LTC3454 Datasheet | Linear Technology

1A Synchronous Buck-Boost High Current LED Driver Features n High Efficiency: >90% Typical in Torch Mode, >80% in Flash Mode n Wide VIN Range: 2.7V to 5.5V n Up to 1A Continuous Output Current n 3.5% LED Current Programming Accuracy n Internal Soft-Start n Open/Shorted LED Protection n Constant Frequency 1MHz Operation n Zero Shutdown Current n Overtemperature Protection n Small Thermally Enhanced 10-Lead (3mm × 3mm) DFN Package APPLICATIONS n Cell Phone Camera Flash n Cell Phone Torch Lighting n Digital Cameras n PDAs n Misc Li-Ion LED Drivers DESCRIPTION The LTC®3454 is a synchronous buck-boost DC/DC converter optimized for driving a single high power LED at currents up to 1A from a single cell Li-Ion battery input. The regulator operates in either synchronous buck, synchronous boost, or buck-boost mode depending on input voltage and LED forward voltage. PLED/PIN efficiency greater than 90% can be achieved over the entire usable range of a Li-Ion battery (2.7V to 4.2V). LED current is programmable to one of four levels, including shutdown, with dual external resistors and dual enable inputs. In shutdown no supply current is drawn. A high constant operating frequency of 1MHz allows the use of small external ponents. The LTC3454 is offered in a low profile (0.75mm) thermally enhanced 10-lead (3mm × 3mm) DFN package. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION High Efficiency Torch/Flash LED Driver VIN 2.7V TO 4.2V 1-CELL Li-Ion 10μF L1 5μH VIN SW1 SW2 VOUT 10μF ILED EN2 EN1 ILED 0 0 0 (SHUTDOWN) 0 EN1 (TORCH) 1 1 150m A 0 850m A 1 1 1A 1MHz BUCK-BOOST EN2 (FLASH) ISET1 0.1μF LED: LUMILEDS LXL-PWF1 L1: SUMIDA CDRH6D28-5RONC ISET2 LTC3454 GND (EXPOSED PAD) RISET2...