 VOUT3 = 5V/IOUT3 = 0 510 690 kHz Output Voltage 1 VIN1 = 12V, VOUT1 = 6V/IOUT1 = 0 ~ 400mA VOUT2 = 5V/IOUT2 = 0 VOUT3 = 5V/IOUT3 = 0 5.88 6.12 V VOUT2 Output Voltage 2 VIN1 = 12V, VOUT1 = 6V/IOUT1 = 0 VOUT2 = 5V/IOUT2 = 0 ~ 190mA VOUT3 = 5V/IOUT3 = 0 4.9 5.1 V VOUT3 Output Voltage 3 VIN1 = 12V, VOUT1 = 6V/IOUT1 = 0 VOUT2 = 5V/IOUT2 = 0 VOUT3 = 5V/IOUT3 = 0 ~ 190mA 4.9 5.1 V IOUT1 + IOUT2 + IOUT3 Maximum Total Output Current 400 IOUT2, IOUT3 Maximum LDO Output Current 190 mA 200 mA dc2243af 1 DEMO MANUAL DC2243A description 100 90 EFFICIENCY (%) 80 70 60 50 40 VOUT1 = 6V fSW = 600kHz IOUT2 = 0A IOUT3 = 0A 30 20 10 0 VIN1 = 12V VIN1 = 24V 0.1 0.2 0.3 VOUT1 LOAD CURRENT (A) 0.4 DC2234 F01 Figure 1. VOUT1 Typical Efficiency vs. Load Current Quick Start Procedure Demonstration circuit 2243A is easy to set up to evaluate the performance of the LT3668. Refer to Figure 2 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 VIN or VOUT and GND terminals. See Figure 3 for the proper scope technique. 1.Place JP1, JP3 and JP4 on the EN position. 2.With power off, connect the input power supply to VIN1 and GND. 4.Turn on the power at the input. NOTE: Make sure that the input voltage does not exceed 40V. 5.Check for the proper output voltages: VOUT1 = 6V, VOUT2 = 5V, VOUT3 = 5V NOTE: If there is no output, temporarily disconnect the load to make sure that the loads are not set too high or are shorted. 6.Once the proper output voltages are established, adjust the loads within the operating ranges and observe the output voltage regulation, ripple voltage, efficiency and other parameters. 3.With power off, connect loads from VOUT1 to GND, from VOUT2 to GND, and from VOUT3 to GND. 2 dc2243af DEMO MANUAL DC2243A Quick Start Procedure – VIN1 + + – VOUT1 – + – LOAD – VOUT3 + – LOAD VOUT2 + + + – – – + – – + + – + LOAD + Figure 2. Proper Measurement Equipment Setup VOUT GND Figure 3. Measuring Input or Output Ripple dc2243af 3 DEMO MANUAL DC2243A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 C2 CAP., X7R 2.2µF 100V 10% 1206 AVX, 12061C225KAT2A 2 1 C3 CAP., X7R 0.22µF 25V 10% 0603 AVX, 06033C224KAT2A 3 1 C4 CAP., NPO 22pF 25V 5% 0603 AVX, 06033A220JAT2A 4 1 C5 CAP., X5R 22µF 25V 20% 1210 MURATA, GRM32ER61E226ME15L 5 2 C7, C11 CAP., X5R 10µF 10V 10% 1206 AVX, 1206ZD106KAT2A 6 2 C9, C10 CAP., X5R 1µF 25V 20% 0603 AVX, 06033D105MAT2A 7 1 D1 DIODE, SCHOTTKY 60V 1A POWERDI123 DIODES INC., DFLS160-7 8 1 L1 INDUCTOR, 27µH SUMIDA, CDRH5D28RHPNP-270MC 9 1 R1 RES., CHIP 243k 0.10W 1% 0603 VISHAY, CRCW0603243KFKEA 10 1 R5 RES., CHIP 150k 0.10W 5% 0603 VISHAY, CRCW0603150KJNEA 11 1 R7 RES., CHIP 931k 0.10W 1% 0603 VISHAY, CRCW0603931KFKEA 