AAT2803
Six-Channel White LED Backlight
Charge Pump with Flash
™
ChargePump
General Description
Features
TheAAT2803 is a dual charge pump designed to sup-
port both white LED backlight and flash applications
for systems operating with lithium-ion/polymer batter-
ies. The backlight charge pump is capable of driving
up to six LEDs at a total of 180mA. The current sinks
may be operated in group or in parallel for driving
higher current LEDs. To maximize power efficiency,
the charge pump operates in 1X, 1.5X, or 2X mode,
where the mode of operation is automatically select-
ed by comparing the forward voltage of each LED
with the input voltage. AnalogicTech's AS2Cwire™
(Advanced Simple Serial Control™) serial digital input
is used to enable, disable, and set current for each
LED with a 16-level logarithmic scale plus four low-
current settings down to 50μA for optimized efficien-
cy, with a low housekeeping current of only 50μA.
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VIN Range: 2.7V to 5.5V
Dual Charge Pump:
— Flash: Charge Pump Doubler
— Backlight: Tri-Mode Charge Pump
Backlight Charge Pump:
— Programmable Current With Single GPIO
— 16 Current Steps
— 15/20/30mA Max Current
— Four Low Current Settings
— Individual Main/Sub-Group Control
— Low IQ (50μA) for Low-Current Mode
— Drives Six Channels of LEDs
Flash Charge Pump:
— Regulated VOUT_FL 4.5/5.0 Volts
— Up to 300mA of Current for Flash
1MHz Constant Switching Frequency
Independent Backlight/Flash Control
Built-In Thermal Protection
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The flash charge pump is a charge pump doubler
with a regulated output voltage. It is designed to
deliver 120mA of continuous current and up to
300mA of pulsed current. It has an independent
enable pin for improved power savings.
Built-In Auto-Disable for Open Circuit
Automatic Soft Start
IQ <1μA in Shutdown
Available in QFN44-24 Package
The AAT2803 is equipped with built-in protection,
short-circuit, and auto-disable for load short-circuit
condition. Built-in soft-start circuitry prevents exces-
sive inrush current during start-up. A low-current
shutdown feature disconnects the load from VIN and
reduces quiescent current to less than 1μA.
Applications
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Color (RGB) Lighting
Programmable Current Sink
White LED Backlighting
The AAT2803 is available in a Pb-free, space-saving,
thermally enhanced 24-pin 4x4mm QFN package
and is rated over the -40°C to +85°C temperature
range.
White Photo Flash for Digital Still Cameras
Typical Application
C1
C2
C3
1μF
1μF
1μF
C1+ C1- C2+ C2- C3+ C3-
Flash
VOUT
VIN
COUT
1μF
VIN
CIN
1μF
Backlight
AAT2803
COUT
1μF
D1
D6
D4
D3
D2
D5
EN_FL
ENFL
D6
D5
D4
D3
D2
EN/SET
EN/SET
D1
GND
2803.2006.12.1.6
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