DEMO MANUAL DC2041A LTC3255EMSE Wide VIN Range Fault Protected 50mA Step-Down Charge Pump Description Demonstration circuit 2041A is a switched-capacitor step-down power supply featuring the LTC(R)3255. The LTC3255 has the ability to step down voltage 2:1 to efficiently regulate output voltages less than half the VIN voltage reducing the input current needed. As VIN reduces below twice VOUT, the LTC3255 will automatically switch to 1:1 mode. The LTC3255 also has an integrated shunt regulator allowing it to provide a regulated output from a 4mA to 20mA current loop. Performance Summary PARAMETER The LTC3255 is a robust device that can survive reversepolarity input supplies with current limit and overtemperature protection. Refer to the LTC3255 data sheet for more details on the electrical and timing specifications. 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. Specifications are at TA = 25C CONDITIONS MIN Input Supply Range VOUT Shunt Jumper = OFF (SHUNT = GND) Shunt Jumper = ON (SHUNT = BIAS) IIN = 4mA IOUT 48 2.4 12.5 50 7.4 EN 4mA TO 20mA INPUT >10V COMPLIANCE 1F - C- 220k LTC3255 PGOOD 2.15M SHUNT 0.1F OUTPUT 3.3V 7.4mA VOUT PGOOD BIAS GND V V mA mA 7.8 40 10F FB 1.21M DC2041A F01 AVAILABLE OUTPUT CURRENT (mA) VIN UNITS Available Output Current vs Input Current 1F + MAX 4 7.4mA DC Supply from 4mA to 20mA Current Loop C+ TYP 37 34 31 28 AVAILABLE IOUT 25 22 INCREASED IOUT CAPABILITY 19 16 13 INPUT CURRENT 10 7 4 4 6 10 12 14 16 8 INPUT CURRENT (mA) 18 20 DC2041A F02 dc2041af 1 DEMO MANUAL DC2041A Quick Start Procedure The DC2041 is easy to set up to evaluate the performance of the LTC3255 with the shunt disabled. Refer to Figure 1 for proper measurement equipment setup with the shunt disabled and follow the evaluation procedure below. To evaluate the LTC3255 with the shunt enabled, go to the SHUNT ENABLED section. 4. With power off, connect a 0V to 48V, 100mA power supply to VIN and GND with a voltmeter as shown in Figure 1. 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 2 for proper scope probe technique. NOTE. Make sure that the input voltages do not exceed 60V. 1. Set the EN jumper, JP1, on the DC2041 board to the ON position. 7. With a 50mA load on VOUT, increase VIN until the current on VIN drops to approximately 1/2 the VOUT current. 2. Set the SHUNT jumper, JP3, to the OFF position. 8. Refer to the LTC3255 data sheet for more details on how the LTC3255 operates. 3. Set the VOUT jumper, JP2, to the desired output voltage. NOTE. Do not set the VOUT jumper to the OPT setting unless the appropriate resistor is installed in R7. The VOUT jumper OPT position is to allow an alternate VOUT setting. This can be accomplished by adding a resistor to R7 to set the output to a desired voltage. Refer to the LTC3255 data sheet to calculate the appropriate value for R7. 2 5. Turn on the VIN input power supply and increase the supply until the VOUT voltage is in regulation and the PGOOD voltage is pulled to VOUT. 6. With VIN at least 1V above VOUT, increase the load on VOUT from 0mA to 50mA and observe the input current. The output ripple may also be observed using an oscilloscope with the probe connected as shown in Figure 2. 