LT3905

LT3905 LINER

Document overview

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Technical content

Description

Boost DC/DC Converter with APD Current Monitor Demonstration circuit 1956A features the LT®3905, a boost DC/DC Converter with APD current monitor that comes in a 3mm × 3mm QFN package. This demo board is designed to convert a 2.7V to 12V input to a 50V output at 2mA. The LT3905 is equipped with indicators for monitoring APD current, overload, and loss-of-signal (LOS) conditions, which can easily be changed with their respective resis - tors. In addition, the output voltage can be adjusted via the CTRL pin. DC1956A is designed for 1MHz operation but can also be programmed for 2MHz by moving jumper JP2. For measuring fast transient response, use the installed Fast Monitor Response Circuit on the bottom of the demo board and install 0Ω resistors at R14 and R20. Also, remove R11 and any other capacitances or probes across the APD node. The transient response should be measured at the TIA turret. For further information, read the APD Current Monitor T ransient Response section in the data sheet. The internal LOS_MON comparator hysteresis is 20mV on the rising edge of the LOS_MON voltage. For additional hysteresis, use R6, R7, R15, and R21 as stated in the Loss of Signal Hysteresis section in the data sheet. L, L T , L TC, L TM, 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 The LT3905 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 the DC1956A. Design files for this circuit board are available at http://www.linear.com/demo/DC1956A Specifications are at TA = 25°C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Input Supply Range 2.7 12 V VOUT Output Voltage Range VIN = 3.3V, IAPD = 1mA 48 50 52 V fSW Switching Frequency JP2: 1MHz 0.9 1 1.1 MHz ILOS Loss-of-Signal APD Current R10 = 1MΩ 12.5 µA ILIM APD Current Limit R8 = 12.4kΩ 2 mA VMON/IAPD MON Voltage to APD Current Ratio R11 = 4.99kΩ 1 mV/µA IAPD (mA) INPUT CURRENT (mA) 100 DC1956A F01 20 0.5 1.5 VAPD = 50V VIN = 3.3V VIN = 5V Figure 1. DC1956A Input Current vs APD Current

Demonstration circuit 1956 is easy to set up to evaluate the performance of the LT3905. Refer to Figure 2 for proper measurement equipment setup and follow the procedure below: NOTE. When measuring the output voltage ripple, connect a BNC cable from the oscilloscope to J1. Make sure there are no other cables connected to the APD node. Place jumpers in the following positions: JP1: Run JP2: 1 MHz 2. With power off, connect the input power supply to VIN and GND. 3. Turn on the power at the input. NOTE: Make sure that the input voltage does not exceed 16V. 4. Connect a 50K resistor from APD to GND and check for the proper output voltage. VOUT = APD = 48V to 52V. NOTE: If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 5. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters.