12 1 R8 RES., CHIP 174k 0.10W 1% 0603 VISHAY, CRCW0603174KFKEA 13 1 R9 RES., CHIP 294k 0.10W 1% 0603 VISHAY, CRCW0603294KFKEA 14 1 U1 I.C., VOLTAGE REG. MSOP(16)-MSE16 LINEAR TECH., LT3668EMSE#PBF Additional Demo Board Circuit Components 1 1 C1 CAP., Alum 10µF 63V 20% OSCON-CE-6.3 SUN ELECTRONIC INDUSTRIES, 63CE10GA 2 1 C6 CAP., X7R 0.1µF 25V 10% 0603 MURATA, GRM188R71E104KA01D 3 0 C8, C12, C17, C18 (Opt) CAP., 0603 4 2 C13, C14 CAP., X7R 0.047µF 25V 20% 0603 5 0 C15, C16 (OPT) CAP., OSCON-CE-6.3 AVX, 06033C473MAT2A 6 0 C19, C20 (OPT) CAP., 1206 7 0 FB1 (OPT) FERRITE BEAD, 600Ω/500mA 0603 8 0 L2 (OPT) INDUCTOR, 4.7µH SUMIDA, CDRH2D18/LDNP-4R7NC 9 4 R6, R13, R17, R18 RES/JUMPER, CHIP 0Ω 0.25W 5A 0603 VISHAY, CRCW06030000Z0EA 10 2 R10, R12 RES., CHIP 1.50k 0.10W 1% 0603 VISHAY, CRCW06031K50FKEA 11 2 R19, R20 RES., CHIP 200k 0.10W 5% 0603 VISHAY, CRCW0603200KJNEA TDK, MMZ1608S601AT Hardware: For Demo Board Only 1 18 E1–E18 TURRET, TESTPOINT MILL-MAX, 2501-2-00-80-00-00-07-0 2 3 JP1, JP3, JP4 HEADERS, 3 PINS 2mm CTRS. SULLINS, NRPN031PAEN-RC 3 3 XJP1, XJP3, XJP4 SHUNT, 2mm CTRS. SAMTEC, 2SN-BK-G 4 4 MH1–MH4 STANDOFF, NYLON 0.25'' KEYSTONE, 8831(SNAP ON) 4 dc2243af 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 EN DIS EN DIS DIS EN 3 2 1 3 2 1 3 2 1 R10 PG C19 1206 (OPT) E18 47nF C14 1.50k 1% R12 47nF C13 1.50k 1% VIN1 FB1 200k 200k VOUT1 E12 EN3 / ILIM3 E9 EN2 / ILIM2 VIN1 4.7uH C20 CDRH2D18/LDNP‐4R7NC Sumida 1206 (OPT) (OPT) L2 EMI Filter R20 R5 150k VOUT1 C1 10uF 63V R19 E7 + VIN1 MMZ1608S601AT 0603 (OPT) E5 EN E8 E3 E1 4 5 1. ALL RESISTORS ARE 0603 ALL CAPACITORS ARE 0603 4 3 13 12 4 14 C2 2.2µF 100V 1206 VOUT1_5V fs=600KHz 174k 1% R8 NOTE: UNLESS OTHERWISE SPECIFIED VIN1_EMI JP4 EN3 JP3 EN2 JP1 ENABLE GND GND VIN1 7V TO 40V TRANSIENT TO 60V 5 IN1 E2 ADJ3 7 C18 (Opt) 0603 ADJ3 3 6 C11 10µF 10V 1206 OUT3 U1 LT3668EMSE C10 1µF IN2 FB1 DA SW 5 IN3/BD ADJ2 0 Ohm R18 9 10 11 8 16 1 0.22µF OUT2 BOOST 2 C3 C9 1µF C17 (Opt) 0603 E17 ADJ2 R9 294k 1% 0 Ohm R13 D1 DFLS160‐7 VOUT3 0 Ohm R6 931k 1% R7 C4 22pF L1 27µH CDRH5D28RHPNP‐270M Figure 4. DC2243A Demo Circuit Schematic 0 Ohm R17 17 GND EN3/ILIM3 EN2/ILIM2 RT PG EN 15 3 2 2 C7 10µF 10V 1206 R1 243k 1% VOUT1_5V C5 22µF 25V 1210 VOUT3 VOUT2 VOUT1 C12 OPT (Opt) + C16 C8 OPT (Opt) + C15 C6 0.1uF 1 1 E14 E13 E15 E11 E10 E16 E6 E4 GND VOUT3 5V / 200mA IN3/BD GND VOUT2 5V / 200mA IN2 GND * VOUT1 6V / * SEE DEMO MANUAL FOR CURRENT CAPABILITY A B C D DEMO MANUAL DC2243A Schematic Diagram dc2243af 5 DEMO MANUAL DC2243A 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 6 dc2243af Linear Technology Corporation LT 0315 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2015