9. When done, turn off all loads and power supplies. dc2041af DEMO MANUAL DC2041A Quick Start Procedure - PS1 0V TO 48V 100mA Supply + + - + - + - + - + L1 0mA TO 100mA Load DC2041 F01 - Figure 1. Proper Measurement Equipment Setup with Shunt Disabled GND VIN Figure 2. Measuring Input or Output Ripple dc2041af 3 DEMO MANUAL DC2041A SHUNT ENABLED The DC2041 is easy to set up to evaluate the performance of the LTC3255 with the shunt enabled. Refer to Figure 3 for proper measurement equipment setup of the LTC3255 with the shunt enabled and follow the evaluation procedure. 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 2x for proper scope probe technique. 1. Set the EN jumper, JP1, on the DC2041 board to the ON position. 2. Set the SHUNT jumper, JP3, to the ON position. 3. Set the VOUT jumper, JP2, to the desired output voltage. NOTE. Do not set the VOUT jumper to the OPT setting unless the appropriate resistor is installed in R7. The VOUT jumper OPT position is to allow an alternate VOUT setting. This can be accomplished by adding a resistor to R7 to set the output to a desired voltage. Refer to the LTC3255 data sheet to calculate the appropriate value for R7. 4. With power off, connect a 0V to 48V, 100mA power supply to a controlled current source, a 250 1/4 Watt resistor, VIN and GND with a voltmeter and ammeter as shown in Figure 3. 4 5. Turn on the VIN input power supply, PS1, and increase the supply above twice the VOUT voltage setting plus 9V. (VPS1 > 2VOUT + 2V + VCS1 + VRS1 + Vammeter). For example, if VOUT is set to 3.3V, set PS1 above 3.3V * 2 + 9V or 15.6V. NOTE. Make sure that the input voltages do not exceed 60V. 6. Turn on and set the input current source to 4mA. Observe the voltage across the VIN and GND terminals and across the VOUT and GND terminals. The output ripple may also be observed using an oscilloscope with the probe connected as shown in Figure 2. 7. Increase the load on VOUT to about 7.4mA and observe the input current, input voltage and output voltage. 8. Increase the input current source from 4mA to 20mA. Observe the voltage across the VIN and GND terminals and across the VOUT and GND terminals. Adjust PS1 as per equation described in step 5 if needed. 9. Increase the load on VOUT to about 38mA and observe the output voltage. Observe the input current and input voltage as the load on VOUT is changed. 10. Refer to the LTC3255 data sheet for more details on how the LTC3255 operates. 