AAT2803 Datasheet, PDF (1/16 Pages) Advanced Analogic Technologies – Six-Channel White LED Backlight Charge Pump with Flash

General Description
The AAT2803 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.
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.
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 V_IN and
reduces quiescent current to less than 1μA.
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.
Typical Application
C1
C2
C3
1μF 1μF
1μF
AAT2803
Six-Channel White LED Backlight
Charge Pump with Flash
Features
ChargePump^™
• V_IN 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 I_Q (50μA) for Low-Current Mode
— Drives Six Channels of LEDs
• Flash Charge Pump:
— Regulated V_{OUT_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
• Built-In Auto-Disable for Open Circuit
• Automatic Soft Start
• I_Q <1μA in Shutdown
• Available in QFN44-24 Package
Applications
• Color (RGB) Lighting
• Programmable Current Sink
• White LED Backlighting
• White Photo Flash for Digital Still Cameras
C1⁺ C1^- C2⁺ C2^- C3⁺ C3^-
VIN
VOUT
V _IN
C_IN
1μF
AAT2803
EN_FL
ENFL
D6
D5
D4
EN/SET
EN/SET
D3
D2
GND
D1
Flash
C_OUT
1μF
Backlight
D6 D5 D4 D3 D2 D1
C_OUT
1μF
2803.2006.12.1.6
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