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AAT2801

Multi-Mode Charge Pump for White LED Backlight and Flash Applications General Description Features

ChargePump

™

The AAT2801 is a member of AnalogicTech's TotalPower Management IC™ (TPMIC™) product family. It has a dual charge pump architecture designed to support both the white LED backlight and flash appli- cations for systems operating with Lithium-Ion bat- teries. The backlight charge pump provides power required to drive up to four LEDs. To maximize power efficiency, it automatically selects 1X, 1.5X, or 2X mode. The device produces current levels up to 30mAon each of its four current source outputs. AnalogicTech's Simple Serial Control™ (S •V

IN

Range: 2.7V to 5.5V•Dual Charge Pump—Flash: Charge Pump Doubler —Backlight: Tri-Mode Charge Pump•Drives Low-V

F

and High-V

F

LEDs•Up to Four 30mAOutputs •32-Position Logarithmic Scale with DigitalControl•Low Noise Constant Frequency Operation •1MHz Switching Frequency •AutoBias Technology •Regulated 4.5/5.0 Volts V

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Cwire™)interface is used to enable, disable, and set the LED drive current with a 32-level logarithmic scale LED brightness control. The flash charge pump is a charge pump doublerwith a regulated output voltage. It is designed to deliver 120mAof continuous current and up to 250mAof pulsed current. It has an independent enable pin for improved power savings.The AAT2801 is equipped with AnalogicTech’sAutoBias™ technology which allows individual LEDs to be powered either by charge pump or battery input, determined internally and automatically to maximize the power efficiency even with a large dif- ference in LEDforward voltage.The AAT2801 has thermal protection and built-insoft-start circuitry. Ahigh charge pump switching fre- quency enables the use of very small external capac- itors. The AAT2801 is available in the 16-pin TDFN44 package.

OUT_FLASH

•Up to 250mAof Current for Flash •Automatic Soft Start •No Inductors •I

Q

<1µAin Shutdown•Available in 16-pin TDFN44 Package Applications •Display Modules •Mobile Phones •PDAs •Smart Phones Typical Application

C11 C21 C31 µ F µ F µ F
+ C1
- C2
+ C2
- C3
+ C3
- INCPC1 OUT_FLSH C
F 1 µ F R
B V
IN C
IN C
CP 1 µ F 1 µ F

AAT2801

D2GND

BacklightFlash LED

EN/SET D4 D3 D2 D1 Flash EnableEN/SETEN_FLSHD1D3D4

2801.2006.04.1.3

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