11. When done, turn off all loads and power supplies. dc2041af DEMO MANUAL DC2041A SHUNT ENABLED + - + CS1 4mA TO 20mA CURRENT SOURCE - - + + + PS1 SUPPLY V > (2VOUT +24V) + VCS1 + VRS1 VMAX = 60V - - + - + - + L1 0mA TO 40mA Load DC2041 F03 - Figure 3. Proper Measurement Equipment Setup with Shunt Enabled dc2041af 5 DEMO MANUAL DC2041A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 C1 CAP CER, 1F, 25V, X7R 10% 0603 MURATA, GRM188R71E105KA12D 2 1 C2 CAP CER, 1F, 100V, X7R 10% 0805 TDK, C2012X7S2A105K 3 1 C3 CAP CER, 10F, 25V, 10% X7R 1206 MURATA, GRM31CR71E106KA12L 4 1 C5 CAP CER, 10pF, 50V, 5% NP0 0402 MURATA, GRM1555C1H100JA01D 5 1 C7 CAP CER, 0.1F, 16V, 10%, X7R 0402 MURATA, GRM155R71C104KA88D 6 1 R3 RES 1.1M, 1/16W, 1%, 0402 SMD VISHAY, CRCW04021M10FKED 7 1 R4 RES 383k, 1/16W, 1%, 0402 SMD VISHAY, CRCW0402383KFKED 8 1 R5 RES 215k, 1/16W, 1%, 0402 SMD VISHAY, CRCW0402215KFKED 9 1 R6 RES 133k, 1/16W, 1%, 0402 SMD VISHAY, CRCW0402133KFKED 10 1 R8 RES 220k, 1/16W, 5%, 0402 SMD VISHAY, CRCW0402220KJNED 11 2 R12 RES 121k, 1/16W, 1%, 0402 SMD VISHAY, CRCW0402121KFKED 12 1 U1 50mA STEP-DOWN CHARGE PUMP LINEAR TECH., LTC3255EMSE#PBF CAP CER 2.2F, 100V, 10%, X7R 1206 MURATA, GRM31CR72A225KA7 Additional Demo Board Circuit Components 13 1 C4 14 0 C6 CAP, 0603 SMD OPT 15 0 C8 CAP, 1206 SMD OPT 16 1 R1 RES 0.0, 1/8W, 0805 SMD VISHAY, CRCW08050000Z0EA 17 2 R2, R10 RES 10k, 1/16W, 5%, 0402 SMD VISHAY, CRCW040210K0JNED 18 0 R7 RES, 0402 SMD OPT 19 2 R9, R11 RES 10.0M, 1/16W, 5%, 0402 SMD VISHAY, CRCW040210M0JNED 20 0 R13, R14, R15 RES, 0805 SMD OPT Hardware: For Demo Board Only 21 4 E1, E2, E3, E4 TP, TURRET, 0.094", PBF MILL-MAX, 2501-2-00-80-00-00-07-0 22 4 E5, E6, E7, E8 TURRET, 0.061 DIA MILL-MAX, 2308-2-00-80-00-00-07-0 23 2 JP1, JP3 HEADER, 3 PIN, 1 ROW .079CC SAMTEC, TMM-103-02-L-S 24 3 JP1-JP3 SHUNT, 2mm SAMTEC, 2SN-KB-G 25 1 JP2 HEADER, 2.0mm, 2 x 5 SAMTEC, TMM-105-02-L-D 26 4 MH1-MH4 STAND-OFF, NYLON 0.375" TALL EYSTONE, 8832 (SNAP ON) 6 dc2041af GND EN GND VIN 4.0V - 48V E6 E5 E4 E1 10K 5% R10 C4 2.2uF 100V 1206 VIN OFF ON JP1 EN 0 0805 R1 1 2 3 VIN_P R2 10K 5% C6 OPT 100V 0603 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. R13 OPT 0805 OPT 0805 R15 OPT 0805 R14 VIN_P 4 7 6 C8 OPT 100V 1206 R11 10.0M 5% C7 0.1uF 16V OPTIONAL FILTER COMPONENTS JP3 SHUNT 1 ON 2 3 OFF VIN R9 10.0M 5% C2 1uF 100V 0805 10 SHUNT BIAS EN VIN 8 GND C+ U1 LTC3255EMSE 1 9 FB VOUT PGOOD C- 5 3 2 C3 10uF 25V 1206 R12 121k R3 1.1M C5 10pF 50V THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. CUSTOMER NOTICE 2. INSTALL SHUNTS AS SHOWN. 1. ALL RESISTORS ARE 0402, 1%, 1/16W ALL CAPACITORS ARE 0402, 10% R5 215k JP2 VOUT MARTY M. SCALE = NONE NC PCB DES. R7 OPT DATE: N/A SIZE LTC3255EMSE DEMO CIRCUIT 2041A 06 - 05 - 13 IC NO. GND PGOOD GND VOUT * 50mA DATE 6 - 5 - 13 SHEET 1 OF 1 2 REV. 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only E8 E7 E3 E2 APPROVED M. MERCHANT WIDE VIN RANGE FAULT PROTECTED 50mA STEP - DOWN CHARGE PUMP TECHNOLOGY R8 220K 5% PRODUCTION FAB 2 REVISION HISTORY DESCRIPTION REV TITLE: SCHEMATIC R6 133k * APP ENG. APPROVALS R4 383k 12V 5V 3.3V 2.5V OPT NOTE: UNLESS OTHERWISE SPECIFIED 11 GND 25V 0603 C1 1uF ECO DEMO MANUAL DC2041A Schematic Diagram dc2041af 7 DEMO MANUAL DC2041A 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 (c) 2004, Linear Technology Corporation 8 dc2041af Linear Technology Corporation LT 0913 * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com LINEAR TECHNOLOGY CORPORATION 2013