DEMO MANUAL DC1930A LT3744 High Current Synchronous Inverting Buck-Boost LED Driver DESCRIPTION Demonstration circuit 1930A is a high current synchronous inverting buck-boost LED driver featuring the LT®3744. The unique drive stage used on the LT3744 allows the anodes of three LEDs to be connected together for better heat sinking in both the step-down configuration and the inverting buckboost configuration. The pros and cons of each configuration can be found in the data sheet. This demonstration circuit 1930A is for customers to test the inverting buck-boost configuration. The step-down configuration is shown in a separate demonstration circuit DC2339A. The components are optimized for the efficiency, thermal and PWM dimming for a 12V input. Each of the three outputs is up to 5V, 12A with a 6.05V maximum output voltage limit. The PWM1, PWM2 and PWM3 pins are set to low by default. A DC or PWM signal is required to connect to at least one of the PWM pins to enable the circuit. At any giving time, output current only passes through one LED determined by settings of PWM pins. The CTRL1, CTRL2 and CTRL3 pins can be adjusted to provide accurate analog dimming down to 20:1 ratio. The input voltage range for the LT3744 to operate is from 3.3V to 36V. However, to maintain the output current regulation in an inverting buck-boost regulator, the actual input voltage range is determined by the load current, voltage, the maximum duty cycle, etc. For a 5V, 12A load, the demo board operating input range should limit to 7V to 30V at room temperature. The load to be used with this demo board is high current LEDs or laser diodes. Smaller PERFORMANCE SUMMARY SYMBOL LEDs may not be able to handle the high current, even for a short period of time. It is necessary to mount the LED load on a proper heat sink. A fan may become necessary to avoid exceeding LED’s maximum temperate rating. The typical efficiency of the demo board is 89.3% from a 12V input to 4V, 12A load. If an efficiency measurement is needed in an application, the output voltage must be measured at the output capacitors instead of the LED load. This prevents cable loss from being counted as loss of the board. The demo circuit DC1930A achieves fast current rise time from 0A to 12A in 5μs. To see the real rise time, wires between the LED and the board should be as short as possible to minimize the wire inductance and resistance. It is recommended to measure the voltage across R32 with a short 50Ω coax cable directly into a BNC connector on the oscilloscope. Figure 1 shows the current rise time. The current can be calculated from the measured voltage. A current probe adds more delays to the rise time so using a current probe is not recommended unless rise time is not a concern. The LT3744 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 1930A. Design files for this circuit