Figure 2. Proper Measurement Equipment Setup

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 C1 CAP., X7R, 1µF, 25V, 10% 0805 AVX, 0805YC105KAT2A 2 1 C5 CAP., X7R, 0.22µF, 100V, 10% 1206 AVX, 12061C224KAT2A 3 1 L1 INDUCTOR, 10µH COOPER Bussmann, SD3110-100-R 4 3 R1, R4, R5 RES., CHIP, 100k, 1/10W, 1% 0603 VISHAY, CRCW0603100KFKEA 5 3 R3, R7, R10 RES., CHIP, 1M, 1/10W, 1% 0603 VISHAY, CRCW06031M00FKEA 6 1 R8 RES., CHIP, 12.4k, 1/10W, 1% 0603 VISHAY, CRCW060312K4FKEA 7 1 R11 RES., CHIP, 4.99k, 1/10W, 1% 0603 VISHAY, CRCW0603604KFKEA 8 1 R12 RES., CHIP, 634k, 1/10W, 1% 0603 VISHAY, CRCW0603634KFKEA 9 1 R13 RES., CHIP, 15.0k, 1/10W, 1% 0603 VISHAY, CRCW060315K0FKEA 10 2 R15, R16 RES., CHIP, 0, 1/10W, 1% 0603 VISHAY, CRCW0603000Z0EA 11 1 U1 I.C. LT3905EUD, 16 PIN, 3×3mm LINEAR TECH, LT3905EUD#PBF Additional Demo Board Circuit Components 1 0 C2, C3, C4, C6 (OPT ) CAP., 0603 2 0 C8 (OPT ) CAP., 0805 3 1 C9 CAP., C0G, 0.5pF, 50V, 5% 0603 AVX, 06035A0R5KJAT2A 4 1 C10 CAP., X7R, 0.1µF, 16V, 10% 0603 AVX, 0603YC104KAT2A 5 2 C11, C12 CAP., X7R, 1µF, 16V, 10% 0603 AVX, 0603YC105KAT2A 6 1 Q1 TRANS., NPN 100V 2.5A MED SOT23-3 DIODES / ZETEX, ZXTN25100DFHTA 7 0 R2, R6, R9, R14, R20, R21 RES., 0603 8 2 R18, R19 RES., CHIP, 4.99k, 1/10W, 1% 0603 VISHAY, CRCW0603604KFKEA 9 1 R17 RES., CHIP, 1k, 1/10W, 1% 0603 VISHAY, CRCW06031K00FKEA 1 U2 I.C., LT6210CS6, TSOT23-6 LINEAR TECH, LT6210CS6#PBF 11 1 U3 I.C., LT1790BIS6-2.048, TSOT23 LINEAR TECH, LT1790BIS6-2.048 Hardware: For Demo Board Only 1 14 E1-E14 TESTPOINT, TURRET, .094" pbf MILL-MAX, 2501-2-00-80-00-00-07-0 2 2 JP1, JP2 3 PIN 0.079 SINGLE ROW HEADER SULLINS, NRPN031PAEN-RC 3 2 XJP1, XJP2 SHUNT, .079" CENTER SAMTEC, 2SN-BK-G 4 1 J1 CONN, BNC, 5 PINS CONNEX 112404 5 4 Stand-Off STAND-OFF, NYLON 0.25" KEYSTONE, 8831(SNAP ON)

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 representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. schematic Diagram D D C C B B A A 1. ALL RESISTORS ARE 0603. ALL CAPACITORS ARE 0603. NOTE: UNLESS OTHERWISE SPECIFIED VIN 2.7V - 12V EN 1MHz 2MHz CTRL GND GND ILIM LOS ILIM_MON LOS_MON MON APD 50V / 2mA LOAD STEP CIRCUIT PWM TIA FAST MONITOR RESPONSE CIRCUIT RUN SHDN COPPER BUSSMANN SD3110-100-R LOS ADJ (12.5uA LOS) (2mA Limit) (1mV/uA) VIN VIN VIN VIN VIN VIN VIN MON MON E5E5 E12E12 E10E10 100K 100K R18 4.99KR18 4.99K R20 OPT R20 OPT E9E9 OPT OPT 10uH 10uH ZXTN25100DFH ZXTN25100DFH 1uF 25V 0805 1uF 25V 0805 R17 1KR17 1K R12 634K R12 634K E11E11 R13 15.0K R13 15.0K R11 4.99K R11 4.99K C9 0.5pFC9 0.5pF E4E4 Iset U2 LT6210CS6 Iset U2 LT6210CS6 R16 R16 E13E13 R21 OPT R21 OPT C10 0.1uF C10 0.1uF LT3905EUD LT3905EUD ILIM1 LOS_MON ILIM_MON MON APD 5 MONIN SW VOUT GND 9 VIN EN/UVLO11 CTRL12 LOS13 LOS_ADJ14 FB 15FSEL16 GND 17 C11 1uF C11 1uF OPT OPT E3E3 OPT OPT R14 OPT R14 OPT OPT OPT 100K 100K LT1790BIS6-2.048 LT1790BIS6-2.048 VIN4 GND2 OUT 6 GND1 NC3 NC5 OPT OPT E1E1 C12 1uF C12 1uF JP2JP2 R19 4.99K R19 4.99K OPT OPT 12.4K 12.4K E6E6 R15 R15 0.22uF 100V 1206 0.22uF 100V 1206 E14E14 100K 100K OPT OPT BNC BNC JP1JP1 E7E7 E2E2 R10 R10 E8E8 OPT 0805 100V OPT 0805 100V

DEMO MANUAL DC1956A Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear .com  LINEAR TECHNOLOGY CORPORATION 2013 LT 0114 REV A • PRINTED IN USA DEMONSTRATION BOARD IMPORTANT NOTICE Linear Technology Corporation (LT C) 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 ONL Y and is not provided by LT C 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 P ARTY 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 LT C 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. LT C assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. LT C 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 LT C applica- tion engineer . Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation