LT3954 40V LED Converter with IN Internal PWM Generator FEATURES DESCRIPTION n 3000:1 True Color PWM Dimming for LEDs The LT 3954 is a DC/DC converter designed to operate as n Wide V Range: 4.5V to 40V a constant-current source and constant-voltage regulator. IN n Rail-to-Rail Current Sense Range: 0V to 40V It features an internal low side N-channel MOSFET rated n Internal 40V/5A Switch for 40V/5A. The LT3954 is ideally suited for driving high n Programmable PWM Dimming Signal Generator current LEDs, but also has features to make it suitable n Constant Current (3%) and Constant-Voltage for charging batteries and supercapacitors. The fixed (2%) Regulation frequency, current mode architecture results in stable n Accurate Analog Dimming operation over a wide range of supply and output voltages. n Drives LEDs in Boost, SEPIC, CUK, Buck Mode, A voltage feedback pin serves as the input for several Buck-Boost Mode, or Flyback Configuration LED protection features, and also makes it possible for n Output Short-Circuit Protected Boost 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 LT3954 senses output current at the high side or at n Low Shutdown Current: <1A the low side of the load. The internal PWM generator can n Thermally Enhanced 5mm 6mm QFN Package be configured to self-oscillate at fixed frequency with duty ratio programmable from 4% to 96%. When driven by an APPLICATIONS external signal, the PWM input provides LED dimming n High Power LEDs ratios of up to 3000:1. The CTRL input provides additional n Output Short-Circuit Protected Boost analog dimming capability. n Battery and SuperCap Chargers L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the n Accurate Current Limited Voltage Regulators property of their respective owners. Protected by U.S. Patents including 7199560, 7321203. TYPICAL APPLICATION 95% Efficiency 20W Boost LED Driver with Internal PWM Dimming 22H V IN 5V TO 30V 4.7F 499k 4.7F V SW IN 3 PWM Dimming Waveforms at PGND EN/UVLO Various DIM Voltage Settings 147k V ISP REF 1M LT3954 V = 8V 0.38 DIM 650mA CTRL DC = 97.2% PWM INTV CC ISN V = 3.87V 165k DIM I DC = 50% LED 1M PWM 100k 20W LED STRING 0.65A/DIV V = 1.47V DIM FB (CURRENT DERATED VMODE DC = 10% PWM 124k FOR V < 9V) IN 37.4k DIM DIM/SS V = 0V DIM PWM SYNC DC = 2.8% PWM 3954 TA01b RT PWMOUT 0.5ms/DIV V = 24V V GND GNDK INTV C CC IN 28.7k V = 32V 10nF LED 350kHz INTV 5.1k CC 3954 TA01a 47nF 1F 4.7nF 300Hz 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 3954fa 1 For more information www.linear.com/3954LT3954 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) V , EN/UVLO ............................................................40V IN TOP VIEW ISP, ISN, SW .............................................................40V 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 6 23 PWMOUT 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 = 34C/W, = 3C/W 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 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3954EUHE PBF LT3954EUHE TRPBF 3954 36-Lead (5mm 6mm) Plastic QFN 40C to 125C LT3954IUHE PBF LT3954IUHE TRPBF 3954 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: