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WLED driver has two LDOs for portable systems

Posted: 13 Dec 2007 ?? ?Print Version ?Bookmark and Share

Keywords:WLED driver? white LED driver? portable systems?

Advanced Analogic Technologies Inc. has released a highly integrated four-channel white LED (WLED) driver for portable systems operating off a single-cell Li-ion/polymer battery. The AAT2847 charge pump-based device also integrates two 200mA low dropout (LDO) linear regulators, each with its own independent enable pin, to power ancillary system functions. Each LDO supplies up to 200mA output current. Fixed or adjustable output versions are available.

The AAT2847 is built around a low-noise, tri-mode DC/DC charge pump converter that delivers up to 120mA of output current. Each of the device's four channels supplies up to 30mA of bias current for WLEDs. To ensure uniform display brightness, WLED backlight bias current matching is typically 0.5 percent. Each LED channel features embedded short circuit protection and auto disable functionality. A low shutdown current feature disconnects the load from the input and reduces quiescent current to less than 1?A.

The device uses AnalogicTech's Advanced Simple Serial Control (AS2Cwire) digital interface to enable, disable and set the current for each backlight LED channel. Current settings can be set across 52 levels including sixteen current settings in three separate current scales30mA, 20mA and 15mAas well as four low-level current settings as low as 50?A.

Available in a 20-pin, 3mm x 4mm x 0.75mm TQFN package, the AAT2847 is qualified across the -40C to +85C temperature range.

Pricing starts at $1.09 in quantities of 1,000.

- Gina Roos

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