AnalogicTech introduces dual, high-efficiency charge pump

May 4, 2005
Date Announced: 04 May 2005 Advanced Analogic Technologies Incorporated (AnalogicTech), a developer of innovative power management solutions, today introduced the AAT2805, a multi-function, high efficiency, dual charge pump that supports both white LED backlight and camera flash applications for portable systems that run on lithium-ion/polymer batteries. Featuring a light load mode with quiescent current as low as 80µA (typical), the AAT2805 minimizes power consumption during backlight operation. "Many portable devices using different display types, particularly transmissive displays, require some minimal level of backlighting at all times," explained Jan Nilsson, Vice President of Sales and Marketing at AnalogicTech. "The AAT2805 is super efficient in low-current mode, delivering extremely low quiescent current which allows designers to continually backlight their displays while consuming minimal amounts of power." Low Headroom Improves Efficiency The backlight charge pump in the AAT2805 drives up to four LEDs at a total output of 120mA. Current sinks may be operated individually or in parallel to drive higher current LEDs. To maximize power efficiency, the charge pump operates in 1X, 1.5X, and 2X modes. The device automatically selects the most efficient mode by comparing the forward voltage of each LED with the input voltage. Optimized current sinks minimize the voltage headroom required to drive each LED and help increase the amount of time the device stays in 1X mode before transitioning to 1.5X charge pump mode. That capability, in turn, helps to maximize power efficiency. Using AnalogicTech's Advanced Simple Serial Control™ (AS2Cwire™) digital interface, the device enables, disables, and sets current for each LED across a 16-level logarithmic scale. Four low-current settings allow operation in light load mode down to 50µA (typical). High Pulsed Current For flash applications, the AAT2805 integrates a charge pump doubler with a regulated output voltage. It is capable of delivering up to 120mA of continuous current for "movie-mode" or up to 250mA of pulsed current for camera flash. An independent enable pin maximizes power savings. A built-in thermal management circuit protects the device and soft-start circuitry prevents excessive inrush current during start-up. The AAT2805's high 1MHz charge pump switching frequency allows designers to support the device with extremely small ceramic capacitors. By eliminating the use of inductors, the AAT2805 also allows designers to build smaller, lower-profile systems. Price and Availability Available in a 16-pin, thermally-enhanced, lead-free TDFN44 package and qualified across the -40 to +85 degree C temperature range, the AAT2805 sells for $1.64 in 1,000-unit quantities.

Erik Ogren AnalogicTech +1 408 737 4600

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