LT3955 60V LED Converter with IN Internal PWM Generator Fea T Descrip T n 3000:1 True Color PWM Dimming for LEDs The LT 3955 is a DC/DC converter designed to operate as n Wide V Range: 4.5V to 60V a constant-current source and constant-voltage regula- IN n Rail-to-Rail Current Sense Range: 0V to 80V tor. It features an internal low side N-channel MOSFET n Internal 80V/3.5A Switch rated for 80V/3.5A. The LT3955 is ideally suited for driv- n Programmable PWM Dimming Signal Generator ing high current LEDs, but also has features to make it n Constant Current (3%) and Constant-Voltage suitable for charging batteries and supercapacitors. The (2%) Regulation fixed frequency, current mode architecture results in n Accurate Analog Dimming stable operation over a wide range of supply and output n Drives LEDs in Boost, SEPIC, CUK, Buck Mode, voltages. A voltage feedback pin serves as the input for Buck-Boost Mode, or Flyback Configuration several LED protection features, and also makes it possible n Output Short-Circuit Protected Boost for the converter to operate as a constant-voltage source. n Open LED Protection and Reporting A frequency adjust pin allows the user to program the n Adjustable Switching Frequency: 100kHz to 1MHz frequency from 100kHz to 1MHz to optimize efficiency, n Programmable V UVLO with Hysteresis performance or external component size. IN n C/10 Indication for Battery Chargers The LT3955 senses output current at the high side or at n Low Shutdown Current: <1A the low side of the load. The PWM input can be configured n Thermally Enhanced 5mm 6mm QFN Package to self-oscillate at fixed frequency with duty ratio pro- grammable from 4% to 96%. When driven by an external a T signal, the PWM input provides LED dimming ratios of up to 3000:1. The CTRL input provides additional analog n High Power LEDs dimming capability. n Output Short-Circuit Protected Boost L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and n Battery and SuperCap Chargers True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the n property of their respective owners. Protected by U.S. Patents including 7199560, 7321203. Accurate Current Limited Voltage Regulators Typical a T 94% Efficiency 20W Boost LED Driver with Internal PWM Dimming 22H V IN PWM Dimming Waveforms at 5V TO 60V 4.7F 2.2F Various DIM Voltage Settings 499k V SW IN 2 5 EN/UVLO PGND V = 8V DIM 147k DC = 97.2% V ISP PWM REF 1M V = 3.87V LT3955 DIM 0.82 300mA I DC = 50% LED PWM CTRL 0.3A/DIV INTV CC ISN V = 1.47V DIM 165k DC = 10% PWM 1M 100k V = 0V DIM FB DC = 2.8% PWM VMODE 124k 20W LED STRING 3955 TA01b 0.5ms/DIV DIM DIM/SS 16.9k (CURRENT DERATED V = 24V IN FOR V < 9V) PWM SYNC IN V = 65V LED RT PWMOUT V GND GNDK INTV C CC 28.7k 10nF 350kHz INTV 5.1k CC 47nF 1F 4.7nF 300Hz 3955 TA01a NOTE: GND, GNDK AND SIGNAL LEVEL COMPONENTS MUST BE CONNECTED EXTERNALLY AS SHOWN. AN INTERNAL CONNECTION BETWEEN GNDK AND PGND PINS PROVIDES GROUNDING TO THE SUPPLY. 3955fb 1 For more information www.linear.com/LT3955 ion pplica ions pplica ion uresLT3955 a Te m aximum r a T p in c F T (Note 1) V , EN/UVLO ............................................................60V IN TOP VIEW ISP, ISN, SW .............................................................80V INTV ...................................................V + 0.3V, 9.6V CC IN PWMOUT ........................................................... (Note 2) 36 35 34 33 32 31 30 CTRL, VMODE ...........................................................15V SYNC 1 28 ISP EN/UVLO 2 27 ISN FB, PWM, SYNC .......................................................9.6V INTV 3 CC 37 V , V ......................................................................3V C REF GND GND 4 25 FB RT, DIM/SS ..............................................................1.5V 24 GND PGND, GNDK to GND .............................................0.5V V PWMOUT 6 23 IN Operating Ambient Temperature Range 38 (Notes 3, 4) ............................................ 40C to 125C SW 8 21 SW SW Maximum Junction Temperature .......................... 125C SW 9 20 SW NC 10 Storage Temperature Range .................. 65C to 150C 12 13 14 15 16 17 UHE PACKAGE 36-LEAD (5mm 6mm) PLASTIC QFN T = 125C, = 34C/W, = 3C/W JMAX JA JC EXPOSED PAD (PIN 37) IS GND, MUST BE SOLDERED TO GND PLANE EXPOSED PAD (PIN 38) IS SW, MUST BE SOLDERED TO SW PLANE o r Der i n F T LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3955EUHE PBF LT3955EUHE TRPBF 3955 36-Lead (5mm 6mm) Plastic QFN 40C to 125C LT3955IUHE PBF LT3955IUHE TRPBF 3955 36-Lead (5mm 6mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: