Converter stores output and boosts its image
03 June 2008
The AAT1282 allows the use of white LEDs for high-intensity light for flash photography without battery drain.
An LED flash in portable applications has been problematic due to the high levels of battery curent, forward voltage and peak current required to produce the intensity required. AnalogicTech believes its AAT1282 2A flash LED driver will allow designers to use white LEDs, which deliver the high intensity light required without draining the still or video camera’s battery.
It integrates all of the circuitry required to charge the supercapacitor in a camera, to manage the in-rush current and to control LED current, to save development time, board space and component cost, claims the company.
The driver is designed to charge a supercapacitor with an integrated, fixed input current limiter to limit the battery current and to avoid large voltage drops. It has a high frequency boost converter with fixed input current limiting, dual output regulated current sinks and I²C control and uses a supercapacitor to store the output of a boost converter to deliver the required high peak current.
A high-current step-up converter has two output current sinks, which each provide a regulated 1A current. It operates over an input range of 2.7V to 5.5V and is designed for use with single cell, Li-Ion-powered devices. The two current souces share the output current and can be connected to apply the full output current into a single LED or can act as a separate source.
Current limit is set at 800mA but other values can be requested. By operating at 2MHz switching frequency, the converter is claimed to minimise the footprint of the end product as it allows a 1µHenry and 2.2µFarad ouptput capacitor.
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