White LED Drivers Integrate LDOsAdvanced Analogic Technologies (AnalogicTech) announced its AAT2847, an integrated four-channel White LED (WLED) driver for portable systems operating off a single-cell Li-Ion/Polymer battery. The charge pump-based device also integrates two 200 mA Low Dropout (LDO) linear regulators, each with its own independent enable pin, to power ancillary system functions.The driver is built around a low-noise, tri-mode DC/DC charge pump converter that provides up to 120 mA of output current. Each of the device’s four channels supplies up to 30 mA of bias current for WLEDs. To ensure uniform display brightness, WLED backlight bias current matching is typically 0.5 percent. The device uses the company’s Advanced Simple Serial Control (AS2Cwire) digital interface to enable, disable and set the current for each backlight LED channel. Current level can be set across 52 levels including 16  current settings in three separate current scales – 30 mA, 20mA and 15 mA – as well as four low level current settings which go as low as 50 µA. 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 µA. The AAT2847 also integrates two LDOs. Each LDO is controlled by its own independent enable input and supplies up to 200 mA output current. Fixed or adjustable output versions are available. 

Advanced Analogic Technologies
408-737-4600, www.analogictech.com