board are available at http://www.linear.com/demo/DC1930A 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 = 25°C PARAMETER CONDITIONS PVIN* Input Supply Voltage LED Voltage = 5V VLED+ to VLED– Maximum Output Voltage IOUT Output Current FSW Switching Frequency MIN 7 Efficiency at DC MAX 30 6.05 CTRL1, CTRL2, CTRL3 = 1.5V 11.4 270 VIN = 12V, IOUT = 12A, VOUT = 4V *The board operating voltage range is narrower than the IC operating range in an inverting buck-boost configuration. EFF TYP UNITS V V 12 12.6 A 300 330 kHz 89.3 % dc1930af 1 DEMO MANUAL DC1930A DESCRIPTION LED CURRENT 5A/DIV SW VOLTAGE 5V/DIV DC1930A F01 Figure 1: DC1930A Current Rise Time: VIN = 12V, LED Voltage = 4.2V when ON. Total LED Current = 12A QUICK START PROCEDURE Demonstration circuit 1930A is easy to set up to evaluate the performance of the LT3744. Refer to Figure 2 for proper measurement equipment setup and follow the procedure below: 1. With power off, connect the input power supply to PVIN and GND. Note: make sure PVIN is below 30V. 2 2.With power off, connect the LED load to VLED+ and proper LED1–, LED2–, LED3– according to the setting of the PWM pins. 3. Turn on the power at the input. 4. Carefully evaluate other design parameters as needed. dc1930af DEMO MANUAL DC1930A QUICK START PROCEDURE Figure 2. Proper Measurement Equipment Setup dc1930af 3 DEMO MANUAL DC1930A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 4 C1, C2, C24, C25 CAP., X7R, 10µF, 50V, 10%, 1210 MURATA, GRM32ER71H106KA12L 2 1 C4 CAP., ALUM., ELECT., 56µF, 50V SUN ELECTRONIC INDUSTRIES CORP., 50HVT56M 3 1 C6 CAP., X7R, 0.22μF, 25V, 10% 0603 MURATA, GRM188R71E224KA88D 4 1 C7 CAP., X7R, 1μF, 50V, 10% 0805 AVX, 08055C105KAT2A 5 1 C8 CAP., X7R, 22μF, 6.3V, 20% 0805 AVX, 08056D226MAT2A 6 1 C9 CAP., X5R, 10μF, 25V, 20% 1206 AVX, 12063D106MAT2A 7 3 C11, C12, C16 CAP., POSCAP, 470µF, 6.3V, D4D PANASONIC, 6TPF470MAH 8 1 C14 CAP., X5R, 2.2μF, 25V, 10% 0603 MURATA, GRM188R61E225KA12D 9 1 C18 CAP., X7R, 10nF, 25V, 10% 0603 AVX, 06033C103KAT2A 10 5 C19, C26-C29 CAP., X7R, 1nF, 25V, 10% 0603 AVX, 06033C102KAT2A 11 3 C21, C22, C23 CAP., X7R, 33nF, 25V, 10% 0603 MURATA, GRM188R71E333KA01D 12 1 D1 SCHOTTKY RECTIFIER, 40V, SOD523 NXP, PMEG4002EB 13 2 D3, D4 DIODE, BAT54A SOT23 DIODES INC., BAT54A-7-F 14 1 D5 DIODE, SBR1A40S3 SOD-323 DIODES INC., SBR1A40S3-7 15 1 L1 INDUCTOR, 0.82μH WURTH ELEKTRONIK, 744355182 16 2 Q1, Q2 N-CH., 40-V, PG-TDSON-8 INFINEON, BSC035N04LS G 17 2 Q3, Q5 N-CH., 40-V, PG-TDSON-8 INFINEON, BSC026N04LS 18 3 Q4, Q6, Q7 N-CH., 12-V, POWERPAK SO-8 VISHAY, Si7234DP-T1-GE3 19 3 Q8-Q10 N-CH., 40-V, PG-TDSON-8 FL INFINEON, BSC010N04LS 20 9 R3, R6, R7, R8, R10, R20, R21, R22, R23 RES., CHIP., 100k, 1/10W, 1%0603 VISHAY, CRCW0603100KFKEA 21 9 R1, R4, R12, R13, R29-R31, R33, R36 RES., CHIP., 0Ω, 1/10W, 0603 VISHAY, CRC06030000Z0EA 22 1 R5 RES., CHIP., 0.003Ω, 3W, 1%, KRL6432 SUSUMU, KRL6432E-M-R003-F 23 1 R14 RES., CHIP., 4.02k, 1/10W, 1% 0603 VISHAY, CRCW06034K02FKEA 24 1 R16 RES., CHIP., 82.5k, 1/10W, 1% 0603 VISHAY, CRCW060382K5FKEA 25 3 R17, R18, R19 RES., CHIP., 309k, 1/10W, 1% 0603 VISHAY, CRCW0603309KFKEA 26 1 R25 RES., CHIP., 143k, 1/10W, 1% 0603 VISHAY, CRCW0603143KFKEA 27 1 R27 RES., CHIP., 1k, 1/10W, 1% 0603 VISHAY, CRCW06031K00FKEA 28 1 R32 RES., CHIP., 0.005Ω, 3W, 1%, KRL6432 SUSUMU, KRL6432D-M-R005-F 29 1 U1 I.C. LT3744EUHE 36-PIN, UHE LINEAR TECH., LT3744EUHE#PBF Additional Demo Board Circuit Components 1 0 C5 (OPT) CAP., ALUM., ELECT. 2 0 C10, C13, C15 (OPT) CAP., D4D 3 0 C17 (OPT) CAP., 0603 4 0 D2 (OPT) DIODE, DI123 5 0 R2, R9 (OPT) RES., CHIP., 0603 Hardware For Demo Board Only 1 16 E1-E16 TESTPOINT, TURRET, 0.094" PBF MILL-MAX, 2501-2-00-80-00-00-07-0 2 8 J1-J8 JACK BANANA KEYSTONE, 575-4 3 4 (STAND-OFF) STAND-OFF, NYLON 0.50” (SNAP ON) WURTH ELEKTRONIK, 702935000 4 dc1930af 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 E1 C27 1nF SYNC PWM3 PWM2 PWM1 CTRL3 CTRL2 CTRL1 EN/UVLO R21 100K R22 100K 2 R8 R16 C26 R9 E8 1nF 82.5K OPT 100K 0805 C7 1uF 50V 7 5 4 2 6 3 1 36 E9 R17 309K E7 E14 5 D5 SBR1A40S3 1 143K (300kHz) R25 13 14 11 VIN RT SS FAULT SYNC PWM3 PWM2 PWM1 CTRL3 CTRL2 CTRL1 CTRLT VREF EN/UVLO VIN U1 LT3744EUHE C24 10uF 50V 1210 1. ALL RESISTORS ARE 0603. ALL CAPACITORS ARE 0603. NOTE: UNLESS OTHERWISE SPECIFIED R19 309K R23 100K C18 10nF 10 9 R20 100K C14 2.2uF SGND 100K R3 R33 0 8 C29 1nF R7 100K OPT R2 C1 C2 10uF 50V 1210 E13 R18 309K R10 100K C4 56uF,50V 50HVT56M E12 C28 1nF R6 100K E16 E15 E2 E10 E6 E4 E11 SGND SGND SGND J2 BANANA JACK SGND + 4 C25 10uF 50V 1210 C5 OPT C23 33nF C22 33nF C21 33nF R31 0 R30 0 R29 0 + 29 J1 BANANA JACK 12 SGND 31 0 ISN ISP VF NEG BG SW INTVCC LED_ISN LED_ISP FB PWM_OUT3 PWM_OUT2 C8 22uF 6.3V 0805 C6 0.22uF 4 PWM3 15 16 17 PWM2 0 R13 PWM1 0 R12 23 4 25 C17 OPT R36 0 27 21 22 24 32 Q3 Q5 BSC026N04LS 30 34 D1 PMEG4002EB R4 0 R1 PWM_OUT1 BOOST 2 1 5 6 7 8 L1 0.82uH 3 D3-1 BAT54A D2 OPT DI123 KRL6432 R5 0.003 Q1 Q2 BSC035N04LS G 744355182 1 2 3 5 6 7 8 1 2 3 PVIN 3 D3-2 BAT54A 4 2 2 1 3 * + Q6 4 2 D4-2 BAT54A 3 2 Si7234DP 8 7 5 6 C10 OPT C11 470uF 1 3 PVIN 3.3V - 36V 3 1 + 2 R32 0.005 KRL6432 4 2 D4-1 BAT54A 3 1 Si7234DP Q4 8 7 5 6 C15 OPT C12 470uF 2 1 3 3 + Si7234DP Q7 8 7 5 6 C13 OPT C16 470uF R27 1K R14 4.02K 4 Q8 C19 1nF J6 LED1- LED+ J3 BSC010N04LS PWM1 C9 10uF 1206 5 6 7 8 1 2 3 D 4 4 Q9 BSC010N04LS PWM2 J7 LED2- LED+ J4 1 5 6 7 8 1 4 J8 LED3- LED+ J5 Q10 BSC010N04LS PWM3 1 2 3 * SEE DEMO MANUAL VEE 28 VEE 26 VEE 33 VEE 35 VEE 37 VC1 20 TG VC2 19 VC3 18 5 6 7 8 1 2 3 5 E5 E3 VEE LED+ A B C D DEMO MANUAL DC1930A SCHEMATIC DIAGRAM dc1930af 5 DEMO MANUAL DC1930A 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 dc1930af Linear Technology Corporation LT 1215 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2015