LTC3454 1A Synchronous Buck-Boost High Current LED Driver FEATURES DESCRIPTION n High Ef ciency: >90% Typical in Torch Mode, The LTC 3454 is a synchronous buck-boost DC/DC >80% in Flash Mode converter optimized for driving a single high power LED n Wide V Range: 2.7V to 5.5V at currents up to 1A from a single cell Li-Ion battery in- IN n Up to 1A Continuous Output Current put. The regulator operates in either synchronous buck, n 3.5% LED Current Programming Accuracy synchronous boost, or buck-boost mode depending on n Internal Soft-Start input voltage and LED forward voltage. P /P ef ciency LED IN n Open/Shorted LED Protection greater than 90% can be achieved over the entire usable n Constant Frequency 1MHz Operation range of a Li-Ion battery (2.7V to 4.2V). n Zero Shutdown Current LED current is programmable to one of four levels, includ- n Overtemperature Protection ing shutdown, with dual external resistors and dual enable n Small Thermally Enhanced 10-Lead (3mm 3mm) inputs. In shutdown no supply current is drawn. DFN Package A high constant operating frequency of 1MHz allows the use of small external components. The LTC3454 is offered APPLICATIONS in a low pro le (0.75mm) thermally enhanced 10-lead n Cell Phone Camera Flash (3mm 3mm) DFN package. n Cell Phone Torch Lighting L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Digital Cameras All other trademarks are the property of their respective owners. n PDAs n Misc Li-Ion LED Drivers TYPICAL APPLICATION High Ef ciency Torch/Flash LED Driver LED Power Ef ciency vs V IN L1 5H V IN 2.7V TO 4.2V 100 1-CELL Li-Ion 10F 10F I V SW1 SW2 V LED IN OUT I = 150mA 95 LED A D LED 90 EN2 EN1 I 85 I = 1A LED LED LED B C 0 0 0 (SHUTDOWN) 80 0 1 150mA EN1 (TORCH) 1 0 850mA 75 11 1A 70 EN2 (FLASH) 1MHz V C I SET1 BUCK-BOOST 65 T = 25C A R I 0.1F ISET1 EFFICIENCY = (V V )I /V I SET2 OUT LED LED IN IN 20.5k LTC3454 60 R ISET2 1% 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 GND (EXPOSED PAD) 3.65k LED: LUMILEDS LXL-PWF1 V (V) IN 1% L1: SUMIDA CDRH6D28-5RONC 3454 TA01b 3454 TA01a 3454fa 1 EFFICIENCY (%)LTC3454 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V , SW1, SW2, V Voltage ......................0.3V to 6V IN OUT V , EN1, EN2, I , I C SET1 SET2 EN1 1 10 SW1 Voltage .............................0.3V to (V + 0.3V) or 6V EN2 9 V 2 IN IN I 3 11 8 V SET1 C LED Peak Current ...................................................1.25A 4 7 I V SET2 OUT Storage Temperature Range ...................65C to 125C LED 5 6 SW2 Operating Temperature Range (Note 2)....40C to 85C DD PACKAGE Junction Temperature (Note 3) ............................. 125C 10-LEAD (3mm s 3mm) PLASTIC DFN T = 125C, = 40C/W JMAX JA EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3454EDD PBF LTC3454EDD TRPBF LBQX 10-Lead (3mm 3mm) Plastic DFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: