DEMO MANUAL DC2361A LT3952EFE 2MHz 60V LED Driver with Internal 4A Switch DESCRIPTION Demonstration circuit DC2361A is a 2MHz 60V LED driver with internal 4A switch featuring the LT3952 monolithic LED driver. It accepts an input voltage from 8V to 28V (with transient to 36V) and boosts to a single string of LEDs up to 40V at 330mA. DC2361A features an integrated 4A switch, constant current and constant voltage output control as well as input current limit and monitoring. The LT3952 has a wide input voltage range down to 3V and up to 42V. It has adjustable switching frequency between 200kHz and 3MHz. It has an option for external frequency synchronization or spread spectrum frequency modulation. It has high PWM dimming capability from an external signal and can be PWM dimmed with an internally generated PWM oscillator and analog input signal. It can be analog dimmed with a control voltage on its control pin. LT3952 features both open LED and short LED (LED+ to GND) protection as well as fault output flags for each. Although DC2361A is assembled as a boost LED driver, it can be altered to be run as a buck mode, buck-boost mode or boost-buck LED driver. There is another demonstration circuit featuring LT3952 at 350kHz (DC2013A). DC2361A features an option to turn on spread spectrum by simply changing the position of a jumper from NO SPREAD to SPREAD or to EXTERNAL SYNC. Small ceramic input and output capacitors are used to save space and cost. The open LED overvoltage protection uses the IC’s constant voltage regulation loop to regulate the output to approximately 45V if the LED string is opened although it may reach 49V peak during transient from running LEDs to open. There is a protection diode from LED+ to GND to prevent negative ringing during a shortcircuit with long wires. There is undervoltage and overvoltage lockout that can be adjusted on the circuit with a few simple resistor choices. There is a small EMI filter on the input of DC2361A. This EMI filter has a ferrite bead and very small cap to reduce high frequency EMI. The PCB layout contains a small hot-loop for minimized very high frequency EMI. The EMI filter can be used by connecting to the ‘EMI VIN’ terminal. However, if the EMI filter is not needed, the input connection can be directly to the PVIN terminal. If the EMI filter is not used, it is recommended to remove the EMI filter if EMI measurements are being made from the PVIN terminal for base EMI testing. It can be replaced for EMI testing at the EMI VIN terminal. The LT3952 data sheet gives a complete description of the part, operation and applications information. The data sheet must be read in conjunction with this Demo Manual for demonstration circuit DC2361A. The LT3952EFE is assembled in a 28-lead plastic TSSOP (FE) package with a thermally enhanced ground pad. Proper board layout is essential for maximum thermal performance. See the Layout Considerations section. Design files for this circuit board are available at http://www.linear.com/demo/DC2361A 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. dc2361af 1 DEMO MANUAL DC2361A PERFORMANCE SUMMARY Specifications are at TA = 25°C PARAMETER CONDITIONS MIN Input Voltage PVIN and EMI VIN Range Operating VIN = PVIN VLED > 36V 8V TYP MAX 28V Switching Frequency R5 = 40.2k 2MHz ILED R1 = 0.75Ω 8.0V < PVIN < 36V VLED > 36V 333mA VLED range R2 = 1M R3 = 26.7k Open LED Voltage VOUT R2 = 1M R3 = 26.7k 43.5V Typical Efficiency (100% PWM DC) 90% Input Under Voltage Lockout (Falling Turn-Off) PVIN = 14V VLED = 40V ILED = 333mA R7 = 499k R8 = 71.5k R9 = 25.5k Input Under Voltage Lockout (Rising Turn-On) R7 = 499k R8 = 71.5k R9 = 25.5k 9.1V VISMON Operating ILED = 330mA 1.0V Peak Switch Current Limit Operating 4A Demonstration circuit 2361A is easy to set up to evaluate the performance of the LT3952 Follow the procedure below: 5. Release the EN/UVLO-to-GND connection. PVIN 40V 7.6V QUICK START PROCEDURE 1. Connect a string of LEDs that will run with forward voltage less than or equal to 40V (at 330mA), but greater than PVIN, to the LED+ and GND terminals on the PCB as shown in Figure 1. 6. Observe the LED strings running at the programmed LED current. 2. Connect the EN/UVLO terminal to GND. 7. To change the brightness with analog dimming, simply attach a voltage source to the CTRL terminal and set the voltage between 0V and 1.5V. See data sheet for details. 3. With power off, connect the input power supply to the EMI VIN (or PVIN) and GND terminals. Make sure that the DC input voltage will not exceed 28V (or VLED). 8. To change brightness with external PWM dimming, attach a 3V rectangular waveform with varying duty cycle to the PWM terminal. 4. Turn the input power supply on and make sure the voltage is between 8V and 28V (or VLED) for proper operation. 9. To enable spread spectrum frequency modulation, simply change the position of the shunt on the SYNC/ SPRD jumper to the SPREAD SPECTRUM position. dc2361af 2 DEMO MANUAL DC2361A DEMO CIRCUIT OPTIONS Demonstration circuit 2361A can be adjusted for higher or lower output voltage, different LED current, or different topology. The following options are for simple changes to the demonstration circuit. The data sheet gives more information regarding designing with the LT3952. For more information, see the data sheet for details or contact Linear Tech customer support. regulator. Output voltage should remain below 60V when used as a constant voltage device. MAXIMUM LED VOLTAGE A change in LED current or input voltage may lead to higher or lower maximum switch current. The maximum switch current for this converter is 4A and is fixed internally. DC2361A is set for 44V of overvoltage protection and the maximum LED string voltage used on the standard build should be 40V. LT3952 output voltage can be set higher with an adjustment to the OVP resistors. When raising output voltage, be sure not to violate the maximum duty cycle limit at 2MHz (or adjusted frequency), the 60V abs max output voltage of the part (including open LED output overshoot), and 4A peak switch current limit at low VIN. See data sheet for details. CURRENT OR VOLTAGE REGULATION The LT3952 can be used for constant current or voltage regulation. If the load placed on the LED+ to GND terminals allows VOUT to climb high enough for V(ISP-ISN)=1.2V, then the voltage regulation loop of the converter takes over. In this case, the compensation for a given channel should be adjusted for proper use as a constant voltage regulator. The IC can be used as a boost or SEPIC constant voltage LED CURRENT LED current on DC2361A is set for 330mA with 0.75Ω resistor R1. For a different maximum LED current, change this resistor. 250mV/RLED = ILED. OVERVOLTAGE PROTECTION Overvoltage protection is set with the resistor pair R2 and R3 for the boost topology. For buck mode, buck-boost mode, and boost-buck see data sheet for details how to set the feedback resistors. Note that R19, R20, R21, and Q1 are provided as optional placeholders on the demonstration circuit for simple feedback resistor changes for these topologies. UNDERVOLTAGE AND OVERVOLTAGE LOCKOUT UVLO and OVLO can be adjusted by changing the values of R7, R8 and R9. Resistors R10 and R11 are available for setting UVLO and OVLO separately. dc2361af 3 DEMO MANUAL DC2361A DEMO CIRCUIT OPTIONS – ILED + CONNECT POWER TO EITHER PVIN OR TO EMI VIN IIN + – VOUT – + POWER SUPPLY + – + VIN – + – + – OPTIONAL SHUTDOWN SELECT JPI SETTING 3V 3V 0V 0V EXTERNAL SYNC OPTION 0V 3V OPTIONAL ANALOG DIMMING OPTIONAL EXTERNAL PWM Figure 1. Test Procedure Setup Drawing for DC2361A Figure 2. DC2361A 12VIN 120Hz PWM Dimming Waveforms at Different PWM Duty Cycles with 5000:1 in Bold. ILED Waveform (200mA/Div) Is on the Bottom (with 40V LED String) and IL1 Waveform (2A/Div) Is on the Top. dc2361af 4 DEMO MANUAL DC2361A DEMO CIRCUIT OPTIONS 0.400 0.300 0.250 0.200 0.150 0.100 0.050 0.000 6 7 8 9 10 PVIN (V) 11 12 13 14 24 25 26 27 PVIN (V) 28 29 30 Figure 3. DC2361A UVLO and OVLO Falling and Rising 100% 95% EFFICIENCY (%) LED CURRENT (A) 0.350 90% 85% 80% 75% 70% 0 5 10 15 PVIN (V) 20 25 30 Figure 4. DC2361A Efficiency at Maximum ILED vs PVIN with 40V LEDs (at 330mA) dc2361af 5 DEMO MANUAL DC2361A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER MURATA, GRM31CR61H106KA12L Required Circuit Components 1 1 C1 CAP., 10μF, X5R, 50V, 10%, 1206 2 1 C2 CAP., 1μF, X7R, 50V, 10%, 0805 MURATA, GRM21BR71H105KA12L 3 1 C3 CAP., 0.1μF, X7R, 10V, 10%, 0402 MURATA, GRM155R71A104KA01D 4 1 C4 CAP., 1000pF, X5R, 10V, 10%, 0402 MURATA, GRM155R61A102KA01D 5 1 C5 CAP., 2.2μF, X5R, 6.3V, 10%, 0603 MURATA, GRM188R60J225KE19D 6 1 C6 CAP., 4.7μF, X7R, 50V, 10%, 1206 MURATA, GRM31CR71H475KA12L 7 1 D1 DIODE, SCHOTTKY, RECTIFIER, 60V, 1A,SOD-123F NXP, PMEG6010CEH,115 8 1 L1 IND., PWR., 2.2μH, 20%, 4020 Würth Elektronik, 74437324022 9 1 M1 XSTR., MOSFET, P-CH, 60V, SOT-23 VISHAY, Si2309CDS-T1-GE3 10 1 R1 RES., 0.75Ω, 1/2W, 1%, 1206 SUSUMU, RL1632R-R750-F 11 1 R2 RES., 1M, 1/10W, 1%, 0603 VISHAY, CRCW06031M00FKEA PANASONIC, ERJ3EKF1004V 12 1 R3 RES., 26.7k, 1/16W, 1%, 0402 VISHAY, CRCW040226K7FKED 13 1 R4 RES., 10k, 1/16W, 5%, 0402 VISHAY, CRCW040210K0JNED 14 1 R5 RES., 40.2k, 1/16W, 1%, 0402 VISHAY, CRCW040240K2FKED 15 1 U1 I.C., LED Driver, TSSOP-28 LINEAR TECH., LT3952EFE#PBF Optional Electrical Components 1 1 C7 CAP., 0.47μF, X5R, 10V, 10%, 0402 MURATA, GRM155R61A474KE15D 2 1 C8 CAP., ALUM. ELECT.,33μF, 50V, 20%, D8 CASE PANASONIC, EEHZA1H330XP 3 1 C9 CAP., 0.1μF, X7R, 10V, 10%, 0402 MURATA, GRM155R71A104KA01D 4 0 C10, C12(OPT) CAP., OPTION, 1206 OPT. 5 0 C11, C13(OPT) CAP., OPTION, 0402 6 1 D2 DIODE, RECTIFIER, 100V, 1A, SMA DIODES INC., ES1B-13-F 7 1 FB1 IND., BEAD, CHIP, 100Ω, ±25%, 0805 TDK, MPZ2012S101AT 8 0 Q1(OPT) XSTR., OPTION, PNP, SOT-23 OPT. 9 1 R6 RES., SENSE, 0.015Ω, 1W, 1%, 1206 PANASONIC, ERJ8BWFR015V 10 1 R7 RES., 499k, 1/16W, 1%, 0402 VISHAY, CRCW0402499KFKEA 11 1 R8 RES., 71.5k, 1/16W, 1% 0402 VISHAY, CRCW040271K5FKED 12 1 R9 RES., 25.5k, 1/16W, 1% 0402 VISHAY, CRCW040225K5FKED 13 0 R10, R11, R15, R16, R19-R23(OPT) RES., OPTION, 0402 OPT. 14 3 R12, R13, R14 RES., 100k, 1/16W, 1%, 0402 VISHAY, CRCW0402100KFKED NIC, NRC04F1003TRF 15 0 R17(OPT) RES., OPTION, 0603 OPT. 16 1 R18 RES., 0Ω, 1/10W, 0603 VISHAY, CRCW06030000Z0EA NIC, NRC06ZOTRF 1 7 E1-E7 TEST POINT, TURRET, .094" MTG. HOLE MILL-MAX, 2501-2-00-80-00-00-07-0 2 8 E8-E15 TEST POINT, TURRET, .064" MTG. HOLE MILL-MAX, 2308-2-00-80-00-00-07-0 3 1 JP1 CONN., HEADER, 2 × 3, 2mm Würth Elektronik, 62000621121 4 1 XJP1 SHUNT, 2mm Würth Elektronik, 60800213421 Hardware dc2361af 6 DEMO MANUAL DC2361A SCHEMATIC DIAGRAM dc2361af 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. 7 DEMO MANUAL DC2361A 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 dc2361af 8 Linear Technology Corporation LT 0615 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2015