描述 Description

The AT8854 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-lon 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 components. The AT8854 is offered in a low profile (0.75mm) thermally enhanced 10-lead(3mm×3mm) DFN package.

特性 Features

? High Efficiency: >90% Typical in Torch Mode, >80% in Flash Mode.
? Wide VIN Range: 2.7V to 5.5V
? Up to 1A Continuous Output Current
? 3.5% LED Current Programming Accuracy
? Internal Soft-Start
? Open/Shorted LED Protection
? Constant Frequency 1MHz Operation
? Zero Shutdown Current
? Over temperature Protection
? Small Thermally Enhanced 10-lead (3mm×3mm) DFN Package

應(yīng)用 Application

? Cell Phone Camera Flash
? Cell Phone Torch Lighting
? Digital Cameras
? PDAs
? Misc Li-lon LED Drivers