DEMO MANUAL DC1643A LT3575 Isolated Monolithic Flyback Converter Description Demonstration circuit 1643A is an isolated flyback converter featuring LT®3575, a monolithic switching regulator specifically designed for the isolated flyback converter with an integrated 2.5A, 60V NPN transistor. The DC1643A is designed for 5V output from a 10V to 28V DC input. The output current capability depends on the input voltage, proper cooling, and the switch voltage stress. The output current is up to 1.4A when the input is higher than 10V, and 2A when the input is higher than 20V but less than 28V. The output current should not be higher than 2.4A for safe operation. The IC requires minimum load to maintain good output voltage regulation. A Zener diode D4 across the output clamps the voltage to ~5.4V. The light load regulation can be improved if a preload resistor (R4, optional) is installed. Depending on input voltage and output regulation, a 40mA minimum load is usually sufficient. The DC1643A can be easily modified to generate different output voltages. Some pre-designed transformers from vendors such as Würth Electronics, Sumida, Pulse Engineering and Coilcraft, can be used for various applications. The LT3575 operates with input supply voltages from 3V to 40V. The part senses the isolated output voltage directly from the primary side flyback waveform. No third winding or opto-coupler is required for regulation. The LT3575 utilizes boundary mode operation to provide a high efficiency, small size solution with improved load regulation. It can be used in industrial, automotive and medical applications where an isolated output is required. The LT3575 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 DC1643A. 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. Performance Summary PARAMETER (TA = 25°C) CONDITION Input Voltage MIN TYP 10 4.75 MAX 28 5 5.25 UNITS V Output Voltage, VOUT VIN = 10V to 28V, IOUT = 1.4A Minimum Output Current VIN = 20V Maximum Output Current VIN = 10V to 20V VIN = 21V to 28V Switching Frequency VIN = 10V, IOUT = 1.4A 90 kHz Efficiency VIN = 28V, IOUT = 2A 86 % 40 V mA 1.4 2 A A dc1643af 1 DEMO MANUAL DC1643A Quick Start Procedure DC1643A is easy to set up to evaluate the performance of the LT3575. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: ing frequency ripple can be reduced by increasing the output capacitor C4, or adding a second stage LC filter. Please contact factory for more information. 1.With power off, connect the input power supply to VIN (E1) and GND (E2). Note: The input EMI filter circuit (L1, FB1, C5, C19, and C20) can be added by cutting the copper plane along the notch next to C2 and C8 on the top layer of the demo circuit. 2.Connect the load to the terminals VOUT+ (E5) and VOUT – (E6) on the board. Apply 100mA load to VOUT+ and VOUT –. 3.Turn on the power at the input. Increase VIN to 10V slowly. Note: Make sure that the input voltage does not exceed 28V. 4. Check for the proper output voltages. The output should be regulated at 5V (±5%). Note: If there is no output, temporarily disconnect the power supply. Make sure that the load is connected with correct polarity. If the output voltage is out of spec, make sure minimum load current is applied to the output, the load is not set too high, and the input current does not hit the power supply current limit. Note: The compensation loop is designed with tradeoff between transient response and output ripple. To reduce the low frequency output ripple, slow down the loop by reducing R15 and increasing C11 (for instance, change R15 to 6.4kΩ, and C11 to 22nF). The switch- Note: For overload conditions, it is recommended to operate the board at a reduced input voltage range and/or reduce R8 of the RCD snubber. Please contact the factory for more information. 5. Once the proper output voltage is established, adjust the input and load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Note: When measuring the input or output voltage ripples, 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 and GND, or VOUT+ and VOUT – terminals. See Figure 2 for proper scope probe technique. Typical efficiency and regulation curves are plotted in Figures 3 and 4, respectively. 6.Turn off the power supply. Disconnect the load from the demo circuit. dc1643af 2 DEMO MANUAL DC1643A quick start procedure Figure 1. Proper Measurement Equipment Setup INPUT OR OUTPUT CAPACITOR 100 5.8 90 5.6 80 5.4 70 OUTPUT VOLTAGE (V) EFFICIENCY (%) Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple 60 50 40 30 5.2 5.0 4.8 4.6 4.4 20 10 0 0.1 VIN = 10V VIN = 28V 0.6 1.6 1.1 LOAD CURRENT (A) 4.2 2 DC1643A F03 Figure 3. Typical Efficiency Curves VIN = 10V VIN = 28V 4.0 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 LOAD CURRENT (A) DC1643A F04 Figure 4. Typical Regulation Curves dc1643af 3 DEMO MANUAL DC1643A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER 1 1 C1 Capacitor, 22µF 20% 50V Electrolytic Sun Electronics 50CE22BS 2 1 C2 Capacitor, 1210 4.7µF 10% 50V X7R Murata GRM32ER71H475KA88L 3 1 C4 Capacitor, 1210 47µF 10% 10V X7R Murata GRM32ER71A476K 4 1 C7 Capacitor, 0603 0.1µF 10% 25V X5R TDK C1608X5R1E104K 5 1 C8 Capacitor, 0603 100pF 5% 50V NPO AVX 06035A101JAT2A 6 2 C9, C12 Capacitor, 0805 1µF 10% 50V X7R Murata GRM21BR71H105KA12L 7 1 C10 Capacitor, 0805 0.22µF 10% 50V X7R Taiyo Yuden UMK212B7224KG-T 8 1 C11 Capacitor, 0603 2200pF 10% 50V X7R AVX 06035C222KAT2A 9 1 C13 Capacitor, 0603 10pF 5% 50V NPO AVX 06035A100JAT2A 10 1 D1 Diode, Schottky, Barrier Rectifier 8A Micro Semiconductor UPS840 11 1 D2 Diode, Schottky Diode Inc. DFLS1100-7 12 1 D3 Diode, Schottky SOD323 Central Semiconductor CMDSH-3 13 1 D4 Diode, Power Zener 1.0W Diodes/Zetex DFLZ5V6-7 14 1 R3 Resistor, 0603 357kΩ 1% 1/10W NIC NRC06F3573TRF 15 1 R6 Resistor, 0603 93.1kΩ 1% 1/10W Vishay CRCW060393K1FKED 16 1 R7 Resistor, 0603 80.6kΩ 1% 1/10W Vishay, CRCW060380K6FKEA 17 1 R8 Resistor, 0805 2kΩ 1% 1/8W Vishay CRCW08052K00FKEA 18 1 R9 Resistor, 0603 28.7kΩ 1% 1/10W NIC NRC06F2872TRF 19 1 R10 Resistor, 0603 10kΩ 1% 1/10W Vishay CRCW060310K0FKED 20 1 R11 Resistor, 0603 6.04kΩ 1% 1/10W NIC NRC06F6041TRF 21 1 R15 Resistor, 0603 24.9kΩ 1% 1/10W NIC NRC06F2492TRF 22 1 T1 Transformer Würth 750311675 23 1 U1 IC, Monolithic Flyback Converter Linear Technology LT3575EFE Hardware – For Demo Board Only 1 5 Turret Mill-Max 2501-2-00-80-00-00-07-0 2 1 E1, E2, E3, E5, E6 Fab, Printed Circuit Board DC1643A 3 1 Stencil Stencil Capacitor, 22µF 20% 50V Electrolytic Optional Sun Electronics 50CE22BS Optional Additional Demo Board Circuit Components 1 0 C5 2 0 C14 Capacitor, 1206 0.033µF Optional Optional 3 0 C19 Capacitor, 1210 4.7µF 10% 50V X7R Optional Murata GRM32ER71H475K Option 4 0 C20 Capacitor, 0603 0.01µF 10% 50V X7R Optional NIC NMC0603X7R104K50TRPF Optional 5 0 FB1 Ferrite Bead Optional Taiyo Yuden FB MJ3216HS800 Optional 6 0 L1 Inductor, 10µH Optional Sumida CDRH4D22/HP Optional 7 0 Q1 XSTR, MOSFET, N-Channel 30V Optional Vishay Si3456DDV Optional 8 0 R4 Resistor, 0805 440Ω 1% 1/8W Optional NIC NRC10F4400TRF dc1643af 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 E3 22uF 50V + C1 R10 10k 1% C7 0.1uF SUN ELECT. 50CE22BS VIN C8 100pF C2 4.7uF 50V 1210 5 U1 LT3575EFE VC SS RILIM TC SHDN/UVLO 1. ALL CAPACITOR AND RESISTOR CASE SIZES ARE 0603. C11 2200pF 9 7 8 12 6 C12 1uF 50V 0805 R15 24.9k 1% R3 357K 1% R6 93.1k 1% NOTES: UNLESS OTHERWISE SPECIFIED, R9 28.7k 1% SHDN GND E2 10V - 28V VIN E1 4 5 RREF RFB SW SW R11 6.04k 1% R7 80.6k 1% C13 10pF D2 DFLS1100 C10 0.22uF 50V 0805 2 R8 2k 1% 0805 4 3 C20 0.01uF 50V 1 2 D1 VIN N/A DFLZ5V6 5.6V D4 C4 47uF 1210 10V BEAD C19 4.7uF 50V 1210 OPT TECHNOLOGY 1206 C14 10uH E6 22uF 50V SUN ELECT. 50CE22BS VOUT- + C5 VIN R4 OPT 0805 E5 VOUT+ VOUT- +5V @1.4A, VIN > 10V +5V @2.0A, VIN > 20V VOUT+ APPROVED Zhongming Y. 2 1 DEMO CIRCUIT 1643A LT3575EFE ISOLATED MONOLITHIC FLYBACK CONVERTER 2 SUMIDA CDRH4D22/HP L1 OPTIONAL CIRCUIT TAIYO YUDEN FB MJ3216HS800 FB1 UPS840 3 DATE 07/02/10 DESCRIPTION PRODUCTION 1 2 REVISION HISTORY REV 2 8 3 750311675 7 4 6 5 T1 ECO 2 1 11 10 4 3 C9 1uF 50V 0805 1 D3 CMDSH-3 3 1 2 D 1 NC 2 VIN TEST 13 GND 14 NC NC 15 16 BIAS GND 17 1 2 5 A B C D DEMO MANUAL DC1643A Schematic Diagram dc1643af 5 DEMO MANUAL DC1643A 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 dc1643af 6 Linear Technology Corporation LT 1111 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2011